Preparing your hoophouse for fall and winter

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

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