Twin Oaks Garden blog, rainy day reading, more on hydroponics.

Y-Star Pattypan squash, one of the varieties for the Twin Oaks Garden this year.

Wren, one of the Twin Oaks Garden Managers, has started a blog about the Twin Oaks Garden. This is a great place to check what’s happening in our garden, especially if you also garden in Virginia or some other winter-hardiness zone 7 area.

The new post this week is about What’s New in Spring 2018. There are photos of people at work and also of the new varieties we’re growing this year: Southern Giant Curled Mustard, Purple Peacock broccoli/kale, Canary melon, Flavorburst yellow bell pepper, Y-Star pattypan squash, Royal Burgundy beans (not new to us, but back again), Granny Cantrell’s tomato and Persimmon tomato.

The March issue of Growing for Market is out. Nothing from me this time, but plenty of good stuff from other farmer-writers. Diane Szukovathy writes about starting a 12-member flower producer’s co-op in Seattle. They started with a part-time employee and a simple leased space, working on an indoor farmer’s market model where each farm conducted its own business under a shared roof. They were able to get some USDA funding, and increased their income immediately. Their shared setting was attractive to customers, and a good way to mentor newer growers.

Jesse Frost has written on Understanding Early Blight, with a lot of solid information from Meg McGrath at Cornell (home of the Vegetable MD Online site). Carolina Lees writes about Healthcare beyond hospitals: farm-hospital connections. Ellen Polishuk of Potomac Vegetable Farms offers a Farmer to farmer profile of Richard Wiswall (author of The Organic Farmer’s Business Handbook and designer of many labor-saving devices.) Morgan Houk writes about only collecting useful information when record-keeping, not piles of data you’ll never use. John Hendrickson brings us the latest news on the paper pot transplanter (still not certifiable for USDA Organic farms).

Paper pot transplanter,
Photo Small Farm Works

The Spring 2018 Heirloom Gardener magazine has an article from me about Intercropping (planting two crops side by side in the space normally reserved for just one. In early spring we often sow snap peas down the center of a spinach bed (either an overwinterred spinach bed, or a spring-planted one). The same piece of rowcover warms both (until we whisk away the rowcover to a later crop. The peas grow upwards, not competing with the spinach. When the spinach bolts, the next crop is in place with no further work.

In the summer we have sown peanuts down the center of a bed of lettuce, and transplanted okra into a bed of early cabbage. It’s all about timing and about choosing compatible crops. Okra grows tall, while cabbages stay close to the ground. peanuts grow slowly while lettuce grows quickly.

Overwintered spinach with spring-sown Sugar Ann snap peas.
Photo Kathryn Simmons

Lastly I have more on hydroponics and Organic Certification.

Last week I wrote about the November 2017 vote at the National Organic Standards Board (NOSB) on hydroponics. Since then I’ve read more information, and realized that the view I presented last time is not the whole picture. It is more complex. Audrey Alwell wrote in the Organic Broadcaster for Jan/Feb 2018, reminding us that the 8:7 vote at the NOSB is not a clear stamp of approval for “organic” hydroponics and aquaponics. The NOSB rules require a “decisive vote” (10:5) for a decision. They did not get a decisive vote to prohibit hydroponics from Organic Certification. This means the situation continues for now as it has been. That is, Organic certifiers can certify hydroponic operations of growers using only approved inputs for fertility and pest management, and if they are protecting natural resources and fostering biodiversity.

The Organic label does not cover all the important aspects of ethical and sustainable farming. Not all Organic practices are sustainable. (Think about removing and trashing plastic mulch!) Social justice and fair trade are not addressed. Some hydroponic  growers use renewable energy, some see hydroponics as more sustainable than Organic. In California, during the 6 year drought, hydroponics helped some farmers survive and produce food. Adaptability is important.

One USDA-accredited certifier, CCOF, says all producers should be pushed towards using renewable energy, in order to reduce impact on natural resources. CCOF submitted a 12-page comment.

You can see the USDA Hydroponics Package slideshow.

Continue reading

Real Organic Project, Mother of a Hubbard, Twin Oaks Garden Calendar

The Real Organic Project is taking off where the Keep The Soil in Organic Project is stopping, after several USDA decisions that disregard what organic farmers have to say (allowing hydroponics, setting aside animal welfare, and reducing the role of the National Organic Standards Board.) The hard-working campaigners for genuine organic standards are  disappointed, but are not giving up. Dave Chapman, a leading light of Keep the Soil in Organic, has this report:

“The Past

It has not been a good year for the National Organic Program. Since the November NOSB (National Organic Standards Board) meeting in Jacksonville failed to prohibit HYDRO, the organic community has gone through a period of questioning and searching. We are wrestling with the basic question, “Can we trust the USDA to protect organic integrity?”

Following a series of devastating articles about the NOP (National Organic Program) in the Washington Post last year, all the news from the USDA has been bad. In September, the USDA exonerated the enormous Aurora Dairy CAFO (Confinement Animal Feeding Operation) of any wrongdoing at their Colorado “farm.” This dairy operation was described in detail in one WaPo article, along with compelling test results to prove the cattle weren’t on pasture. The government approval set the stage for Aurora to build several new CAFOs that will dwarf the current 15,000-cow operation.

Then the USDA abandoned the animal welfare reforms (called OLPP) which had finally been approved under Obama. This rejection by the USDA was the result of intense lobbying from such groups as the Coalition For Sustainable Organics (in their Senate testimony), American Farm Bureau, and the National Pork Producers Council. They were championed by the ranking members of the Senate Agriculture Committee, protecting enormous “organic” egg CAFOs in their home states. The USDA thus cleared the way for CAFOs to continue receiving “organic” certification.

Then in January, the USDA announced that “Certification of hydroponic, aquaponic and aeroponic operations is allowed under the USDA organic regulations, and has been since the National Organic Program began.” This was an interesting rewriting of history, but who cares about the facts?

Finally, the USDA recently told the National Organic Standards Board (NOSB) that, going forward, they will be severely limited in the scope of their work. They will not address big questions about organic integrity. They will not set their own agenda. They will limit their focus to defining what substances will be permitted in organic certification.

