Dragonfly Swarms, Mother Earth News, and Heritage Harvest Festival

Dragonfly photo courtesy Staunton News Leader

Swarms of dragonflies are popping up  in Virginia

Leanna Smith, in the Staunton News Leader reported that meteorologists in Ohio had spotted something unexpected on the radar on September 10 — a swarm of migrating dragonflies. The radar maps are impressive! The Common Green Darner dragonflies (Anax junius) were reported swarming in Maryland (Sep 11 evening), New Jersey (Sep 12 nighttime) and Virginia (Sep 11 and Sep 12 morning).

She reported that it is common for dragonflies, especially green darner dragonflies, to migrate south in the fall to find warmer weather, but the swarming is unusual. Ohio State University Entomology Professor Norman Johnson spoke to CNN and said that weather conditions can cause the traveling insects to swarm. In 2018, the Washington Post reported that the migration of green darner is typically unremarkable because the insects rarely travel in packs. Although much is still unknown about the migration of dragonflies, we do know that they are very sensitive to temperature. “Climate warming could really disrupt the presence of this migration,” Colin Studds, an animal ecologist at the University of Maryland Baltimore County, told the Post.

It is fairly common for radar to pick up biological movement, especially around sunrise and sunset when warmer air above us can bend the radar beam toward lower elevations where the movement is occurring, according to meteorologist Chris Michaels.

On September 10, the National Weather Service of Cleveland, Ohio tweeted about the new development.

Clouds of dragonflies.
Photo NWS Cleveland @NWSCLE

Ohio State University entomologist Norman Johnson said the dragonflies are likely Green Darners, which migrate south in the fall. “The insects don’t usually travel in flocks,” he told CNN, “but local weather conditions can cause them to bunch up.” “The big swarms have been recorded a lot over the years, but they’re not regular,” Johnson said.

Details of dragonfly migration are still unclear; researchers have found the winged creatures travel an average of 8 miles per day, but can fly as far as 86 miles.

For up to the minute sightings, see the Migratory Dragonfly Partnership Search page

TOWARD THE UNKNOWN  A common green darner can migrate hundreds of kilometers each year. A new study reveals details of the insects’ annual migration for the first time. Photo Mark Chappell

Susan Milius in Science News reports that Green Darner dragonflies migrate a bit like monarch butterflies, with each annual migratory loop taking multiple generations to complete.

Ecologist Michael Hallworth and colleagues wrote the migration of the common green darner, described December 19, 2018 in Biology Letters, using data on forms of hydrogen in the insects’ wings, plus records of first arrivals spotted by citizen scientists. Citation https://doi.org/10.6084/m9.figshare.c.4320911.v2

“A first generation of insects emerges in the southern United States, Mexico and the Caribbean from about February to May and migrates north. Some of those Green Darners reach New England and the upper Midwest as early as March, says Hallworth, of the Smithsonian Migratory Bird Center headquartered in Washington, DC.

Those spring migrant darners lay eggs in ponds and other quiet waters in the north and eventually die in the region. This second generation migrates south from about July until late October, though they have never seen where they’re heading. Some of these darners fly south in the same year their parents arrived and some the next year, after overwintering as nymphs.

A third generation emerges around November and lives entirely in the south during winter. It’s their offspring that start the cycle again by swarming northward as temperatures warm in the spring. With a wingspan as wide as a hand, they devote their whole lives to flying hundreds of kilometers to repeat a journey their great-grandparents made.

Tracking devices that let researchers record animals’ movements for more than a week or two haven’t been miniaturized enough to help. The smallest still weigh about 0.3 grams, which would just about double a darner’s weight, Hallworth says. So researchers turned to chemical clues in darner tissues. Conservation biologist and study coauthor Kent McFarland succeeded at the delicate diplomacy of persuading museums to break off a pinhead-sized wing tip fragment from specimens spanning 140 years.

Researchers checked 800 museum and live-caught specimens for the proportion of a rare heavy form of hydrogen that occurs naturally. Dragonfly wings pick up their particular mix of hydrogen forms from the water where the aquatic youngsters grow up. Scientists have noticed that a form called hydrogen-2 grows rarer along a gradient from south to north in North America. Looking at a particular wing in the analysis, “I can’t give you a zip code” for a darner, Hallworth says. But he can tell the native southerners from Yankees.

An adult darner, regardless of where it was born, is “a green piece of lightning,” says McFarland, of the Vermont Center for Ecostudies in White River Junction. Darners maneuver fast enough to snap insect prey out of the air around ponds across North America. The front of an adult’s large head is “all eye,” he says, and trying to catch samples for the study was “like hitting a knuckleball.”

