outdoor nursery seedbed – Sustainable Market Farming

Spring Lettuce Transition

Our first outdoor lettuce bed in May.
Photo Wren Vile

We grow lettuce to harvest year round, here in central Virginia. From the end of April into November, we harvest lettuce heads outdoors, from our raised bed area. From October to early March we harvest outer leaves from leaf lettuces and romaines in our solar greenhouse, and in our solar-heated double-layer hoophouse from October to April. From mid-November we harvest salad mixes containing lettuce from our hoophouse. From 4 December to late May we have baby lettuce mix from the hoophouse. Note that we have overlaps at both spring and fall transitions. We’re approaching the spring transition, and that is what I am going to focus on in this post.

Our Winter Hardiness Zone in central Virginia is 7a, which means our annual minimum temperature averages 0°F to 5°F (-18°C to -15°C). Our average date of the last spring frost over the past 14 years is April 29 (later than 5/13 one year in 10).

Flats of lettuce transplants in our cold frame in April.
Photo Pam Dawling

More About Growing Lettuce

See my post Lettuce All Year in a Changing Climate, which includes links to my slideshow about growing lettuce year round, and our updated Lettuce Varieties list and Lettuce Log (planting schedule). It also includes keys to succeeding with year-round lettuce (dates for succession planting) and what causes bolting.

I have lots of posts about growing lettuce! Here are some of them:

Early Lettuce Production See this post for details of growing lettuce transplants in flats in our greenhouse.

Cold Tolerant Lettuce – In the 2017-2018 winter we had some extremely cold weather, with outdoor night-time temperatures of -3°F (-19°C) two nights, followed by -8°F (-22°C) 6 and -9°F (-23°C). Our guideline is that if we expect the night-time low to be 8°F (-13°C) or lower outdoors, we use rowcover in the hoophouse. It wasn’t enough to save all the lettuce. See this post for which varieties survived.

Ezrilla, a favourite cold-hardy lettuce.
Photo Wren Vile

Also see What makes vegetable crops bolt and how can I stop it?

And I have a whole year of Lettuce for the Month posts. See here for the overview. These posts are mainly about our favorite varieties for each time of year.

Head Lettuce Transplanted Outdoors

From February to November/December, we grow lettuce outside from transplants. Transplanting gets a head start on weed control, which is important all the way from planting out to a couple of weeks before harvest. Don’t waste time hoeing lettuce you will be harvesting next week. I generally find that if we hoe once, a couple of weeks after transplanting, that is all the weed control we need at the fast-growing time of year.

From mid-January until mid-March we sow in flats in the greenhouse, with heating for the January-March sowings, to get the seeds germinated, then good old solar energy to grow them to transplanting size. We spot the seedlings out to give the plants more space, and harden off the flats of transplants in our cold frame for two weeks before planting them in the garden. The first few plantings will get rowcover after transplanting, to protect the young plants from cold and speed up the growth rate. March 9 is our goal for transplanting our first sowing (January 17) outdoors. January 17 to March 9 is 52 days, a very long time for the seedlings to grow to transplant size! We hope to harvest that first lettuce as heads in late April.

During April we put the seed flats in the greenhouse without extra heating, as temperatures in the greenhouse are warm enough to germinate the seeds. Growth speeds up, and in warm weather we transplant three weeks after sowing. The intervals between one transplanting date and the next decrease from 9 days in spring to 5 or 6 days in summer. We transplant 120 lettuce from each sowing – about one week’s worth for 100 people.

Swordleaf lettuce, and an unnamed romaine with radishes. Photo Bridget Aleshire

Soil Temperatures for Lettuce Germination

The soil temperature range for germination of lettuce seeds is 35-85°F (2-29°C), with 40-80°F (4-27°C) being the optimum range and 75°F (24°C) the ideal. At 41°F (5°C) lettuce takes 15 days to germinate; at 50°F (10°C) it takes 7 days; at 59°F (15°C) 4 days; at 68°F (20°C) only 2.5 days; at 77°F (25°C) 2.2 days. Then the time to germination increases: 2.6 days at 86°F (30°C); after that it’s too hot. A soil thermometer soon pays for itself and saves lost crops and frustration.

