Winter lettuce and other salad crops

Salad Mix freshly harvested. Lettuce-free mix!
Photo Pam Dawling

We are feasting on our winter salad mixes now, so I decided to write a post to encourage more people to grow winter salads.

Just how viable this is for you depends on your winter climate zone and your facilities. In the coldest of places with nowhere except your kitchen or a windowsill, you can grow sprouts and microgreens.

To grow sprouts, get some organic seeds, soak them in a jar, then fit a straining lid, which can simply be a piece of fabric held in place over the open mouth of the jar with a strong rubber band, or, if using a Mason jar, the metal ring part of the lid. Drain off the extra water, then set the jar on its side, with the seeds distributed evenly along the side. Rinse and drain twice a day, until the sprouts are the size you want. Here’s a couple of websites.

See How to Grow Sprouts at Home, by Beth, or Growing Sprouts at Home, by The SproutPeople

You don’t need to follow these directions word by word, but if you do, it will work. Other methods can also work. Just be sure to rinse and to drain!

The enthusiastic author of How to Grow Microgreens, Sylvia Fountaine, lays out a 6-step process and provides a video. Microgreens are basically seedlings, with stems and green seed leaves. Sprouts are mostly root and stem, as you may have noticed.

For those wanting to grow microgreens professionally, I recommend Andrew Mefferd’s chapter in his Greenhouse and Hoophouse Grower’s Handbook.  

I wrote about our Fall Lettuce Transition in my post Preparing your Hoophouse for Fall and Winter 9/28/22 – This post includes days to germination of lettuce at various soil temperatures. Here are dates when we sow lettuce for growing in various places (not just our hoophouse).

·        For outdoor lettuce I stop sowing August 29, transplant those 9/22 and expect to harvest them 12/10 – 12/31. I add hoops and thick rowcover when it gets cold to keep it growing.

Buttercrunch Bibb lettuce in December. Photo Kathleen Slattery

·        For winter growing in coldframes, I sow 9/1, 9/3, 9/5, 9/7, 9/9 and transplant 9/25 -10/8. Leaves from those plants can be harvested all winter until we need the cold frames to harden off spring transplants in mid-late February. We cover the coldframes with rowcover when it starts to get cold, then plastic-glazed lids as it gets colder, and quilts for really cold spells. These days we are more likely to direct sow spinach in the frames than transplant lettuce. It’s hardier and faster growing.

·        From September 11-17 we sow lettuce every other day in our outdoor nursery bed, to transplant in our unheated greenhouse (double glass windows, solid north wall, rarely freezes in there). We harvest those lettuces by the leaf all winter until we need to dig out the compost they are growing in to fill our seed flats in early February.

Lettuce growing in our greenhouse in November.
Photo Wren Vile

·        On September 15 and 24 we sow lettuce outdoors in a nursery bed, to transplant in our hoophouse 10/15 and 10/24. Those lettuces will feed us all winter, 11/16-3/1, if we simply harvest the outer leaves, rather than cut the head.

Green Panisse and red Revolution lettuce in our hoophouse in November.
Photo Pam Dawling

·        On October 23 we start sowing lettuce mix in the hoophouse. We sow successions of baby lettuce mix directly in the soil 10/24, 12/31, 2/1, 2/15. The last one, on 15 February, will be 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. We like Fedco’s 2981LO Lettuce Mix OG or Johnny’s Allstar Gourmet Lettuce Mix #2301. For those with challenging growing conditions, both companies offer other specialized selected mixes. 1 oz (28gm) of seed sows about 600 ft, (200m) 

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

·        We sow “filler leaf lettuces” in our hoophouse 10/23, and 11/9, to use for gap filling (replacing casualties). 1/25 is our last date for filling any gaps in the hoophouse beds with lettuce plants. After that, we fill all gaps with spinach plants.

Short rows of filler greens in the north edge bed of our hoophouse in December.
Photo Kathleen Slattery

·        So, we have different “stop-dates” for the different types and locations, but no complete Lettuce Stop-date.

o   8/29 Last date for sowing for outdoor row-covered lettuce

o   9/9 last date for sowing to transplant in coldframes

o   9/21 last date for sowing for planting in an unheated greenhouse.

o   9/24 last date for sowing for planting into a double-layered hoophouse

o   11/9 last date for sowing “filler leaf lettuces”

o   2/15 last date for sowing baby lettuce mix in the hoophouse.