Although the darners’ north-south migration story is similar to that of monarch butterflies (Danaus plexippus), there are differences, says evolutionary biologist Hugh Dingle of the University of California, Davis, who has long studied Monarchs, which move northward in the spring in successive generations, instead of one generation sweeping all the way north.

Also, Dingle says, pockets of monarchs can buck the overall scheme. Research suggests that some of the monarchs in the upper Midwest do a whole round trip migration in a single generation. As researchers discover more details about green darners, he predicts, the current basic migration scheme will turn out to have its quirky exceptions, too.”

MASS MIGRATION

At least three generations make up the annual migration of common green darner dragonflies. The first generation emerges in the southern United States, Mexico and the Caribbean starting around February and flies north. There, those insects lay eggs and die, giving rise to second generation that migrates south until late October. (Some in that second generation don’t fly south until the next year, after overwintering as nymphs.) A third generation, hatched in the south, overwinters there before laying eggs that will start the entire process over again. These maps show the emergence origins of adult insects (gray is zero; red is many) captured at sampling locations (black dots).

Diagram by Matthew Dodder, M.T. Hallworth et al/Biology Letters 2018

Geek.com reports that this isn’t the first insect invasion of 2019. In June, the National Weather Service’s radar in San Diego picked up a giant crush of ladybugs about 80 miles across in each direction, over southern California. On June 27, residents of northeastern Ohio found themselves dealing with invasive mayflies, which covered cars, houses, and lampposts across Cleveland, Sandusky, and other areas.

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Mother Earth News Fair

I had a great time at the Mother Earth News Fair at Seven Springs, Pennsylvania. My first workshop, Lettuce Year Round, was on Friday lunchtime and attendees were still arriving. For those who wanted to hear all about it, but missed it, here is the slideshow:

And here is the extended version of Hoophouse Cool Season Crops. It has a lot of bonus material compared to the short workshop I gave last weekend.

Note that all the offers of pdfs of my books to download are scams and nothing to do with me! I cannot stop people posting them. It’s almost enough to stop me posting my slideshows, but I know people appreciate another chance to see the slides.

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Heritage Harvest Festival

This coming weekend, Saturday September 21, I’ll be presenting Winter Gardening: No Tech to High Tech with Ira Wallace at the Heritage Harvest Festival at Monticello in Charlottesville, VA. Ira will talk about outdoor winter gardening, and I’ll talk about hoophouse growing (which isn’t really that high tech!) It’s Saturday, Sept. 21 at 10:30am in the Heritage Tent. Here’s the LINK. The workshop is for gardeners to learn tips on growing cold-hardy vegetables (and not just kale!) out in the open and with varying degrees of protection from rowcovers, low tunnels, coldframes and hoophouses.

Read more about the Heritage Harvest Festival here

Buy tickets in advance here

Weeding rowcovered spinach in winter.
Photo Wren Vile

Potato Research, Mother Earth News Fair PA and Heritage Harvest Festival

Crates of potatoes in our root cellar.
Photo Nina Gentle

Potato Research on Harvest and Storage

Last week I mentioned that while researching potato yield figures, I found an interesting publication, The Potato Association of America, Commercial Potato Production in North America 2010. I’ve been reading that and learning more about potatoes. Here I’m going to focus on harvest and storage, because that’s the bit we’re currently challenged by. I also learned more about planting in hot weather, but that’s for another time.

Potato harvest.
Photo Nina Gentle

In England we planted in spring and harvested in October, waiting for the frost to kill the vines. In Virginia we plant in March and June, harvesting in July and October. We have grown Red Pontiac, Yukon Gold and Kennebec here, mostly. They all seem to be determinate varieties. I only just learned there are determinate (varieties with naturally self-limiting growth, generally “early” varieties) and indeterminate varieties (such as “Russet Nugget,” “Nicola,” “German Butterball” and “Elba”). The distinction is explained in Potato Bag Gardening. Growers using towers, grow bags, and cage systems want indeterminate potatoes, which continue to produce more layers of tubers on the stems as they are progressively covered with more soil. Growers wanting a fast reliable crop in the field mostly choose determinate types, which grow as a bush, then flower and die. The Wild Woolly Web does seem to have some contradictory statements about which varieties are determinate and which indeterminate, and some dedicated container growers make assertions not supported by experienced commercial growers. So Reader Beware! I trust Extension and here’s a link to their Ask an Expert page on potato types, and the University of Maryland Extension Home and Garden Info Center Potatoes.