These outcomes (allowing hydro, setting aside animal welfare, and reducing the role of the NOSB) are exactly what Theo Crisantes of the Coalition For Sustainable Organics called for when he testified before the Senate Ag Committee last year.

It would appear that the USDA is no longer even bothering to woo the organic community with sweet talk. They are bluntly speaking their truth, which is that “Certified Organic” means whatever they want it to mean, and to hell with the organic community. And apparently, to hell with OFPA as well. Organic is all about marketing, isn’t it?

For the many people who have spent years working hard to build the integrity of the NOP, this is a dismal moment. We have lost the helm, and the New Organic will not have much to do with the ideals of such pioneers as Albert Howard and Eve Balfour. It will have to do with money. Money will decide what is called “certified organic” and what isn’t.

And so, if we still care about those ideals, we must move on. The National Organic Program will continue to flourish. Many people will still turn to it to find safer food. Many good people will still work hard to make the NOP as honest and positive as possible. But the NOP will be controlled by politicians and lobbyists who have no belief in the mission of the organic farming movement.

What happens now?

This winter, a growing group of farmers and eaters have formed the Real Organic Project. The Real Organic Project will work to support real organic farming.

This will involve a number of efforts, starting with the creation of a new “Add-On” label to represent the organic farming that we have always cared about. It will use USDA certification as a base, but it will have a small number of critical additional requirements. These will differentiate it from the CAFOs, HYDROs, and import cheaters that are currently USDA certified.

This group grew out of several meetings of Vermont farmers who believed that the USDA label was no longer something that could represent us. Starting a new label is not a small task, but we can no longer find an alternative. That small group of Vermonters has grown quickly into a national group. This amazing group of organic advocates has gathered to build something new.

Standards Board // We now have a 15-member Standards Board, based on the model of the NOSB, but with much greater representation from the organic community. The 15 volunteers have a wealth of experience in both farming and regulation. There are 9 farmer members, as well as representatives from NGOs, stores, consumers, scientists, and certifiers.

The group includes 5 former NOSB members, as well as leading farmers and advocates from across the country. They will meet in March to set the first standards. They will continue to meet once a year after that to review and update. This first year there will be a pilot project with a small number of farms to test the certifying process and work out the details.

Advisory Board // There is also a distinguished Advisory Board that currently has 18 members, including 4 former NOSB members and 3 current NOSB members. It also includes many well known organic pioneers such as Eliot Coleman and Fred Kirschenmann.

Executive Board // And finally, there is an Executive Board of 5 people that includes one current NOSB member.

These boards will work together to reconnect and unite our community. Our intent is transformational. We will create a label that we can trust again.

We can only succeed with your support. Go to to become a member. Make a donation to help make this new label into a reality. We are only supported by our sweat and your generosity. We can reclaim the meaning of the organic label together.


Mother of a Hubbard Cathy Rehmeyer ran a wonderful blog in 2012-2015, with great tips for serious food gardening. Her work Garden Under Cover: Winter Vegetable Production in Low Tunnels is on SlideShare. So far, I don’t think it has appeared as a book. (But it should!)

A flat of newly emerged lettuce seedlings
Photo Kathryn Simmons

And here’s a seasonal reminder about the Twin Oaks Garden Calendarour month-by-month task list for our 3.5 acre, central Virginia winter-hardiness zone 7a vegetable garden that feeds 100 people year round. At the link you will find a photo from each month, which you can click to get to the list for that month. A new season, a new opportunity, using lessons learned last year, along with fresh ideas, inspiration and plain old hard work!

Rhubarb is on its way! So far just clusters of leaves near the ground, but the promise is there! And next week I’ll tell you more about my upcoming book, The Year Round Hoophouse.

Rhubarb in early spring, not yet ready to harvest.
Photo Kathryn Simmons

Asian Green for February: Tatsoi

A large tatsoi plant in our hoophouse in December. Photo Kathleen Slattery

Tatsoi is a very cold-hardy green (down to 10°F, –12°C), one of the ones we grow in our hoophouse to feed us after the winter solstice, when the crops have started to be fewer in number and each is less abundant in production rate.  We have also grown this one outdoors in the fall for early winter eating, but no longer do this as the rate of growth inside the hoophouse is much better. In the fall tatsoi will not bolt, but in late winter/early spring it will.

I have been writing about a particular Asian green once a month since last May. To find the other articles, click the category “Asian Greens”.

Like Asian greens in general, tatsoi is a great crop for filling out winter CSA bags or market booths, and ultimately, dinner tables. Because the Asian greens are so varied in color, texture, shape and spiciness, you can add a lot of diversity to your crops by growing a selection that is easy to grow and can all be treated the same way. They are as easy to grow as kale. They germinate at a wide range of temperatures and make fast growth (much faster than lettuce in cold weather!)

Botanically, tatsoi is Brassica rapa var. narinosa, cousin of other turnip family greens such as Chinese cabbage, Tokyo Bekana, pak choy, mizuna and komatsuna. It is a more distant cousin of the Brassica oleracea greens such as Vates kale, Chinese kale and kai-lan, and of crops in the Chinese Mustard family, Brassica juncea (the frilly mustards like Ruby Streaks and Golden Frills).

Tatsoi is a relatively small plant with shiny, dark green spoon-shaped leaves and green-white stems. If given plenty of space it grows as a flat rosette, but if crowded it takes on a flowerpot shape. For sale, the whole plants are cut and the leaves banded together, so crowding them does not at all make them less marketable. It has a pleasant mild flavor.

Young tatsoi plants in our hoophouse.
Photo Bridget Aleshire

Growing Tatsoi

We direct sow and then thin into salad mixes, leaving some to mature at 10″ (25 cm) across for cooking greens.  You can also transplant at 3-4 weeks of age in the fall, at 6″ (15 cm) apart. Although we transplant most of our brassicas, to allow the beds more time without this crop family (which we grow lots of), we direct sow this one, which will have many plants in a small space.