How should people not in central Virginia calculate their own stop dates? Using the same numbers as above for the various types and locations:

  1. ​Figure out how late in the year it’s worth having lettuces outdoors. When does the temperature drop to 20°F (-7°C)? Stop sowing for outdoors 3-4 months before then. (Our 8/29 sowing is harvested by 12/31, but our 8/20 sowing is harvested by 11/25). It’s worth experimenting to find which date works best. Outdoors, I have found that lettuce may survive an occasional dip to 10°F (-12°C) with good rowcover. Consult your Extension Service and the website WeatherSpark.com. Fill in your location and look at pages of useful info about the weather where you are.
  2. Figure when your coldframes get down to say 15°F (-9°C). This might be when the outdoor night-time low is 10°F (-12°C), lower if you have a well-insulated coldframe. We have some old quilts to roll on top of our coldframe on nights below 15°F (-9°C). Perhaps lettuce won’t make it all the way through winter in a coldframe in your climate. If so, be prepared to clear the plants when it gets too cold. Calculate back to figure when to sow – allow 4 months to get full sized lettuces.
  3. Figure when your solar double-paned-glass and masonry wall greenhouse gets down to ° (-9°C), or add a small heater with a thermostat to keep it warmer than that. Calculate back to the sowing date, allowing for the fact that plants grow quicker in a greenhouse than outdoors or in coldframes. Maybe allow 3 months.

    Our greenhouse with young lettuce transplants in early October.
    Photo Bridget Aleshire
  4. As far as daylight goes, on 9/24 everyone everywhere is pretty much getting the same amount wherever we live. With a hoophouse, the goal is to grow plants to harvestable size by the time you no longer have lettuce from outdoors (refer to #1). It probably only takes 2 months to grow a lettuce big enough for leaf harvest in a double layer hoophouse. Just be sure not to over-harvest in the winter. We have had lettuce survive a double layer hoophouse temperature of 10.4°F (-12°C) without any rowcover (sometimes called an inner tunnel), and -2.2°F (-19°C) with.
  5. At this point calculations switch to what happens after the Winter Solstice. When do you plan to start harvesting your first outdoor lettuce again? Aim for a two-week overlap with both hoophouse and outdoor lettuce available in the spring. Work back from your hoophouse harvest end date to find the last worthwhile sowing date for filler lettuces. Because lettuce bolts easily when it gets warm in spring, play it cautious. We plan to start outdoors 4/15. We stop transplanting lettuce in the hoophouse 1/25, 2 1/2 months before then. Sowing filler lettuce too late is not really a problem – you can cut it as baby lettuce. But avoid transplanting it just to have it bolt.
  6. If your climate is cold, or you don’t mind only getting one or two cuts from baby lettuce mix, you can carry on sowing it until the soil temperature reaches 86°F/30°C (max temp for lettuce germination). If it is warm, do be sure to water often, so the lettuce doesn’t turn bitter. Otherwise look to you first outdoor lettuce and clear the baby mix when the outdoor crop is ready.
Beautiful baby lettuce mix in our hoophouse in February.
Photo Wren Vile

See my post Lettuce All Year in a Changing Climate 8/31/21. It includes links to all my Lettuce of the Month series, and includes my slideshow Lettuce Year Round and our 2022 Lettuce Varieties List, to help you choose varieties we recommend for different times of year.

For ideas on mixing various crops in winter salads, see Making Salad Mix 10/31/17 and Fast Growing Vegetables 3/24/20. Winter salad mix is also known as mesclun or spring mix (even though we are growing it in the winter). Spinach and many brassicas grow faster than lettuce in cold weather, and make delicious salads.

Bulls Blood Beet leaves
Photo Bridget Aleshire

Also, check my Asian Greens of the Month posts. This post from April 2018, includes at the end links to each of the series. Many Asian Greens make great salad crops. The frilly mustards featured in this post are a good example.

For information on the temperatures that many crops will die at from cold, see Winter Kill Temperatures 2021. I was updating this list each spring. 2022 seems to have slipped by. I don’t think I had any new information, as the winter wasn’t extreme (although we had a long and memorable power outage!).

 

Preparing for Spring Transplants

Seed flats in the greenhouse in early spring. See the large lettuces growing in the beds, between flats of seedlings balanced on the bed walls.
Photo Kathryn Simmons

Preparing for Spring Transplants

We have winter to enjoy/experience/endure before we start spring seedlings, but there are some steps you can take to make spring start-up easier and more successful. Of course, there is the usual list of tidying your workspace, preparing to order seeds and repairing tools.

Replacement tool handles

House Handle Company   Telephone: (800) 260-6455 has a wide selection of good quality wood handles online. They specialize in hickory, white oak and ash. Be careful making your selection, and get the handle that’s just right for the tool you are repairing. You can see a lot of their handles in our photos. During the winter we usually have a “Santa’s workshop” day when we repair tools.

There are YouTube videos showing how to make sturdy repairs. Just be sure to shape the handle for a good fit before drilling any holes for rivets. And learn how to make rivets from large nails if none are supplied with your replacement handle. Sharp edges on poking-out badly finished rivets, or nuts and bolts can cause injuries. Sweat we might need. Blood and tears we can do without.

Screening a large pile of compost for the greenhouse beds. Photo Wren Vile

Seed Compost

Today I’m thinking about seed and potting compost.

