Category Archives: Garden Advice

Saving Lettuce Seed

We’ve been trying to grow and offer seed for Cosmo lettuce. But we have only a little bit of experience with saving lettuce seed on our own farm, so it’s challenging to get a good seed crop of a large enough size.

We let the lettuce head up, then bolt, becoming too bitter to eat, then flower, and finally make seed. (Lettuce plants become a lot bigger when they bolt and flower, so before they bolted we made more room by harvesting every other head for eating.)

Although it’s possible to save lettuce seed outside, even in our wet climate, growing it in our high tunnel keeps the rain off of the seedheads. This greatly increases our chances of getting a good germination rate and being able to sell the seed. We’ve put up a rope around the bed, tied at waist height to six posts, so that the lettuce stalks can lean on it and so that the seedheads won’t lie on the moist ground. Nonetheless, our first harvest looked terribly disappointing.

It’s been a wet spring, and this harvest came after a period of much rain and humidity. I thought we had a crop failure – too little seed to be worth the time it would take to separate it from the chaff. I almost gave up. I moved lettuce seed harvesting down on my list of priorities. But the next harvest, after a couple days of dry weather, gave me a pleasant surprise.

This time, when I shook and rubbed the seedheads over my tray, a significant amount of mature-looking seed fell out along with the chaff. However, it seems some of the seedheads dried up before producing good seed. Shaking old, dry seedheads still basically just gave me chaff, not seeds. A day later, there was rain in the forecast, so I collected a small, early harvest.

I was quite surprised that I got so little chaff and so much seed. Of course, even this seed will need to be winnowed and screened to clean off the chaff. Then its germination will need to be tested before we’ll know if we have enough good seed to list this variety.

For more on how to save seeds, see our Seed-Saving for Home Use handout. Later this year I’ll post more information on how to clean seed by winnowing with a box fan.

Guest Blog Post: Starting Seedlings

Our neighbor Pam Dawling, a contributing writer at Growing for Market, has just released her first book: Sustainable Market Farming: Intensive Vegetable Production on a Few Acres. Pam has been gardening here in the Southeast for many years, and we’re delighted to have this resource, with so much wisdom relevant to our bio-region. We’ve asked Pam to contribute to our blog, and we hope you’ll enjoy reading about her gardens. Pam blogs at sustainablemarketfarming.com/news.


Starting Seedlings, by Pam Dawling

We’ve been starting seedlings since late January, and the greenhouse is filling up with flats of lettuce, cabbage, kohlrabi, spinach, scallions, and broccoli. We’re eating our way through the lettuces that grew overwinter in the compost in the block-work greenhouse beds, and shoveling out the compost to fill our flats. All our seedlings are grown in 100% home-made compost. We screen compost to fill the beds in September and transplant lettuce there in October. When we need the compost for the seedlings, it has mellowed nicely and has plenty of worms. This beats buying in bags of compost, or chipping lumps off a heap of frozen compost outdoors in January!

Greenhouse interior with spring seedlings. Photo: Kathryn Simmons

Our greenhouse has a masonry north wall and a patio-door south wall. It has no heating apart from the sun (this is Zone 7). This space is warm enough and just big enough for all our seedlings once they have emerged. For growing-on the very early tomatoes and peppers, destined for our hoophouse, we use an electric heat mat and a plastic low tunnel in one corner of the greenhouse.

Many seeds benefit from some heat during germination and are then moved into slightly less warm conditions to continue growing. This means it’s possible to heat a relatively small space just to germinate the seeds in. We use two broken refrigerators as insulated cabinets, with extra shelves added. A single incandescent lightbulb in each supplies both the light and the heat (we change the wattage depending on what temperature we’re aiming for). Some people construct an insulated cabinet from scratch, with fluorescent lights suspended above the flats.