Tatsoi has similar care requirements to other brassicas. Very fertile soils grow the best Asian greens, so turn in leguminous cover crops or compost to provide adequate nutrition. Asian greens are shallow rooted – Pay extra attention to providing enough water to prevent bitter flavors and excess pungency. Expect to provide 1” (2.5 cm) of water per week in cooler weather, 2” (5 cm) during very hot weather.

Do close monitoring for pests, which can build up large populations during late summer. We do nothing special for our tatsoi, but if you have a lot of brassica flea beetles or uncontrolled caterpillars, cover the sowings or new transplants with insect netting such as ProtekNet.

If you are growing tatsoi outdoors in late fall, you could use rowcover to keep your plants alive longer into the winter.

For our hoophouse, we make a first sowing of tatsoi in the very first bed we prepare for winter crops, on 9/6. We make a second sowing in mid-November. The first sowing will feed us for two months, November and December.  The second sowing will feed us for a much shorter period of time: the second half of February, first week of March. It would bolt if we tried to keep it any longer.

It is entirely possible to make sowings between 9/6 and 11/15, and get harvests that last longer than our 11/15 sowing. The only reason we don’t is that we have so many other crops we love.

Kitazawa Seeds have a Red Violet tatsoi/pak choy hybrid, with an upright habit. They classify tatsoi as a type of pak choy/bok choy/pak choi, so if you are perusing their interesting site, this is how to find tatsoi.

Tatsoi ready for harvesting of whole plants.
Photo Pam Dawling

Harvesting Tatsoi

Tatsoi takes 21 days to be big enough for baby salads; 45 days for cooking size.

To harvest, initially we thin the rows to 1″ (2.5 cm), using baby plants in salad mix. Our first sowing provides thinnings from 10/8, one month after sowing. Next we thin to 3″ (7.5 cm), using these also for salad. Our next thinning, to 6″ (15 cm) gives us small plants for cooking. After this, we harvest individual leaves for salad or cooking. The second sowing provides thinnings 12/27-1/21 approximately.

Once we get close to the time the plants would bolt, we pull up whole plants and use them for cooking. We pull the most crowded plants first, giving the others time to grow bigger – they can grow as big as 12″ (30 cm) across. Overcrowding can lead to early bolting.

Overview of Winter Hoophouse Greens

In the big scheme of things, we harvest Tokyo Bekana and Maruba Santoh for heads in December, along with our first tatsoi; our first Yukina Savoy, our Chinese cabbage and Pak Choy in January, our second tatsoi and Yukina Savoy in February and early March.

Non-heading leafy greens such as Senposai, spinach and chard feed us all winter until mid-March when we need the hoophouse space for spring crops. (Read more about Yukina Savoy here in March.)

After Tatsoi

We clear our first tatsoi by 1/14, and use the space to sow our fifth spinach on 1/15. This planting of spinach is to be used as bare root transplants outdoors in March. Our second tatsoi is cleared 3/12 to prepare the space for early summer crops like tomatoes, peppers, beans, squash and cucumbers.

Beauty in a tatsoi plant.
Photo Wren Vile

Winter-Kill Temperatures of Cold-Hardy Vegetables 2018

Here’s the long version of one of the slideshows I presented on January 13 at the Future Harvest CASA conference. Since I got home, I updated my Winter-Kill Temperatures list, which appears in the slideshow. Compared to my list for 2016, there are a few differences, nothing major. We had some extremely cold weather, as I reported last week with some sorry pictures of lettuces. Now I have some photos of the outdoor crops too. The Vates kale had mixed survival, the rowcovered Reflect and Avon spinach are damaged but OK, the Tadorna leeks are battered but hanging in there (so are we!).

Vates kale which survived temperatures of -8F and -9F outdoors, uncovered.
Photo Pam Dawling

Vates kale with a freeze-killed center January 19 2018.
Photo Pam Dawling

For several years I have been keeping records of how well our crops do in the colder season. I note each increasingly cold minimum temperature and when the various crops die of cold, to fine tune our planting for next year. We had some extremely cold temperatures of -8°F and -9°F (-22°C and -23°C) in early January 2018. We are in zone 7a, with an average annual minimum temperature of 0-5°F (-18°C to -15°C).

Unless otherwise stated, these are killing temperatures of crops outdoors without any rowcover. All greens do a lot better with protection against cold drying winds. Note that repeated cold temperatures can kill crops that can survive a single dip to a low temperature, and that cold winds, or cold wet weather can destroy plants quicker than simple cold. Your own experience with your soils, micro-climates and rain levels may lead you to use different temperatures in your crop planning.

Hoophouse Notes

Our double-skin hoophouse keeps night time temperatures about 8F (4.5C) degrees warmer than outdoors, sometimes 10F (5.5C) warmer. Plus, plants tolerate lower temperatures inside a hoophouse. The soil stays warmer and the plants recover in the warmer daytime conditions (it seems to be the night+day average temperature that counts).

In the hoophouse (8F warmer than outside) plants without extra rowcover can survive 14F colder than they could survive outside; 21F colder than outside with rowcover (1.25oz Typar/Xavan).

For example, salad greens in a hoophouse can survive nights with outdoor lows of 14°F (-10°C) without inner rowcover. Lettuce, mizuna, turnips, Russian kales, Senposai, Tyee spinach, tatsoi, Yukina Savoy survived a hoophouse temperature of 10.4°F (-12°C) without rowcover, -2.2°F (-19°C) with. Bright Lights chard got frozen leaf stems.

Lettuce hardy enough for a solar heated winter hoophouse in zone 7a (hardiest are in bold): Buckley, Ezrilla, Green Forest, Green Star, Hampton, Hyper Red Rumpled Wave, Marvel of Four Seasons, Merlot, New Red Fire, North Pole bibb, Outredgeous, Pirat, Red Cross bibb, Red Sails, Red Salad Bowl, Red Tinged Winter, Revolution, Rouge d’Hiver, Salad Bowl, Sylvesta bibb, Tango, Winter Marvel, Winter Wonderland.