Summer Lettuce Nursery Seedbed with Concept, De Morges Braun, New Red Fire and Loma lettuces.
Photo Bridget Aleshire,

Bare-Root Transplanted Lettuce in Summer

From May to late September we use an outdoor nursery seedbed and do bare-root transplants (with heat-tolerant varieties). The soil temperature does not vary as much as the air temperature, and we no longer worry about cool nights.

If it’s too hot for lettuce seed to germinate, you can find a cooler place (put a seeded flat in a plastic bag in the fridge or on the concrete floor in the basement). Or cool down a small part of the world. From June we put shade-cloth over the lettuce seedbed, and only sow in the evening. In July and August, we water the sowed seedbed with freshly drawn cold water, line up ice cubes along the seed rows, and cover with shade cloth.We make sure to keep the seedbed damp, using cold water each time.

See Using ice to germinate lettuce seed in hot weather

From July to September we sow lettuce every 5 days! See Success with summer lettuce. Of course, transplanting that lettuce in hot weather takes care too. We do that late in the day, and water as we go. We cover the transplants with hoops and shade-cloth, and water daily until they are well established. We stop sowing for outdoors on August 29.

If using a nursery seed bed, you can put ice cubes on top of rows of seeds in hot weather to help cool the soil.
Photo Bell Oaks

Lettuce After Summer Ends

From September 11-17 we sow lettuce in a nursery seedbed to transplant in our greenhouse, and on September 15 and 24 to transplant in our hoophouse. This is our fall transition and I’ll write about that when the time comes.

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.

Batavian lettuces for August

Cherokee Red Batavian lettuce sowed in August. Photo Bridget Aleshire — Cherokee Red Batavian lettuce sowed in August.
Photo Bridget Aleshire

This is the hardest time of year for growing lettuce in our part of the world. Lettuce seed needs temperatures below 86F (30C) to germinate. That’s the highest soil temperature that lettuce seed is viable at. Higher than that and heat dormancy sets in. It takes 2.6 days at 86F (30C), which is longer than the 2.2 days at 77F (25C), and equals the time it takes at 68F (20C). Naturally, because these are average figures, varieties vary in their ability to germinate at high temperatures. You’ll want to choose heat tolerant varieties anyway, or they will just bolt (grow up to flower and seed) rather than form a head. Among the heat tolerant ones, the romaine Jericho and the Batavians are best able to germinate at high temperatures.

Cherokee is our new favorite among the Batavians, because of its wonderful dark red color. All Batavians have relatively thick juicy, crunchy leaves, and a heavy head. Our old favorite Pablo, is green tinged with red. (This photo and the Cherokee are of half-grown lettuces, not full-size). Pablo is available from Southern Exposure Seed Exchange

Pablo Batavian lettuce Photo Nina Gentle — Pablo Batavian lettuce
Photo Nina Gentle

Cardinale Batavian lettuce. Photo Swallowtail Garden Seeds — Cardinale Batavian lettuce.
Photo Swallowtail Garden Seeds

Cardinale is redder than Pablo, but less so than Cherokee. Swallowtail Garden Seeds has a selection of seven Batavian lettuces (also called summer crisp lettuces), including Cardinale and a couple I have not tried (Red Ball Jets and Jester).

Carioca Batavian lettuce. Credit Johnnys Seeds — Carioca Batavian lettuce.
Credit Johnnys Seeds

Carioca is another red on green, less red than green. It was sold by Johnnys, but is now available from Restoration Seeds

Magenta Batavian lettuce. Photo Johnnys Seeds — Magenta Batavian lettuce.
Photo Johnnys Seeds

Magenta is another darker red Batavian lettuce, sold by Johnnys.

Young Sierra lettuce. Photo Bridget Aleshire — Young Sierra lettuce.
Photo Bridget Aleshire

Sierra Batavian lettuce. Photo Southern Exposure Seed Exchange — Sierra Batavian lettuce.
Photo Southern Exposure Seed Exchange

Among the greener Batavians, we like Sierra from Southern Exposure who rate Sierra as taking 54 days. “Open-headed batavian crisphead with excellent resistance to bottom rot and tip-burn. Leaves are glossy green with reddish veins. Grows in open fashion at first, forming a compact head at maturity. Very tasty, crisp, and juicy. Holds well under high heat.”