June-planted potatoes in early September
Photo Kathryn Simmons

Whether the vines die naturally at the end of their lifespan, or they die of disease, or the frost kills them, or you kill them yourself by mowing or flaming, the potatoes will store better if you then wait 2-3 weeks before harvesting. The potato skins thicken up (becoming more resistant to scrapes and bruises) and the potatoes become higher in dry matter. Harvesting is easier if the vines are well dead. We generally bush-hog ours. Decades ago, in England, we had late blight in the middle of the season, and we cut the tops off and made a very smoky bonfire. (I wouldn’t participate in that much air pollution nowadays!) After waiting for a couple of weeks for the late blight spores to die, we dug the potatoes. The idea was to prevent spores getting on the tubers. As I remember, it all worked out OK.

If at all possible, harvest when the soil moisture is 60-80% of field capacity. Not too dry, not too wet. This reduces damage from scraping. If using a digger, don’t set it digging too deep, or too much soil will be damped on the harvested potatoes.

Tuber temperature will also impact bruise and rot susceptibility. Ideally soil temperature will be 45-65F (7-18C).  Because soil temperature lags 3-4 hours behind air temperature rise each day, in cold weather, try to harvest around 6 pm or a bit later. In hot weather, harvest in the morning.

When freshly harvested, potatoes are tender, breathing things. Avoid bruising, which is damage that does not break the skin, by not dropping potatoes more than 6” (15 cm), or throwing them towards a container. Don’t bang them to knock off extra soil.

When harvesting in summer, we stack the crates of potatoes under a big tree overnight to lose some of the field heat before moving them to the root cellar early next morning. Potatoes you take from storage can be no better than the quality of the potatoes you put into storage!

The first part of the storage period is the curing. The potatoes are still actively respiring, so they need a good oxygen supply. Failure to ventilate the cellar enough can lead to Black-heart, where the inner tissue of the potatoes dies and turns black. During the curing period, the skins further toughen up, and cut surfaces and superficial wounds heal over, enabling long term storage. The temperature should be as close to 50-58F (10-14.4C) as you can get. The lower end of the range is best for fresh eating (as opposed to junk food manufacture). Hotter temperatures will promote more rot, and age the potatoes faster, leading to early sprouting. Relative humidity should be 90%, but not 100%! If there is too much condensation, use a fan and open the cellar doors, when temperatures are closest to the goal. Curing takes 10-14 days.

Sorting potatoes .
Photo Wren Vile

We find that a single thorough sorting after 14 days can remove almost all of the storage problems that are going to happen. Not sorting at this point lets rots spread.

After the curing period, the potatoes become more dormant and do not respire so actively. They don’t need as many air changes as during curing, but if the cellar is too warm, you will need to aerate more. The temperature during the storage period should be 40-50F (4.4-10C), and closer to the lower end of the range is best. Constant temperatures or a steady decline is the goal, not dramatic fluctuations. Humidity should still be 90-95%, to keep weight loss to a minimum.

Potatoes have a natural dormancy of 60-130 days (depending on the storage temperature). After that period, they will start to sprout. Some plant extracts, including clove oil, can add 20-30 days storage, and will then need to be reapplied. I do not know anything about this myself, and do wonder how you remove the clove flavor from the potatoes!

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Speaking Events

I have two speaking events coming up in September
Mother Earth News Fair

2019 Mother Earth News Fair Pennsylvania.

September Friday 13- Sunday 15, 2019
Location: Seven Springs Mountain Resort, 777 Waterwheel Dr., Seven Springs, Pa. 15622

I am giving two 60 min workshops

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

Lettuce Year-Round on Friday 9/13 12.30-1.30 pm at the Grit Stage

This presentation includes techniques to extend the lettuce season using row covers, cold frames, and hoop houses to provide lettuce harvests in every month of the year. The workshop includes a look at varieties for spring, summer, fall, and winter. Pam Dawling considers the pros and cons of head lettuce, leaf lettuce, baby lettuce mix, and the newer multileaf types. She also provides information on scheduling and growing conditions, including how to persuade lettuce to germinate when it’s too hot.

Cool Season Hoophouse Crops on Saturday 9/14 3.30-4.30 pm at the Building and Energy Stage

Learn how to fill your hoop house with productive food crops in the cool seasons. Pam Dawling discusses suitable crops, cold-hardiness, selecting crops, calculating how much to harvest and how much to plant, crop rotation, mapping, scheduling, seasonal transitions, succession planting, interplanting, and follow-on cropping.

Book-signing at the Bookstore Saturday 4.30-5 pm. Buy new books at the Bookstore and bring your grubby used copies to be signed too!