35°F (2°C):  Basil.

32°F (0°C):  Bush beans, cauliflower curds, corn, cowpeas, cucumbers, eggplant, limas, melons, okra, some Pak Choy, peanuts, peppers, potato vines, squash vines, sweet potato vines, tomatoes.

27°F (-3°C): Many cabbage varieties, Sugarloaf chicory (takes only light frosts).

25°F (-4°C): Some cabbage, chervil, chicory roots for chicons, and hearts, Chinese Napa cabbage (Blues), dill (Fernleaf), endive (Escarole more frost-hardy than Frisée), some fava beans (Windsor), annual fennel, some mustards (Red Giant, Southern Curled) and Asian greens (Maruba Santoh, Mizuna, most Pak Choy, Tokyo Bekana), onion scallions (some are much more hardy), radicchio.

Spinach under rowcover, with our hoophouse in the background – crop protection pays!
Photo Pam Dawling

22°F (-6°C): Some arugula (some varieties are hardier), Bright Lights chard, large leaves of lettuce (protected hearts and small plants will survive colder temperatures), rhubarb stems and leaves.

20°F (-7°C): Some beets (Bulls Blood, Chioggia,), broccoli heads (maybe OK to 15F), Brussels sprouts, some cabbages (the insides may still be good even if the outer leaves are damaged), celeriac, celtuce (stem lettuce), some head lettuce, some mustards/Asian greens (Tendergreen, Tyfon Holland greens), flat leaf parsley, radishes (Cherry Belle), most turnips (Noir d’Hiver is the most cold-tolerant variety).

Large oat plants will get serious cold damage. Oats seedlings die at 17°F (-8°C)

Canadian (spring) field peas are hardy to 10-20°F (-12 to -7°C).

15°F (-9.5°C): Some beets (Albina Verduna, Lutz Winterkeeper), beet leaves, some broccoli, some cabbage (Kaitlin, Tribute), covered celery (Ventura), red chard, cilantro, endive, fava beans (Aquadulce Claudia), Red Russian and White Russian kales, kohlrabi, some lettuce, especially medium-sized plants with 4-10 leaves (Marvel of Four Seasons, Olga, Rouge d’hiver, Tango, Winter Density), curly leaf parsley, rutabagas (American Purple Top Yellow, Laurentian) if not covered, broad leaf sorrel, most covered turnips, winter cress.

12°F (-11°C): Some beets (Cylindra,), some broccoli, Brussels sprouts, some cabbage (January King, Savoy types), carrots (Danvers, Oxheart), most collards, some fava beans (mostly cover crop varieties), garlic tops if fairly large, most fall or summer varieties of leeks (Lincoln, King Richard), large tops of potato onions, covered rutabagas, Senposai leaves (the core of the plant may survive 10°F/-12°C), some turnips (Purple Top).

10°F (-12°C): Covered beets, Purple Sprouting broccoli for spring harvest, a few cabbages (Deadon), chard (green chard is hardier than multi-colored types), some collards (Morris Heading can survive at least one night at 10F), Belle Isle upland cress, some endive (Perfect, President), young Bronze fennel, probably Komatsuna, some leeks (American Flag, Jaune du Poiteau), some covered lettuce (Pirat, Red Salad Bowl, Salad Bowl, Sylvesta, Winter Marvel), covered winter radish (Daikon, China Rose, Shunkyo Semi-Long survive 10°F/-12°C), large leaves of savoyed spinach (more hardy than flat leafed varieties), Tatsoi, Yukina Savoy.

Oats cover crop of a medium size die around 10°F (-12°C). Large oat plants will die completely at 6°F (-17°C) or even milder than that.

5°F (-15°C): Garlic tops even if small, some kale (Winterbor, Westland Winter), some leeks (Bulgarian Giant, Laura), some bulb onions, potato onions and other multiplier onions, smaller leaves of savoyed spinach and broad leaf sorrel. Many of the Even’Star Ice Bred greens varieties are hardy down to 6°F (-14°C), a few unprotected lettuces if small (Winter Marvel, Tango, North Pole, Green Forest).

Tadorna leeks, struggling but not dead, after -9F.
Photo Pam Dawling

0°F (-18°C): Chives, some collards (Blue Max, Winner), corn salad (mache), garlic, horseradish, Jerusalem artichokes, a few leeks (Alaska, Durabel, Tadorna); some bulb onions, yellow potato onions, some onion scallions, (Evergreen Winter Hardy White, White Lisbon), parsnips (probably even colder), salad burnet, salsify (?), some spinach (Bloomsdale Savoy, Olympia, Tyee). Walla Walla onions sown in late summer are said to be hardy down to -10°F (-23°C), but I don’t trust below 0°F (-18°C)

Crimson clover is hardy down to 0°F (-18°C) or slightly colder

-5°F (-19°C): Leaves of overwintering varieties of cauliflower die, Vates kale survives although some leaves may be too damaged to use.

Reflect spinach in the open got damaged but not killed at -9F.
Photo Pam Dawling

-10°F (-23°C) Austrian Winter Field Peas and Crimson clover (used as cover crops).

-15°F (-26°C) Hairy vetch cover crop – some say down to -30°F (-34°C)

-20°F (-29°C) Dutch White clover cover crops – or even -30°F (-34°C)

-30°F to -40°F (-34°C to -40°C): Narrow leaf sorrel, Claytonia and some cabbage are said to be hardy in zone 3

-40°F (-40°C) Winter wheat and winter rye (cover crops).

A cover crop of winter wheat untroubled by -9F.
Photo Pam Dawling

Cold-tolerant lettuce and the rest

Good survival of Green Forest and Revolution lettuce (sown September 24) in our hoophouse after the Big Freeze, on January 10.
Photo Pam Dawling

We keep a list of lettuce varieties for each season. We had extremely cold weather at New Year, -3F on Jan 2 and Jan 3, followed by -8F on Jan 6 and -9F on Jan 7. In past years we did not often need to add inner rowcover over our crops in the hoophouse at night, but in recent years, this has become more common. Our guideline is that if we expect the night-time low to be 8F or lower, we use rowcover. This winter, even with rowcover, we lost some lettuce and pak choy. Here are some before (December 20) and after (January 10) photos and notes.