Nevada Batavian lettuce. Photo Swallowtail Garden Seeds — Nevada Batavian lettuce.
Photo Swallowtail Garden Seeds

Nevada is an all-green Batavian we really like. It’s available from Swallowtail Garden Seeds who note “outstanding, juicy nutty flavor – it is among the best tasting of all lettuces”

Concept Batavian lettuce Photo Johnnys Seeds — Concept Batavian lettuce
Photo Johnnys Seeds

Concept is another green Batavian that has done well for us. It’s available from Johnnys, Swallowtail Garden Seeds Like several of the Batavians, at an adolescent stage the head is open, but at maturity it whorls around and closes up.

Loma Batavian lettuce. Photo Southern Exposure Seed Exchange — Loma Batavian lettuce.
Photo Southern Exposure Seed Exchange

Loma from SESE is a smaller, dense, fast-growing spiky-leaved Batavian. This is one of the varieties I choose when I am a day or two late sowing, and I want fast-growing varieties to make up for my slackness. Ready in 49 days.

Muir Batavian lettuce. Photo Johnnys Seeds — Muir Batavian lettuce.
Photo Johnnys Seeds

We also grow Muir, from Johnnys, who say “the slowest to bolt in our summer trials. . . . the light green, extra wavy leaves form dense heads at a small size and can be harvested as a mini or left to bulk up into large, heavy, full-size heads.”

Mottistone spotted Batavian letuce. Photo Johnnys Seeds — Mottistone spotted Batavian letuce.
Photo Johnnys Seeds

Another less-typical Batavian is the spotted Mottistone, also from Johnnys. We used to grow this one, but there’s something about spotted lettuce in the summer that just didn’t appeal to people. They thought it was diseased, rather than fancy! it does have good flavor.

Anuenue Bataviasn letuce. Photo Southern Exposure Seed Exchange — Anuenue Batavian lettuce.
Photo Southern Exposure Seed Exchange

Anuenue, from SESE comes from the University of Hawaii. Anuenue is Hawaiian for “rainbow” (pronounced “ah-nu-ee-nu-ee”).] The seed is able to germinate at higher soil temperatures. We like this one (which is more like icebergs than the other Batavians are) as a change from our old reliables.

Lettuce seedbed. Photo by Bridget Aleshire — Lettuce seedbed.
Photo by Bridget Aleshire

And now, back to how we actually get the lettuce seed to grow in summer. We use an outdoor nursery seedbed, sow the seeds at the end of the day, as temperatures drop, water with cold water, line up ice cubes on the soil covering the seeds, cover the seedbed with shade cloth, and then water daily with fresh-drawn cold water until we get germination. Sunflowers provide shade but also suck up a lot of water, so don’t get too close. Sheep sculptures are optional.

Garlic harvest, Intercropping, Summer lettuce,

Well, it’s really hot here – see the AccuWeather page on the Dangerous Heat Wave. Since June 1st we’ve had 9 days of 95F or more, including two at 97F and today is forecast to be the hottest yet. Tropical Storm Bill only gave us 0.7″ – I’m looking forward to the trough predicted for next weekend, although I should be careful about what I wish for. It might bring record low temperatures for the time of year, and such whacky yo-yos of conditions are hard on us as well as our crops.

OLYMPUS DIGITAL CAMERA — Cured garlic being removed from the drying nets to be trimmed and sorted. Photo Wren Vile

Our garlic is all drying in the barn, with fans and in a few days we expect it to have dried down enough for us to start trimming and sorting. We usually do that in the afternoons, as it’s indoors and includes fans.