Demos at New Society Publishers booth, of tomato string-weaving and wigglewire system for fastening hoophouse plastic to framework
Friday 3 -3.30 pm, 4.30-5 pm; Saturday 10-11 am, 1.30-2.30 pm; Sunday 9-10 am. 1-2 pm, 3.30-4 pm

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Heritage Harvest Festival, Monticello, Charlottesville, VA

September Friday and Saturday 21-22, 2019
Buy tickets online
Workshop with Ira Wallace
10:30 – 11:30 am Saturday in the Heritage Tent

Winter Gardening: No Tech to High Tech 

Learn tips on growing cold-hardy vegetables (not only kale!) out in the open and with varying degrees of protection from rowcovers, low tunnels, coldframes and hoophouses (high tunnels). We’ll consider crop choices, planting dates and harvesting so there’s always something to eat for everyone from winter market gardeners to small backyard growers. We’ll explain ways to maximize production with succession planting and follow-on cropping.

 No extra fee for the workshop, included with the price of general admission

Booksigning: SATURDAY, SEPT. 21st, 11:45am – 12:15pm, MONTICELLO SHOP TENT (WEST LAWN). Buy new books at the Bookstore and bring your grubby used copies to be signed too!

December view in our hoophouse, showing lettuce mix and turnips.
Photo Wren Vile

Winter Kill Temperatures of Cold-Hardy Vegetables 2019

Baby greens in a cold frame in January.
Photo Southern Exposure Seed Exchange

I keep records of how well our crops do in the colder season, both outdoors and in our double-layer hoophouse. I note each increasingly cold minimum temperature and when the various crops die of cold, to fine-tune our planning for next year. We are in zone 7a, with an average annual minimum temperature of 0-5°F (-18°C to -15°C).  We had some extremely cold temperatures of -8°F and -9°F (-22°C and -23°C) in early January 2018. The winter of 2018-2019 was not as brutal. Our lowest temperatures were 6°F (-14°C) 1/31/19, 8°F (-13°C) 12/11/18 and a couple of 11°F (-12°C). This year I found that senposai is  more cold-tolerant than I had thought. otherwise I haven’t got much new news here. My results from other years hold up.

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, microclimates and rain levels may lead you to use different temperatures in your crop planning.

Hoophouse Notes

Our double-plastic 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; the plants recover in the warmer daytime conditions (it seems to be the night+day average temperature that counts);

Winter crops snug in our hoophouse in a December snowstorm.
Photo Pam Dawling

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

For example, salad greens in our hoophouse can survive nights with outdoor lows of 14°F (-10°C). Russian kales, lettuce, mizuna, senposai, spinach, tatsoi, turnips, 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 varieties for a solar-heated winter greenhouse or 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, Oscarde, 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.

Hoophouse lettuce Red Tinged Winter and Tango (and senposai) in our hoophouse in December.
Photo Pam Dawling

Outdoor killing temperatures of crops (unprotected unless stated)

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.

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 15°F (-9.5°C)), 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).

Closing rowcovers after a winter spinach harvest.
Photo Wren Vile

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, some turnips (Purple Top).

Using a sturdy digging fork to harvest leeks in December.
Photo Pam Dawling

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), Senposai leaves (the core of the plant may survive 8°F/-13°C), large leaves of savoyed spinach (more hardy than smooth-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.

Garlic shoots poking through the mulch in January.
Photo Pam Dawling

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).

0°F (-18°C): Chives, some collards (Blue Max, Winner), corn salad (mâche), garlic, horseradish, Jerusalem artichokes, Even’ Star Ice-Bred Smooth Leaf  kale, 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). 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

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

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

Many of our Vates kale plants survived those cold temperatures 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. I have no personal experience of this.

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

A hardy cover crop mix of winter rye, hairy vetch and Austrian winter peas.
Photo Bridget Aleshire

Hoophouses I visited this month

In early November, during the Carolina Farm Stewardship conference I went on the afternoon bus tour to see 10 high tunnels and how they’re used for season extension,  irrigation, disease control, pest protection, and trellising. Red Hawk Farm grows salads and greens year-round in six high tunnels (more under construction!), and sells primarily to local grocery stores and restaurants.  Funny Girl Farm grows produce year-round for its popular farmstand and CSA, with four high tunnels and a greenhouse.They were focusing on the sweet potato harvest outdoors when we visited.

Red Hawk Farm hoophouse densely planted with multileaf lettuces.
Photo Pam Dawling

At Red Hawk Farm I was astounded to see this whole hoophouse planted wall-to-wall with multileaf lettuces. No aisles! The farmer Brett Evans plans to harvest with a walk-behind motorized salad harvester machine that makes a 4 ft wide cut. Then he’ll leave the lettuces to regrow. He uses the paperpot transplanter  which I mentioned last week. Here are the starts growing in their propagation house.