Merlot lettuce on December 20.
Photo Pam Dawling

Merlot lettuce from our September 15 sowing on January 10.
Photo Pam Dawling

Merlot is one of our favorite reds and previously we regarded it as one of our more hardy varieties. Other ones from last year’s list of hardy varieties include Green Forest, Hyper Red Rumple Wave, Tango, Winter Marvel and Red Tinged Winter.  Hyper Red Wave (as we call it for short) didn’t do so well either.

Hyper Red Rumple Wave from our September 15 sowing, on January 10.
Photo Pam Dawling

Nor did Outredgeous from the earlier sowing, although the later sowing did better – the plants were smaller. Often smaller (younger, not stunted!) plants can survive colder temperatures.

Outredgeous lettuce from our September 15 sowing, on January 10.
Photo Pam Dawling

Outredgeous lettuce from our September 24 sowing still alive but with some damage on January 10.
Photo Pam Dawling

The real stars of red lettuce for cold-hardiness this winter have been Revolution from Fedco Seeds and Buckley from High Mowing.

Revolution lettuce in the foreground, Buckley in the background, on January 10.
Photo Pam Dawling

Another big star is Red Tinged Winter from Fedco Seeds. That’s the one I harvested leaves from on January 10.

Red Tinged Winter lettuce from our Septemebr 24 sowing in our hoophouse on January 10.
Photo Pam Dawling

Tango lettuce from our September 24 sowing on January 10.
Photo Pam Dawling

And, for green lettuce, Tango, also from Fedco, came through, as always.







Green Forest lettuce from our September 15 sowing on January 10.
Photo Pam Dawling

Our Green Forest romaine had mixed results. Once again the bigger, older sowing survived less well.

The same Green Forest lettuce on December 20. Photo Pam Dawling

Hampton lettuce from our September 24 sowing. One plant has collapsed with sclerotinia lettuce drop.
Photo Pam Dawling

Other green lettuces include Hampton and Ezrilla, two more of High Mowing’s Eazyleaf lettuce varieties. Not as hardy as their red Buckley, but not as wimpy as some. The older sowing of Hampton died, but the younger (seen here) mostly survived. We did not have any Ezrilla in our later planting. Now I wish we had, as I like this lettuce.

Ezrilla lettuce from our September 15 sowing on January 10. The damage was quite variable.
Photo Pam Dawling





Remember that these lettuces have been through very cold temperatures. That any survived is remarkable. We will learn from this and adjust our variety list before next winter!

Asian Greens for January: Chinese Cabbage

Sorry for the delay this week – technical problems.

Young Chinese cabbage transplants in our hoophouse in October. Photo by Bridget Aleshire

If you have Chinese cabbage in your hoophouse, January is the month to harvest it in zone 7. We do not harvest leaves from this crop, but wait for it to form full-size heads and then harvest those mature plants. We sometimes start harvesting as early as December 4, if the plants have reached full size and we “need” to harvest them. Otherwise we wait till December 15. If we have planted enough we can harvest until January 23, or sometimes as late as February 9.

Other Asian greens we are also harvesting at this time of year include pak choy, mizuna and the frilly mustards, tatsoi, Senposai, Tokyo Bekana, Maruba Santoh and Yukina savoy.

Chinese cabbage has very tender, light green savoyed leaves and is excellent for stir-fries, or pickling (sauerkraut or kimchee).

Chinese cabbage (both the Napa kind and the Michihli or Michihili kind) are Wong Bok types (Brassica rapa var. pekinensis) along with the “celery cabbages” – the non-heading Tokyo Bekana and Maruba Santoh.

We like Blues, an open-pollinated “barrel-shaped” Napa cabbage, shown in the photo above. Kasumi has the best bolt tolerance and is larger: 5 lb (2.3 kg) compared to 4 lb (1.8 kg); Orange Queen is a colorful but slower-growing variety (80 days in spring).

Napa and Michihili Chinese cabbages in October.
Photo Wren Vile

The Michihili types are taller and narrower, can be transplanted closer (8″) and might make more sense in terms of space use, although Napa cabbages do store better under refrigeration than michihli types. Jade Pagoda and the O-P Michihli both take 72 days from sowing to harvest in spring – considerably slower than Napa types. Michihili are more stress tolerant and resistant to bolting and black speck than Napa cabbage.

Blues takes 52 days from sowing to harvest in spring, but of course, takes longer in fall and winter. We sow September 15 in an outdoor nursery seedbed, and transplant into our hoophouse at 2-3 weeks old (October 2). It is very fast-growing in those temperatures and conditions. If we start harvesting December 15, it’s 3 calendar months from sowing, 91 days. The minimum germination soil temperature for Chinese cabbage is 50F (10C), and the ideal soil temperatures are 68F (20C) to 86F (30C). Under the ideal conditions the seedlings will emerge in 4 days. The maximum soil temperature to get any germination is 95F (35C).

We plant 52  plants for 100 people, with 4 staggered rows in the 4ft bed, 10.5″ apart (every 7th tine on Johnny’s row marker rake) and plants 10″ apart. With a harvest period of 5-8 weeks, 6-10 heads per week is about right for us.

We have not had many disease or pest problems with our hoophouse Chines cabbage. We do pay attention to using insect netting over the outdoor seedbed in the fall, but once we transplant indoors, our pest troubles are usually over. Vegetable weevil larvae have caused trouble in January. They come out of the soil at night and make holes in the leaves. They tend to prefer pak choy and turnips. We have used Spinosad against them with some success.

Chinese cabbage.
Photo Ethan Hirsh

Tipburn (brown leaf margins, including internal leaves) is caused by quick drying of the soil, when the weather makes a sudden switch to bright and sunny from overcast. Be ready to irrigate when the weather suddenly brightens.