If you live in a cooler zone, you might be wondering when to harvest your garlic. Margaret Roach has a great article on determining garlic maturity on her blog A Way to Garden. Her harvest time is 7 or 8 weeks after ours. She has a whole set of articles on growing, harvesting and curing garlic. One sign of maturity that I don’t think Margaret mentions, that we use with our hardneck garlic is to dig a few sample bulbs, and cut them in half horizontally. If the bulbs are ready, there will be small air spaces open between the remains of the stem and the cloves.

I just posted an article about Intercropping Vegetables in Late Spring and Early Summer, aka Relay Planting on the Mother Earth News Organic Gardening Blog. Depending where you live these ideas might be very timely, or else suggestions to consider in your planning for next year. Interplanting, intercropping, or relay planting, is a version of companion planting where the second crop is planted while the first is still growing. The goal is to get maximum use of the space, double use of any crop protection such as rowcover or shadecloth, (or irrigation) and let one round of hoeing clean up two crops.

We have successfully planted peanuts in the middle of a bed of romaine and small Bibb lettuces transplanted around the same date the peanuts are sown. We have also transplanted okra in the center of a bed with two rows of early spring cabbage. As the plants grow, we remove outer leaves of the cabbage that might overshadow the okra. Soon the okra is tall and the cabbage is being harvested. Two crops in one season, with no tilling needed between the two.

Cow Horn okra. Photo Kathryn Simmons — Cow Horn okra.
Photo Kathryn Simmons

This year we planned to transplant the okra in a spinach bed. The spinach came to an early end, but the okra is doing very well, and we have just started harvesting it, a bit earlier than in other years.

Today, despite the heat, it’s the day for sowing lettuce. At this time of year it’s often the day for sowing lettuce! Every 5 days. Success with summer lettuce is hard-earned. From May to late September I use an outdoor nursery seedbed and do bare-root transplants of heat-tolerant varieties. The soil temperature does not vary as much as the air temperature, although it does get warm! My hot weather lettuce sowing trick is to wait till the last half-hour before sunset, Sow the lettuce seed in the nursery bed, draw the soil over to cover the seed, and tamp it down, water it with fresh drawn water (cool from the well, not siting around all day in a can). Then I put ice on the lettuce seed rows! Crushed ice is easiest, but these days I just line up ice cubes where the rows are. Then I put a piece of shade-cloth over the planting. I make sure to keep the seedbed damp, using cold water each time.

Of course, transplanting lettuce in hot weather takes care too. I do that late in the day, and water as I go. I cover the transplants with hoops and shade-cloth, and water daily until they are well established. here’s the lettuce log I am using this year.

Colorado potato beetles, germinating lettuce, wheelhoes

A ladybug on a potato leaf, looking for pests to eat Photo Kathryn Simmons — Not a Colorado potato beetle: A ladybug on a potato leaf, looking for pests to eat
Photo Kathryn Simmons

Our spring-planted potatoes are just starting to flower, and I’m now in my weekly routine of monitoring for Colorado potato beetles. I walk the length of the patch and back, switching rows every 9 paces or so. I squish and count the adult CPB, and also count the larvae (I don’t always squish all of those). Did you know you can tell a squashed female CPB from a squashed male? The females are full of orange eggs, until you squash them, that is, then the orange eggs are all over your fingers!

Potato plants can tolerate 30-40% defoliation early in life, 10-60% defoliation during middle age, and up to 100% defoliation at the end of the season without reducing the yield.So don’t panic! But do pay attention. The Action Level for Colorado potato beetle is 1 adult per plant, and that for larvae is 2 per plant. Our rows are 265 ft this year, and the plants are 12″ apart, so I’m looking at 530 plants when I go down and back. So far, we’re doing great. Last week I found 12 adults. This week I found 5 adults and 41 larvae. I still don’t need a mass slaughter program. If we need to spray I’ll use Spinosad. For home gardens you can buy Monterey Garden Insect Spray from Seven Springs Farm in Virginia. Or elsewhere. It is OMRI approved but is very toxic to bees (and Eastern Oysters, should you need to know), so we only spray Spinosad at dusk when the bees have gone home, and make sure not to pour the rinse water from the sprayer into the drains (which go via our septic system into the creek). Generally I use the driveway as a large inert area to spread the wash water over.