Lettuce starts in paperpots at Red Hawk Farm.
Photo Pam Dawling

They still had peppers bearing well in one high tunnel

Early November pepper harvest at Red Hawk Farm.
Photo Pam Dawling

Another interesting feature was the opening roof vent, which I had not seen in operation on a hoophouse before.

Opening roof vent on a hoophouse at Red Hawk Farm.
Photo Pam Dawling

And this past week, I went to Potomac Vegetable Farms in northern Virginia for a talk with Future Harvest CASA members, and a tour of the hoophouses used there led by farmer Zach Lester.  I was interested in seeing the success he is having with caterpillar tunnels. These are smaller tunnels with a single layer of plastic, held in place by ropes, as you see in the photo below. They can be temporary or short-term, and Zach showed us one which is a “swing house” with two sites side by side, sharing one row of ground posts, and having just one row to move each time. Another way to deal with crop rotations and reduce the chances of pests and diseases!

Caterpillar tunnel at Potomac Vegetable Farms.
Photo Pam Dawling

At the ends, the plastic is gathered up and tied to well-anchored stakes, as you can see here.

How the ends of caterpillar tunnels are gathered and fastened to stakes.
Photo Pam Dawling

Zach got these frames custom made by Nolts. They have taller sidewalls than many models. He is also a firm believer in having a ridgepole in caterpillar tunnels, to reduce the likelihood of collapse with snow or high winds. As you can see here, they had some snow already.

Potomac Vegetable Farms caterpillar tunnel showing rolled up side.
Photo Pam Dawling

At both these farms, I learned the technique of laying landscape fabric along the side walls to reduce weed growth. You can burn holes in the landscape fabric where the ground posts go through, and it will keep the weeds away for a long time. I wish I’d known that technique when we put up our hoophouse. We have to hand weed, and in some places we have wiregrass (Bermuda grass) which has grown under the baseboards and even between the boards where there are joins.


Lastly, I have of course visited our own hoophouse at Twin Oaks, and have written a post for Mother Earth News Organic Gardening on Dealing with Snow on Your Hoophouse. So if it’s snowing where you are, you can click on the link to read about that.

Lettuce slideshow, Mother Earth News Fair, FaceBook Live, Top summer blogposts, upcoming events

We drove home seven hours from the Pennsylvania Mother Earth News Fair yesterday through the rain. The remnants of Hurricane Florence. We were among the lucky people. Earlier forecasts for Florence had the hurricane raging across central Virginia.

At the Fair, I gave two workshops: Fall and Winter Hoophouses and my new Lettuce Year Round, which you can view right here. Click the diagonal arrows icon to get a full screen view.

I had a bit too much material for a one-hour time-slot, so those of you who were there and felt disappointed at what I had to leave out, you can see it here.

While I as at the Fair I did a FaceBook Live Interview about gardening in hoophouses, with another author, Deborah Niemann. Look on Facebook for Deborah Niemann-Boehle or click the topic link above. She has several books: Raising Goats Naturally, Homegrown & Handmade, and Ecothrifty.

Shade cloth on a bed of lettuce in summer.
Photo Nina Gentle

Meanwhile, Mother Earth News tells me that my post 20 Tips for Success in Germinating Seeds in Hot Weather is in third place for most popular posts this summer.

The winner  An Effective and Non-Toxic Solution for Getting Rid of Yellow Jackets’ Nests by Miriam Landman got 43,328 views in 3 months!

Weeding rowcovered spinach in winter.
Photo Wren Vile

Looking at my own website statistics, I find that for this week, the most popular posts are

  1. Winter Kill Temperatures of Winter-Hardy Vegetables 2016
  2. Soil tests and high phosphorus levels
  3. How to deal with green potatoes
  4. .Winter-Kill Temperatures of Cold-Hardy Vegetables 2018
  5. Alliums for September

For all-time, the bias is naturally on posts that have been around longest,

  1. Garlic scapes! Three weeks to bulb harvest! Is most popular, followed closely by
  2. Winter Kill Temperatures of Winter-Hardy Vegetables 2016.
  3. How to deal with green potatoes is still #3.
  4.  The Complete Twin Oaks Garden Task List Month-by-Month,
  5. Harvesting Melons
  6. Book Review, Epic Tomatoes by Craig LeHoullier
  7. Wnter Hardiness
  8. Book Review: The Lean Farm by Ben Hartman and
  9. Setting out biodegradable plastic mulch by hand
Rolling biodegradable plastic mulch by hand
Photo Wren Vile

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I’ve updated my Events page again, now that the September- April  “Events Season” has hotted up. I’ve added in a couple of new ones and updated some others. Click the Events tab to find conferences and fairs near you, and be sure to come and introduce yourself!