The winter-kill temperature of Chinese cabbage outdoors without protection is 25F (-4C). Our hoophouse crop has taken outdoor temps of 8F without inner rowcovers, and -8F with added thick rowcover. It is more cold-hardy than most varieties of pak choy, and less cold-hardy than Komatsuna, Senposai, tatsoi, Yukina savoy. Mizuna, Maruba Santoh and Tokyo Bekana have a similar level of cold-tolerance.

Once past the winter solstice, the order of bolting of Asian greens is something like: Tokyo Bekana and Maruba Santoh, pak choy, Chinese cabbage, tatsoi, Komatsuna, Senposai, mizuna, Yukina Savoy, leaf radish, frilly mustards.

When it’s time to harvest, we lever and pull the plant out of the soil, then cut off the root. This helps with the next task of replanting the space. It is much easier than cutting the plants at the base and then digging up the root.

After the Chinese cabbage are all cleared, we might follow with kale or collards on January 24 to transplant outdoors as bare root transplants in March. If we have no plans for a follow-on crop that early in the year, we fill gaps in the Chinese cabbage plot until January 25, using “filler” Asian greens we sowed in October. After that date we fill all gaps with spinach transplants until February 20, and from then on we only fill gaps on the edges of beds, leaving the bed centers free for tomatoes, etc in mid-March.

Close-up of Chinese cabbage in our hoophouse in late November. Photo Pam Dawling


  • Grow Your Own Chinese Vegetables, Geri Harrington, 1984, Garden Way Publishing. Includes the names for these crops in different cultures.
  • Growing Unusual Vegetables, Simon Hickmott, 2006, Eco-Logic books, UK.
  • Oriental Vegetables: The Complete Guide for the Garden and Kitchen, Joy Larkham, revised edition 2008, Kodansha, USA
  • The Chinese Kitchen Garden: Growing Techniques and Family Recipes from a Classic Cuisine, Wendy Kiang-Spray

Garden Planning, Winter Harvests and Speaking Events

Garden Planning Field Manual
Photo VABF

‘Tis the season – after the relaxation of the holidays – time for garden planning. Inventory your seeds left from last year, peruse the catalogs and prepare your seed orders. The earlier you get them in, the more likely you are to get the varieties you want, before anything is sold out.

I notice that readers of my blog have been looking up the Twin Oaks Garden Calendar,  also known as The Complete Twin Oaks Garden Task List Month-by-Month. You can search the category Garden Task List for the Month, or you can click on the linked name of the month you want. At the end you can click on “Bookmark the Permalink” if you might want to refer to this in future. Remember, we’re in central Virginia, winter-hardiness zone 7a. Adjust for your own climate.

Meanwhile, despite the turn to cold weather, we are not huddled indoors all the time. Each day, one or two of us sally forth to harvest enough vegetables to feed the hundred people here at Twin Oaks Community. Outdoors, in the raised bed area, we have winter leeks, Vates kale, spinach and senposai. We could have had collards but we lost the seeds during the sowing period, so we have lots of senposai instead. Senposai leaves (the core of the plant may survive 10F), are hardy down to about 12F. I noticed some got a bit droopy when we had a night at 15F. Collards  are hardier – Morris Heading (the variety we grow) can survive at least one night at 10F.

Hoophouse December View
Photo Kathleen Slattery

In the hoophouse, we have many crops to choose from: lettuce, radishes, spinach, tatsoi, Yukina Savoy, Tokyo Bekana, turnips and turnip greens, scallions, mizuna, chard, Bull’s Blood beet greens.

Hoophouse scallions ready to harvest.
Photo Pam Dawling

Pak Choy and Chinese cabbage heads are filling out, ready for harvest in January.

Tokyo Bekana, a non-heading Asian green,  has large tender leaves, which we are adding to salad mixes. It can be used as a cooking green, but only needs very light cooking. It will bolt soon, so we are harvesting that vigorously, not trying to save it for later.

The kale and senposai in the hoophouse are being saved for when their outdoor counterparts are inaccessible due to bad weather. The spinach is added to salad mixes, or harvested for cooking when outdoors is too unpleasant, or growth slows down too much.

Hoophouse winter lettuce: Green Forest and Red Salad Bowl, two of our fifteen varieties.
Photo Wren Vile

Another kind of planning I’m doing right now is scheduling my speaking events for the coming year and practicing my presentations. Last week I updated my Events page, and this week I’m adding a new event: The September 21-22 Heritage Harvest Festival.

I might pick up a couple of events in late April and early June, but that’s just speculation at this point.

Right now I need to practice for the CASA Future Harvest Conference January 11-13. Cold-hardy Winter Vegetables and a 10-minute “Lightning Session” on using graphs to plan succession plantings for continuous harvest. Click the link or my Events page for more on this.

Year Round Vegetable Production, speaking events

Here’s my newest slide show, Year Round Vegetable Production, which I presented at the Field School in Johnstown, TN on December 7.  To view full screen, click the diagonal arrows at the bottom right, and to move to the next slide, click the triangle arrow pointing right.

The Field School is a Beginning Farmer program, under the Appalachian RC&D Council. The Field School organizes a monthly series of workshops (November 2017 through August 2018) that provides an overview of small-scale farming in East Tennessee’s mountains and valleys, taught by 20+ farmers and agricultural professionals. It is arranged by the Appalachian RC&D Council, Green Earth Connection, and many area partners with major support from USDA.

As well as my double presentation on Thursday evening, I attended a Q and A brunch on Friday morning and got the chance to meet the new (ish) farmers individually. It was a pleasure to meet such enthusiastic dedicated growers.

My other presentation on Thursday 12/7 was Crop Planning, which you can view by clicking the link.

The school session 2017-18 is already full even though they have expanded to have two tracks (Produce or Small Livestock) in this their third year. Go to their website if you are local and want to be on their waiting list if spots open up. They also sell tickets to the public for some of their workshops.