But I only use Spinosad if we have to. Another part of my plan is timely mowing of the clover patch next to the potatoes. The clover mix was undersown in the fall broccoli last year, and in the spring we simply bush hog that patch every time the weeds are getting too successful compared to the clover. Or ideally, before that happens. We had flowering crimson clover there earlier, and mowed that. Now what we see is white clover. there is red in the mix too, but I haven’t seen that flowering yet. Our hope/plan is that when we mow the clovers, many of the beneficial insects move over to the potato patch and eat the CPB.

At the great link I gave earlier, Andrei Alyokhin provides good information on the life cycle of the CPB, lots of resources, and a lovely collection of Colorado potato beetle haiku (traditional Japanese poetry) written and illustrated by Mrs. O’Malley’s second-grade students from the Old Town Elementary School in 2008 or so, somewhere in Maine I think. The poetry gives new perspectives as we walk the rows searching for the wee beasties.

Germinating lettuce seed

Some weeks I wonder what to blog about. This week I was helped by a neighboring grower who asked me questions about how I germinate lettuce. Aha! A timely topic! We try to grow lettuce for harvest all year round, here in central Virginia, and exactly how we do that varies with the season.

New flats of lettuce seedlings Credit Kathryn Simmons — New flats of lettuce seedlings
Credit Kathryn Simmons

From January until mid-March I sow in flats in the greenhouse, with heating to get the seeds germinated, then good old solar energy to grow them to transplanting size.

From mid-March to the end of April I sow in flats in the greenhouse, without extra heat.

Spring lettuce bed. Photo Wren Vile — Spring lettuce bed.
Photo Wren Vile

From May to late September I use an outdoor nursery seedbed and do bare-root transplants (heat-tolerant varieties). The soil temperature does not vary as much as the air temperature, so I don’t worry about cool nights.

From June I put shade-cloth over the lettuce seedbed, and only sow in the evening.

In July and August I put ice on top of the newly sown rows, under the shade-cloth.

baby lettuce mix in the hoophouse. Photo Twin Oaks COmmunity — Baby lettuce mix in the hoophouse.
Photo Twin Oaks Community

After that I sow lettuce mix in the hoophouse. (Click the link to see my Hoophouse in Fall and Winter slideshow.)

There’s a chart of germination at various temperatures in Nancy Bubel’s New Seed Starter’s Handbook and in the Knott’s Handbook for Vegetable Growers which is all online.The soil temperature range for germination of lettuce seeds is 35-85F, with 40-80F being the optimum range and 75F the ideal soil temperature. At 41F (5C) lettuce takes 15 days to germinate; at 50F (10C) it takes 7 days; at 59F (15C) it takes 4 days; at 68F (20C) only about 2.5 days; at 77F (25C) 2.2 days. Then time to germination increases: 2.6 days at 86F (30C); after that it’s too hot.

A soil thermometer soon pays for itself and saves lost crops and frustration. If it’s too hot, find a cooler place (put a seeded flat in a plastic bag in the fridge or on the concrete floor in the basement). Or cool down a small part of the world. That’s what I do when I sow in the evening, water with freshly drawn cold water, line up ice cubes along the seed rows, and cover with shade cloth.

And finally, to a tool we use a lot at this time of year (when the weather is dry enough for hoeing to be successful): our Valley Oak Wheel Hoes. We have two, both with pneumatic tires (rocky soil jars your wrists, think long-term). We have one with the standard 8″ blade and one with a 10″ blade. We use them for the aisles in our raised beds, for between rows of corn, anywhere without mulch. They are very energy efficient, compared to a hand hoe. And some of the crew treat he opportunity to wheel hoe as a chance for an aerobic workout. Others use a more moderate speed.Cover more ground with less effort, and hence, get more done before the weeds get too big to hoe.

The handlebar height is readily adjustable, the blade assemblies can easily be switched from one tool to another (buy one wheelhoe and several different width blades), there are other attachments such as a small furrower, a one-sided hiller and a 3-tine cultivator. And there are plenty of replacement parts available: we just ordered spare blades after wearing ours down to narrow strips.