Ira Wallace of Southern Exposure Seed Exchange, at the Heritage Harvest Festival Tomato Tasting.
Photo courtesy of Monticello

The Heritage Harvest Festival  is September 21-22 Monticello, near Charlottesville, Virginia

I’m giving a Premium Workshop on Friday Sept 21, 3-4 pm Classroom 7. Click the link HERE to book for that.

Feeding the Soil

In this workshop I will introduce ways to grow and maintain healthy soils: how to develop a permanent crop rotation in seven steps, and why your soil will benefit from this; how to choose appropriate cover crops; how to make compost and how to benefit from using organic mulches to feed the soil. Handouts.

Book-signing Friday 4.15 – 4.45 pm.

On Saturday there are events all day from 10am to 5pm. $26 general admission.

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Saturday September 29, 2018  Allegheny Mountain Institute Farm at Augusta Health,  Fishersville, VA 22939. 9 am – noon

I’m giving a two-hour Class on Season Extension, followed by one-hour Q&A teaching tour of the hoophouse and greenhouse.

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!

Sowing hoophouse winter crops

New spinach seedlings in our hoophouse.
Photo Pam Dawling

We are on our way with our late fall, winter and early spring crops in the hoophouse. On September 6 and 7 we sowed five crops in our first bed – spinach, tatsoi, Bulls Blood beet greens, radishes and scallions. On September 15 we sowed lettuces, chard, pak choy, Chinese cabbage, Tokyo Bekana and Yukina Savoy, in an outdoor bed to be transplanted into the hoophouse in a few weeks, after we’ve prepared another bed.

Broadfork from Way Cool Tools.
Photo Way Cool Tools

To prepare hoophouse beds for winter crops, we first remove the summer crops to the compost pile, then spread a generous layer of compost over the surface. We use about five wheelbarrowsful for one bed 4’ x 90’. Next we move the three lengths of drip tape off to one side or the other, and broadfork the whole area. We have an all-steel broadfork from Way Cool Tools that we really like. To use a broadfork, work backwards either going the length of the bed or the width. Stab the tines into the soil and step on the crossbar, holding the long handles. Step from foot to foot until the bar touches the soil, with the tines all the way in, then step off backwards, pulling the handles towards you. This loosens a big area of soil, which hopefully crumbles into chunks. Lift the broadfork and set it back in the soil about 6” back from the first bite. Step on the bar and repeat. We’ve found it’s important to only broadfork the amount of space you have time to rake immediately, otherwise the warm hoophouse conditions dry out the soil and make it harder to cultivate into a fine tilth, which is the next task. Sometimes we use a rake, breaking the clumps up with the back of the rake, then raking the soil to break up the smaller lumps, and reshape the bed.

7″ stirrup hoe.
Photo Johnnys Selected Seeds

Sometimes we use a wide stirrup hoe very energetically. This isn’t the job scuffle hoes were designed for (that’s very shallow hoeing, and hence why we call them scuffle hoes), but the sharp hoe blade does a good job of breaking up clumpy soil. We’ve also found it important to lay the drip tapes back in place in between each day’s work, so that the soil gets irrigated when we run the system and stays damp. We don’t want dead, baked soil.

Once the bed is prepared, we measure out the areas for different crops and mark them with flags. Next we use our row-marker rake (bed prep rake) from Johnny’s Selected Seeds.

Johnny’s Bed Prep rake with row marker pegs.
Photo Johnnys Selected Seeds

We plant crops closer in the hoophouse than outdoors, and closer to the edges of the beds. We don’t have many weeds in the hoophouse, and the paths are marked off with twine, to keep us from stepping on the beds, compacting the soil. We find that the soil does slump and compact some of its own accord, even if we don’t step on the edges (and of course, some feet do find themselves on the bed edges sometimes), hence the once-a-year broadforking. We found out how valuable the soil loosening is, because one year before we started broadforking, we decided to loosen the edges with a digging fork to make up for several years of accidental steps. The edge rows of spinach grew much bigger than the inner rows, and we realized that the whole bed needed loosening.

After the rowmarking, we deepen the furrows if needed (often it’s not needed), using a pointed hoe, then sow the seeds. We pre-sprout our spinach for a week in a jar in the fridge. Just soak the seed overnight, drain it in the morning, fit a mesh lid on the jar, and lay it on its side in the fridge. Once a day, give the jar a quarter turn to tumble the seeds and even out the moisture. This year the seeds were a bit wet when I came to sow them, and clumped together. I poured them out on a cloth to dry a bit before I sowed. This year we are growing two varieties (Avon and Reflect) side by side, still seeking a replacement for our much loved Tyee, which was pulled from the market, because it was prone to a disease prevalent in the West.