Beginning farmer training is available in most states, loosely under the USDA, but without a central organization. Do a web search for your state and “beginning farmer training” if you are looking for something like this. Or check out this list on

I have been firming up several speaking events in the new year. Here some info on some of those (click the Events tab  or the individual event links for for more details):

The Chesapeake Alliance for Sustainable Agriculture Future Harvest Conference January 11-13, 2018 at College Park, MD.

Ira Wallace (Southern Exposure Seed Exchange), Gabe Brown, Michael Twitty and Craig Beyrouty are giving the meal time addresses.

On Saturday January 13 11.30am -12.30pm I’m presenting

Cold-Hardy Winter Vegetables Why farm in winter? Information includes tables of cold-hardiness; details of four ranges of cold-hardy crops; overwintering crops for spring harvests; scheduling; weather prediction and protection; hoophouse growing; and vegetable storage.

I am also participating with other speakers in a new format Lightning Session Round, 2.15-3.30pm on Saturday, where we each get 10 minutes to tell the audience the top 5 things we want them to know about a certain topic. I’m speaking on Six Steps to Using Graphs to Plan Succession Crops for Continuous Harvests

I will be signing books at the Southern Exposure Seed Exchange booth at points during the conference.

February 7-10, 2018 Pennsylvania Association for Sustainable Agriculture, Farming for the Future Conference, State College, PA  I’ll be presenting three workshops:

Storage Vegetables for Off-Season Sales Friday 12.50 – 2.10 pm

Grow crops you can sell during the winter, while allowing yourself some down-time and reprieve from outdoor work. Choose suitable crops, schedules and storage conditions. Understand your weather and basic crop protection. This workshop will provide tables of cold-hardiness and details of four ranges of cold-hardy crops (warm and cool weather crops to harvest and store before very cold weather; crops to keep alive in the ground further into winter, then store; hardy crops to store in the ground and harvest during the winter, and overwinter crops for early spring harvests before the main season). It includes tables of storage conditions needed for different vegetables and suggestions of suitable storage methods, with and without electricity.

Cover Crops for Vegetable Growers Saturday 8.30 – 9.50 am

Using cover crops to feed and improve the soil, smother weeds, and prevent soil erosion. Selecting cover crops to make use of opportunities year round: early spring, summer, fall and going into winter. Fitting cover crops into the schedule of vegetable production while maintaining a healthy crop rotation.

Fall and Winter Hoophouses Saturday Feb 10 12.50-2.10pm

How to grow varied and plentiful winter greens for cooking and salads; turnips, radishes and scallions. How to get continuous harvests and maximize use of this valuable space, including transplanting indoors from outdoors in the fall. The workshop includes tips to help minimize unhealthy levels of nitrates in cold weather with short days. Late winter uses can include growing bare-root transplants for planting outdoors in spring.

There will be handouts for each workshop and book signing

March 9-11 2018, Organic Growers School Spring Conference at UNC-Asheville, Asheville, NC. I’ll be presenting three workshops:

For the Gardener track: Growing Sweet Potatoes from Start to Finish

At this workshop you will learn how to grow your own sweet potato slips; plant them, grow healthy crops and harvest good yields, selecting suitable roots for growing next year’s slips. You will also learn how to cure and store roots for top quality and minimal losses. This workshop will be useful to beginners and experienced growers alike.

For the New Farmer Track: Cover Crops for Vegetable Growers

Using cover crops to feed and improve the soil, smother weeds, and prevent soil erosion. Selecting cover crops to make use of opportunities year round: early spring, summer, fall and going into winter. Fitting cover crops into the schedule of vegetable production while maintaining a healthy crop rotation.

Sustainable Farming Practices 

An introduction to year round vegetable production; crop planning and record-keeping; feeding the soil using crop rotations, cover crops, compost making and organic mulches; production tips on direct sowing and transplanting, crop spacing, succession crop scheduling to ensure continuous harvests, efficient production strategies, season extension, dealing with pests, diseases and weeds; determining crop maturity and harvest methods.

April 12, 2018, 9am to noon,

Louisa Master Gardener Group Tour of Twin Oaks Gardens

Asian Greens for December: Pak Choy

Pak Choy in the hoophouse in December.
Photo Ethan Hirsh

December and the first three weeks of January are the season we harvest mature pak choy heads in our hoophouse. Pak choy, also known as bok choi, pac choy, and similar names, is a large 12″-15″ (30–38 cm) tall heading green, usually cut as a full head. If you prefer, you can harvest a leaf or two from each plant each time you want to eat some. It is hardy at least down to 32F (0C) outdoors. Some varieties are hardy down to 25F (-4C).

Botanically, pak choy is a Brassica rapa var. chinensis. If you plan to grow seed of more than one Asian green, carefully choose ones that won’t cross. Be aware of the possibility of brassica crops being wrongly classified.

Pak Choy in the hoophouse in early November.
Photo Pam Dawling

Pak Choy generally has thick rounded white stems, dark glossy leaves and a mild flavor. There are varieties with green stems, some with red-purple leaves such as Red Choi from Kitazawa, and some miniature varieties, such as Mei Qing Choi from Kitazawa, but we grow the full-sized white and green kinds, such as Joi Choi from Johnny’s and Prize Choy from Fedco. For the most choice, go to Kitazawa Seeds, as they stock 23 varieties (although 4 are tatois).

Like all Asian greens, pak choy is nutritious as well as tasty. It’s high in carotenoids, vitamins A and C, calcium, iron, magnesium and fiber. It contains antioxidants which fight against cancer and protect eyes from macular degeneration.

Brassica seedbed protected from insects with ProtekNet and hoops.
Photo Bridget Alsehsire

We sow for this planting in an outdoor nursery seedbed on September 15, and cover the outdoor seedbeds with insect netting. The ideal germination temperature range for Pak Choy is 45-70F, it’s very easy-going. Ideal  temperatures for growth are 60-70F. Hoophouses are perfect. The plants grow fast and we only get a few weeds to deal with.Asian greens have similar care requirements to other brassicas, and very fertile soils grow the best Asian greens.

