lettuce mix in the hoophouse – Sustainable Market Farming

December lettuce and spinach in our hoophouse. Photo Wren Vile

Recently I traveled to Fayetteville, Arkansas to give my presentation Extend Your Growing Season into Colder Weather with High Tunnels. Run the mouse over the slide and click on the lower left.

CAFF - Extend Your Growing Season into Colder Weather with High Tunnels

We are getting ready for fall and starting to plant our winter crops in the hoophouse.

I have written about transition to winter crops here: Planning and Growing Winter Hoophouse Vegetables (August 16, 2022). This post includes a bed plan, and links to lots of related posts, such as selecting and planning winter crops, bed prep, direct sowing and transplanting, and then caring for the crops, optimizing use of the space, harvesting, and what to do if something goes wrong,

Fall Lettuce Transition

From September 11-17 we sow 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.

On September 15 and 24, we sow leaf lettuces and romaines in an outdoor nursery bed. We transplant these into our hoophouse at 10” (25 cm) spacing. This is a bit closer than the 12” (30 cm) spacing we use outdoors. We will harvest outer leaves from the hoophouse lettuce all winter, so the plants won’t get as big as they do outdoors.

Beautiful baby lettuce mix in our hoophouse in February.
Photo Wren Vile

On October 23 we start sowing lettuce mix in the hoophouse. Baby lettuce mix can be ready in as little as 21 days from mid-spring to mid-fall, longer in colder weather. Our first sowing will be harvestable form 4 December to 15 May if we’re lucky, although if it gets too hot, this planting will get bitter and we’ll need to pull it up.

Baby lettuce mix is a direct-sown cut-and-come-again crop, the plants regrow and can be harvested more than once in cool seasons. We sow 10 rows in a 4’ (1.2m) bed, 4.5” (11cm) apart. Weed and thin to 1″ (2.5 cm). When 3″–4″ (7.5–10 cm) tall, cut 1” (2.5 cm) above the soil. Gather a small handful in one hand and cut with using large scissors. Immediately after harvesting, weed the just-cut area so the next cut won’t include weeds. Rake after harvest with a fine leaf rake to remove outer leaves and cut scraps. If you want to make more than one cut, you will need to remove anything that isn’t top quality salad while you can see it. Larger scale operations have harvesting machines.

We make four or five sowings of baby lettuce mix, sowing our last one on 15 February, for harvest starting mid-March, and ending in May when it gets too hot. By then we should be happily harvesting juicy lettuce heads outdoors and will have lost interest in the lettuce mix.

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 time to germination increases: 2.6 days at 86°F (30°C); after that it’s too hot.

Removing Shadecloth from our Hoophouse

We are now removing our shadecloth. Normally we would have removed the shade cloth in mid-September, or at least by the Equinox, but this year we are delayed a week. After 15 years with our initial piece of shadecloth we ordered a new piece. Well, we ordered two new pieces, because we mistakenly ordered a piece only half long enough. We bought a matching piece for the other half, and this winter we are going to sew the two pieces together with nylon twine, because the ends of each piece roll back, leaving a central gap about 6 feet long by September. Measure twice, order once!

Our hoophouse with two pieces of shadecloth (by mistake). Photo Pam Dawling

Before next spring we need to replace quite a lot of the hooks the shadecloth ropes attach to. Next time we replace the big plastic we also need to replace the baseboards, as they are rotting and not holding the hooks well.

My post Fall hoophouse bed prep and shadecloth removal includes spreading compost, broadforking, and a step-by-step guide to hoophouse fall bed prep.

Also see September in the Hoophouse for more about removing shadecloth

A reader passed on this tip: “When I ordered shadecloth for my hoophouse, I overshot each end by ten or twelve feet. We stake that out on either end, using six-foot T-posts, to give us a shaded area where air moving into the hoophouse’s open ends can be cooled before entering the structure. Every year in July and August, I’m grateful we did.”

Washing Down the Salts in the Hoophouse

Effects of excess soil salt levels on crop foliage.
Photo Rose Ogutu, Horticulture Specialist, Delaware State University

Next week we will leach the salts that have risen to the surface of the soil and dried out there. My book The Year-Round Hoophouse has a whole chapter on recognizing, monitoring and reducing salts that have built-up in the hoophouse, and reducing the likelihood of problems in the future. There is also a chart of salt tolerance of various vegetables, so you can choose what to grow while you remediate your soil. Here I’ll just give a very short intro, in three slides. Click in the lower left of the first slide to move to the next one.

Salt Build-up

Closing Hoophouse Doors and Windows at Night

We are starting to close the doors at night when the temperature looks likely to drop below 50°F (10°C) outside. We had to trim down the grass to be able to push the doors to. We had to re-drill the holes the door-bolts (“cane bolts”) go down into. The doors have been wide open all summer.

View through the hoophouse doors in December.
Photo Kathleen Slattery

In fall/winter/spring, if night time outdoor low temperatures will be below 40°F (4.5°C) here, we close the windows as well as the doors.

See my post Hoophouse Sliding Doors if you might want to replace your doors with sliding ones.

One of the sliding doors on our hoophouse.
Photo Pam Dawling

Be Ready for Winter

See my post Dealing with winter weather in your hoophouse (Jan 2022). Be ready to deal with snow and strong winds, extra cold temperatures, and holes in the plastic letting cold air in. If you have a double layer hoophouse, the air inflated between the layers adds strength to the structure, as well as thermal insulation. Holes are bad news.

Hoophouse snow scraping tool on a telescoping painter’s pole. Photo Pam Dawling

Winter Kit

SnoBrum and telescoping painter’s pole
Hat with visor
Long-handled broom with bristles covered with a towel or some bubblewrap
Rowcover or inner tunnels
Some spare plants, back-up plans or a list of fast-growing crops to replace disasters with successes.
PolyPatch tape for fixing holes in the plastic
Gorilla tape for fixing many problems
Pond noodles or other draft-excluding sausages if your doors let air under them
Perhaps some sturdy poles or 2x4s to help support the roof in case of very heavy snow.
Hot chocolate/tea/coffee for when you get back indoors.

Plan D: seed flats in our hoophouse on Oct 16, a late attempt to make up for things that went wrong!
Photo Pam Dawling

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.

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Preparing your hoophouse for fall and winter