Easter Egg radish seedlings in our hoophouse.
Photo Pam Dawling

The spinach, tatsoi and radishes came up very quickly, with the beets a day or two behind. The scallions came up in a week, which is quicker than at other times of year.

One week after the sowings, I thinned the spinach and radishes to 1” apart in the row. We are growing Easter Egg, Cherry Belle and White Icicle radishes. The Cherry Belle will be ready first, Easter Egg next (they mature relatively gradually, giving us a nice harvest period). Icicle are unusual long white radishes which are slower to mature, and slow to get woody.

Buckley One-cut (Eazileaf) lettuce.
Photo High Mowing Seeds

Meanwhile, outdoors on September 15 we sowed the first half of the crops that we transplant bare-rooted into the hoophouse. Our planned schedule called for 10 varieties of lettuce, but I ended up sowing 12, partly because we are trying three new Vitalis one-cut lettuce varieties from High Mowing Seeds: Ezrilla, Hampton and Buckley.  These are bred to provide lots of similar-sized leaves from cutting. They can be cut and mixed for baby salad mix or cut as whole heads for easy-to-prepare salads, or harvested by the leaf (or layers of leaves) once the plant has grown to full size. This is how we use them. They were previously called Eazileaf varieties, and are now called One-cut lettuces. They are only available as pelleted seed, so I regard them as too pricey to grow for baby salad mix, and best used for multiple harvests.

Johnny’s Green Sweet Crisp Salanova lettuce.
Photo Johnnys Seeds
Osborne’s Multigreen 3 lettuce.
Photo Osborne Seeds

You can click here to read the New Head Lettuces article Andrew Mefferd wrote about this new type of lettuce in Growing for Market magazine. We have previously grown Johnny’s Salanova and Osborne’s Multileaf varieties and I wrote about them here and here. This year we are trying the High Mowing ones. We did a small trial of them outdoors in spring, knowing that in our climate (very different from High Mowing’s in Vermont) they might well bolt. They grew into handsome plants, but clearly they are more suited to fall than spring in our quickly-heating-up climate.

Other lettuces we sow for our winter hoophouse crops include Oscarde, Panisse, Tango which have a similar shape of lots of same-sized leaves, and Green Forest (romaine), Hyper Red Rumpled Wave, Merlot, Revolution, Salad Bowl and Red Salad Bowl. I would have sown Red Tinged Winter but we seem to be out of seed.

Red Salad Bowl lettuce.
Photo Bridget Aleshire

Year Round Lettuce

I’ve now completed 12 monthly posts about suitable lettuce varieties and growing techniques. You can see these by clicking the Lettuce Varieties Category tab, but you can also get the overview here. They run from May to April because that’s how I wrote them. Click the name of the month to view the original post.

Sword Leaf Lettuce
Photo Southern Exposure Seed Exchange

May: Sword leaf lettuce

Star Fighter lettuce.
Photo Johnnys Selected Seeds

 

 

 

 

 

 

 

 

June: Starfighter: Lettuce Variety of the Month

 

 

 

 

 

 

 

 

Bed of young Green Forest lettuce.
Photo by Wren Vile

July: Green Forest – Lettuce variety for early July

Pablo Batavian lettuce
Photo Nina Gentle

August:Batavian lettuces for August

Freckles lettuce is a cheering sight in spring or fall.
Credit Kathryn Simmons

September: Lettuce in September,

Young lettuce plants in greenhouse beds in October. Photo by Bridget Aleshire

October: Lettuce growing in October

Starfighter and Red Salad Bowl lettuce in our hoophouse.
Photo Wren Vile

November: Lettuce in November

Rouge d’Hiver hardy romaine lettuce.
Photo Bridget Aleshire

December: Lettuce in December

 

 

 

 

 

 

 

Newly germinated lettuce seedlings.
Photo Kathryn Simmons

January: Lettuce varieties for January, new year, fresh start

Reliable Red Salad Bowl lettuce, one of our standbys.
Photo Bridget Aleshire

Extra: Lettuce Varieties for 2017

Baby lettuce mix in our hoophouse in winter.
Photo Twin Oaks Community

February: Lettuce in February

Bronze Arrow lettuce is a beautiful and tasty early spring variety.
Photo Bridget Aleshire

March: Lettuce for March and all year

April: Lettuce in April

Spring lettuce bed.
Photo Wren Vile

Our Vegetable Gardens in May, Year Round Lettuce, Sprouts and Salads

Spring cabbage planted in hay mulch, a few weeks after transplanting.
Photo Kathryn Simmons

Our broccoli and cabbage transplants enjoyed the cool rainy weather and got through the dry hot weather. Yes, it’s been very changeable. Last night the temperature dropped to 33F (0.5C).  We’re harvesting rhubarb, kale, spinach, collards, senposai and garlic scallions outdoors, and are deep into our garlic scape harvest.