The Twin Oaks greenhouse and cold frames. Photo: Kathryn Simmons

We use traditional coldframes for“hardening-off”our plants (helping them adjust to cooler, brighter, breezier conditions). They are rectangles of dry-stacked cinder blocks, with lids of woodframed fiberglass. Having heavy flats of plants at ground level is less than ideal for anyone over thirty-five! Shade houses and single-layer poly hoop structures with ventable sidewalls and benches for the flats are a nicer option. Some growers report that some pests are less trouble when flats are up on benches. Others say flats on the ground produce better quality plants. According to the nighttime temperatures, we cover the coldframes with rowcover for 32°F–38°F (0°–3°C), add the lids for 15°F–32°F (–9°C–0°C) and roll quilts on top if it might go below 15°F (–9°C).

Pepper transplants in pots. Photo: Kathryn Simmons

For brassicas, lettuce and our paste tomatoes (a big planting), we use open flats — simple wooden boxes. The transplant flat size is 12" × 24" × 4" deep (30 × 60 × 10 cm). It holds 40 plants, “spotted” or pricked out in a hexagonal pattern, using a dibble board. For sowing, we use shallower 3" (7.5 cm) flats. Usually we sow four rows lengthwise in each seedling flat. We reckon we can get about six transplant flats from each seedling flat. This allows for throwing out any wimpy seedlings, and lets us start a higher number of plants in a smaller space.

Because we transplant by hand, and because we hate to throw plastic away (or spend money when we don’t need to), we use a range of plastic plant containers. For crops where we are growing only a small number of plants of each variety, we use six- or nine-packs, or a plug flat divided into smaller units.

Okra seedlings. Photo: Kathryn Simmons

The first crops sown are not necessarily the first ones planted out. Our spinach gets sown Jan 24 and transplanted out 4 weeks later. The early tomatoes get planted in the hoophouse at 6 weeks of age (slower-growing peppers go in at 7.5 weeks with rowcover at the ready!). Lettuce goes outdoors after 6.5 weeks, cabbage after 7.5 weeks, cipollini mini-onions after 8 weeks. These are early season timings and as the days warm up and get longer, seedlings grow more quickly. Being a few days later sowing something in early spring makes little difference, as later sowings can catch up by growing faster in the warmer weather.

If the spring is cold and late, you may find your greenhouse packed to the gills with flats you don’t want to take outside. We try to put the faster-maturing crops near the doors and keep the open flats, which will need spotting-out, near the accessible north side.

But let’s not complain about the bounty of so many plants! Spring is an exciting time of year, full of new growth and new potential. Working in the greenhouse with tiny plants on a sunny day when it’s cold outside is a special treat.

Take a Chance on Late Fall Plantings

Article by Ira Wallace, with Lisa Dermer

seedlings nestled into a cold frameCold nights let us know fall is really here, along with the certainty that a killing frost will arrive any day. We’re enjoying bushels of broccoli along with the last outdoor beans, cucumbers, peppers and tomatoes. Beds of greens promise frost-touched sweetness for months to come.

For those who still haven’t made fall sowings of winter greens, it may not be too late. Last year we sowed greens under quickly put together cold frames on November 9, thinking they
would overwinter and be ready for early spring harvest. To our surprise, we were harvesting baby greens from those frames in late December and occasionally throughout the rest of winter. And when the weather warmed up in February, those plants took off well ahead of spring-sown greens.

My fastest growing fall-sown greens were arugula, cress, tatsoi, and kale. Baby lettuce seedlings transplanted from a crowded bed in the garden took off and grew quickly under row cover supported by hoops. We even harvested a last round of radishes from that November planting.

It’s best to avoid unrealistic expectations: last winter was unusually mild, and direct sown plantings made this late in the year may not reach harvestable size until early spring. Transplanting seedlings under protection in late fall gives a better guarantee of winter harvests. We’re transplanting crowded seedlings from the outdoor garden into cold frames or under row cover. A circle of gardening friends is also a great resource for extra fall seedlings, ready to be nestled into their cozy winter homes.

I hope you’ll take a chance on late fall sowings or transplants. Fresh winter harvesrts are one of the most important steps we can take towards food independence.