We transplant as bare root transplants into the hoophouse just 3 weeks after sowing, around Oct 3. We plant 10″ apart, with 4 rows in a 4ft wide bed. We reckon on 52 pak choy plants for 100 people. Because the harvest period is short, it is not wise to grow too many.

Young Pak Choy transplants.
Photo Bridget Aleshire

Pak choy is shallow rooted, so pay extra attention to providing enough water during hot weather , 1” (2.5 cm) of water per week; 2” (5 cm) during very hot weather. This will prevent bitter flavors and excess pungency.

Do closely monitor for pests, which can cause havoc. We have had trouble in the hoophouse from the vegetable weevil larva. Click the link for information and great photos from Debbie Roos at Growing Small Farms. Other possible pests include flea beetles, aphids, harlequin bugs, cabbage caterpillars, grasshoppers and slugs.

Only about 8 weeks after transplanting, pak choy is ready to harvest. Because we want to keep all our hoophouse space in full use, we pull the plant out, then cut off the root. This is easier than cutting the head off at ground level, then trying to pry out the root.

Young Pak Choy plants in early November, with some darker Yukina Savoy on the right.
Photo Wren Vile

That same day we fill the gaps with some younger transplants (sown 10/10 in the hoophouse), that we have in reserve. We call these “filler greens.” We stop filling gaps with Asian greens (and lettuces) on Jan 25, and follow the pak choy with a sowing of kale to be transplanted outdoors in early March.

There’s a good publication from Iowa State Extension on  Commercial Production of Pak Choi. As an organic grower, I don’t use the herbicides and pesticides they mention, but the publication is good on identifying pests and diseases as well as covering the basic growing needs.

See ATTRA’s Cole Crops and Other Brassicas: Organic Production for more information than I can cover here.

In areas with cool or mild springs, pak choy can be a spring green, but that doesn’t work with our short springs – they just bolt rather than size up. Growing outdoors for fall harvest and in the hoophouse for winter use works best here in central Virginia.

What Makes Potatoes Sprout?

Harvesting potatoes. Photo Lori Katz

“White” or Peruvian potatoes (sometimes called Irish potatoes) are stem tubers in the nightshade family; sweet potatoes are root tubers in the Morning Glory family. This article is about Peruvian potatoes, not sweet potatoes.

Curing potatoes

Potatoes are cured enough for storage when the skins don’t rub off. It’s best to leave the potatoes in the ground for two weeks after the tops die, whether naturally or because of mowing, if you want them to store. When the potatoes are harvested after the skins have toughened, there will be less damage during harvest. Curing allows skins to harden and some of the starches to convert to sugars. These changes help the tubers to store for months.

When potatoes first go into storage, they are still “alive” and respiring, and need fresh air frequently. They will heat up if left closed in, and could develop black centers, where the cells die from lack of oxygen.

Storing newly harvested potatoes

For the first two weeks after harvest, the root cellar or other storage space will need 6-9 hours of ventilation every two or three days. The temperature goal is 60°F–75°F (16°C–24°C), with 95% humidity. Ventilate when the temperature is 0–20F (0–11C) cooler than your goal: in the daytime if nights are too cold and days are mild; at night if nights are mild and days too warm. If it is very damp in there, ventilate more.

Two weeks after harvest, sort all the potatoes. By this time, any which are going to rot have likely started doing so. Restack, remembering to keep airspace between the crates and walls. For weeks 2–4, the temperature goal is 50°F (10°C) and fresh air is needed about once a week.

Potato crates in our root cellar.
Photo Nina Gentle

Long term potato storage

After week 4 in winter, cool to 40°F (5°C); in summer, below 50°F (10°C). Ventilation for air exchange is no longer needed, as the tubers have become dormant. The final long-term storage conditions are cool and fairly moist, 40°F–50°F (5°C–10°C), 85%–90% humidity—a  root cellar is ideal. Below 40°F (5°C) some starches convert to sugars, giving the potatoes a bad flavor and causing them to blacken if fried. Try hard to avoid having the cellar cool down, then warm up. That causes the potatoes to sprout.

Pre-sprouting seed potatoes

Potatoes have a dormant period of 4–8 weeks after harvest before they will sprout. The warmer the conditions after dormancy ends, the quicker they will sprout. If you want potatoes to sprout during the dormant period, trick them by refrigerating for 16 days, then pre-sprouting them in the light.

We routinely “chit” or pre-sprout our seed potatoes before planting. Bring the seed potatoes into a warm, well-lit room around 65°F–70°F (18°C–21°C) and set them upright in shallow boxes, rose end up, stem (belly-button) down, for 2–4 weeks in spring, 1–2 weeks in summer. For summer planting, store your seed potatoes in a cool place at 45°F–50°F (7°C–10°C) until 2 weeks before your planting date, then sprout them.

Seed potato pieces after pre-sprouting for planting.
Photo Kati Falger

The effects of ethylene

Ethylene is a naturally occurring, odorless, colorless gas produced by many fruits and vegetables, but it can also be produced by faulty heating units and combustion engines. Propane heaters should not be used, as propane combustion produces ethylene. Incomplete combustion of organic fuels can result in the production of carbon monoxide, ethylene and other byproducts. Do not use any unvented hydrocarbon fuel heaters near stored produce.

Ethylene is associated with ripening, sprouting and rotting. Some crops produce ethylene in storage—apples, cantaloupes, ripening tomatoes, already-sprouting potatoes all produce higher than average amounts. Chilling, wounding and pathogen attack can all induce ethylene formation in damaged crops.

Some crops, including most cut greens, are not sensitive to ethylene and can be stored in the same space as ethylene-producing crops. Other crops are very sensitive and will deteriorate in a high-ethylene environment. Potatoes will sprout, ripe fruits will go over the top, carrots lose their sweetness and become bitter.

Summary: Potatoes are more likely to sprout if they are more than 4–8 weeks after harvest; in the light; near fruits, vegetables, flowers or malfunctioning propane or natural gas heaters that produce ethylene; too warm, or warm after being cool.  Potato sprouts are toxic, see my earlier article.

Planting potatoes.
Photo Wren Vile