Pulling garlic scapes in May
Photo by Wren Vile
How to harvest garlic scapes.
Photo Wren Vile

The above photo shows our preferred garlic scape harvest method: grasp the scape firmly below the head and pull steadily directly upwards. There will be a popping sound when the stem breaks. This method gets us the largest amount of the scape, and more importantly, the lower part is the most tender, and we don’t want to leave it behind.

Flowering squash plants with a row of snap peas in our hoophouse.
Photo Wren Vile

In our hoophouse we are harvesting the last of the winter scallions, some snap peas and today, May 9, the first yellow squash (Gentry). You can see in this photo taken last week, that the squash are flowering and have tiny fruits developing.

Our first bed of outdoor lettuce (and weeds!) Photo Wren Vile

My Mother Earth News Organic Gardening blogpost about Growing Lettuce Year Round: Succession Planting for a Continuous Supply is up. This acts as a follow up to one of my workshops at the Asheville MEN Fair last weekend on Succession Planting for a Continuous Supply of Vegetables.

I had a good time at the Fair. My Saturday workshop on Sweet Potatoes was addressed to a full tent of extremely hardy sweet potato lovers. The weather was cold and windy, especially hard on speakers – at least the audience sat shoulder-to-shoulder for warmth. I was glad to get indoors for the book-signing afterwards. My Sunday workshop on Succession Planting was the last session of the Fair, but even so, there was good attendance.

My fellow Twin Oaker Winnie has written about using our seasonal vegetables in her blog

sustainexistence. Check out her Beet, Spinach, & Garlic Scape Salad

Beet, Spinach and Garlic Scape Salad

Lettuce in April

Spring lettuce bed.
Photo Wren Vile

We’re on the brink of starting to harvest our first outdoor lettuce, switching over from the last of the baby lettuce mix in the hoophouse. Our goal for this transition is April 15, but naturally the exact date will depend on the weather in the spring, the coldness of the late winter, the rate at which we are eating lettuce and other factors beyond the grower’s control.

Hoophouse baby lettuce mix. Photo Kathleen Slattery

We make three sowings of baby lettuce mix: 10/24 to harvest early December to early March (after we’ve cut it several times, and it is starting to tun bitter); 12/31 to harvest from late February till the end of March Later if it doesn’t get bitter from hot weather); and 2/1 to harvest mid March to the end of April. This year the #2 sowing is still edible in mid April, so we have two patches feeding us for a little longer.

Our winter salad mixes are very popular, but we can only continue with those as long as the spinach and the salad brassicas hold up. Part of me is always sad to stop eating salad mix, but the other part welcomes the juicier, crunchier, tastier head lettuce. Baby lettuce mix is very pretty, but honestly I find it a bit short on flavor and texture! It’s the other ingredients in the salad that make it interesting for me, especially spinach.

The first outdoor lettuce were sown 1/17, planted out 3/9, to feed us 4/15 to 5/8, when the second sowing should be ready. We cover these with rowcover on hoops when we transplant, for about a month, or until the weather seems settled at a reasonable temperature.

Our raised beds outdoors are 4 ft wide, with 1 ft paths. we plant four rows of lettuce, spaced 12″ apart, and plant about 120 from each sowing. That usually fills a third of a 90 ft long bed, so we have 3 different plantings in each bed of lettuce. We continue at this pace until our last outdoor plantings around the fall equinox.

This spring we are going to continue the salad mixes a bit longer by harvesting the outdoor lettuce by the leaf. We have lots of really good looking spinach to mix in, and the last few mizuna and ferny mustards. We used to only sow these twice, 9/24 to transplant in the hoophouse, and 11/9, which feeds us until late March. We added in a third sowing of mizuna and ferny mustards 2/1 which we harvest 3/24 to 4/23 approximately. That extra month is really worth having!

We also have a short row of Sugar Ann snap peas in the hoophouse (sowed 2/1) that we like to snip into thirds and add to salad mix. This makes for a nice little surprise for everyone. We couldn’t feed a hundred on 50 ft of snap peas! These are an incentive to keep the salad mixes going while the peas are being harvested.

Sugar Ann snap peas in our hoophouse, a month earlier than outdoor peas.
Photo Bridget Aleshire