We use 100% home-made compost for sowing seeds, and for potting-up transplants. We don’t mix in any other ingredients. Our seed compost is our regular good-quality compost, screened to remove large particles, and matured over the winter into a very mellow combination of nutrients and micro-organisms. We make great compost and it grows big strong plants.

We screen a big pile of compost in September, and fill the cinder-block beds in our solar-heated greenhouse. See this post: Screening compost to make our own seed compost for spring. If you are making your own screens, you can use hardware cloth (rat-wire), or do as reader Jim Poole suggested and try stucco lathing instead. “It is quite a bit sturdier. (But watch out for the cut ends when installing it- it can give you a nasty gash.)”

We need a lot of compost, but the idea works fine on a smaller scale too. Find an indoor place near where you will use the compost in the spring, and some tubs to put the screened compost into. If you want the full tub to be on a bench in spring, put the empty one on the bench and screen into it! If you want to grow lettuces in the compost, put the tubs near a window.

Just storing the compost inside over the winter will mean you are not dealing with frozen stuff when you want to sow. But better yet, see Starting Seedlings and Preparing for spring, sowing seeds, for more about how we grow lettuces in the stored compost over the winter in our greenhouse, then use that compost in spring for seedlings.

Greenhouse beds filled with screened compost.
Photo Wren Vile
Lettuce growing in screened home-made compost in our greenhouse in November.
Photo Wren Vile

We transplant lettuce at 10″ spacing into the beds in mid-September or early October. By harvesting only the outer leaves, we keep those lettuces alive and growing all winter to give us salad from November to February. Because we water the lettuces, the compost organisms stay alive and active. If you don’t grow a crop overwinter, water the compost from time to time to keep it slightly damp.

This system provides us with a large quantity of mellow screened compost for seed flats, indoors and not frozen. The micro-organisms have had plenty of time to colonize the compost, so it is full of life. In spring, as we need space in the greenhouse, we pull the lettuce. We can then scoop out the compost to fill the flats for seedlings.

Aphids

The only issue we sometimes have is aphids in early spring. This winter we are experimenting with some plants we hope will flower in early spring and attract beneficial insects who also eat aphids. I’ll report on this project when we see the results.

Here’s what we currently do to deal with early spring greenhouse aphids:

  1. jet the plants with water to project the aphids into outer space (OK I’m exaggerating),
  2. gather up lady bugs, or
  3. if numbers of aphids are really high, we use a soap spray.

We start our first seedlings in mid-January, although we only sow a few things the first week (cabbage and lettuce for outdoors and tomatoes for our hoophouse), and harvesting just one or two lettuces would provide enough compost for those few flats.

Lettuce transplants in soil blocks. Photo Pam Dawling

Soil blocks

We used to make soil blocks for our more delicate transplants (melons, early cucumbers and squash) because there is no transplant shock when you plant them out. We even used them for lettuces at one time. We developed a very simple recipe, which we seem to have lost, but it was something like 1.5 parts by volume of our home-made compost, 1 part of soaked coconut coir and as much water as needed to make a wet slumpy, but not soupy, mix.

I use coir rather than peat moss, because I believe the extraction rate of peat moss is not sustainable, and as a carbon sink, it’s better to leave it in the ground. Coir is a tropical food by-product. I’m sure it’s better returned to the soil where the coconuts are grown.

The mix is compressed into a special block-maker, which is then scraped across an edge of the container of mix, to create a flat base, and then the block is ejected using the spring-loaded handle into a tray or open flat. We line our flats with a sheet of plastic to reduce drying out. It’s important to dunk the block maker in water between fillings to wash off the old remnants and enable the new blocks to slip out smoothly.

The blocks are surprisingly stable – they can be picked up and moved, like brownies. Or you can move several at once on a kitchen spatula. As the plants grow, the roots get air-pruned. Even if you pack the blocks shoulder to shoulder in the tray, the roots from one block do not grow into the others. There is no root damage at all when the complete block is transplanted. Do make sure you press the surrounding soil down and inwards to make good contact with the block.

Okra seedlings in a Winstrip tray in the greenhouse. Note the vented cell sides.
Photo Kathryn Simmons

Winstrip trays

More recently we have come to love Winstrip trays, very durable plug flats with cubic cells that are vented down the sides, so the plants get air-pruned. The bottoms of the cells have finger-sized holes so you can easily pop a full-grown transplant out of the tray. The Winstrip 50 cell tray has cells almost the size of soil blocks. These flats have all the advantages of soil blocks except price. They are expensive. We got ours used. Winstrips have two additional advantages: they are much quicker to use than soil blocks, and they work with all-compost. We don’t add any coir. One less input to buy. I haven’t calculated how many plugs-worth of coir pay for one Winstrip tray. . .

See this post on using Winstrip trays and transplanting plugs from them

For more about soil blocks, and Winstrip and other plug flats, see my book Sustainable Market Farming