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Friday, March 1, 2024

Starting lettuce from seed...

Red Iceberg Lettuce - a summer rose!
 Starting lettuce from seed...(and cabbage, broccoli, kale and other cool weather-loving crops).
 
Note: Though this was originally written and posted in 2011, and some of our practices have shifted (for example we no longer use rabbit manure - or any animal by-products - in our garden or soil-mix - LINK: Making Your Own "Veganic" Potting Soil in Your Greenhouse Paths - Using Worms ) - the core of the information is still accurate and useful so we have republished without editing...This post gives generic information for starting cool-weather crops (lettuce, cabbage, broccoli, kale etc) from seed.
 
Here in the Pacific NW, we start our lettuce seed in a greenhouse in late February and then transplant the starts out in April or May when conditions allow. We're vegetarians and end up with a lot of those white, plastic, square tofu containers. We've found they make great tubs to start small seedlings. We drill holes in the bottom for drainage, fill with a good potting mix (using the bottom of another tofu tub to pack the soil firmly and make a flat surface for the seeds).

After misting the soil so it is good and damp, we sprinkle the lettuce seeds with our finger-tips trying to have a 100 or so seeds per tofu tub.  Lastly we gently sprinkle a thin lay of cover soil over the seeds and lightly mist to settle the seeds. They must be kept moist but not overly wet or the seeds and starts may rot. Lettuce seed germinates best in a cool soil so don't put it on a heat mat or under a lamp to get it to germinate.

Lettuce seedlings in a tofu container. Using a pen to make holes for transplants.
When the seedlings are about 1/2" - 1" (2 cm) high, they are ready for transplanting. We put ours in regular or "jumbo" six-packs. We use a basic, organic potting soil and add our own fertilizer. To each wheelbarrow of soil we add about two cups of all-purpose organic fertilizer and about a half-gallon of sifted rabbit manure . When germinating tiny seeds (such as lettuce), we sift the soil before adding amendments so the seedlings don't have to push past un-composted bits of bark or wood-chips in the soil. For transplanting, we don't bother to sift the soil.

Transplanting seedlings
For the Sharing Gardens, where we might grow 1,000 or more lettuce plants per season, transplanting is done in large batches. Being systematic in the nursery will save you time and materials and you will have much better results. Have labels ready so you keep track of the varieties you are transplanting. Fill a flat of six-packs and mist it with water and soak the seedlings too. Wet soil is less shocking to transplanted roots than dry. Cupping your hand over the whole tofu-tub of seedlings, flip it over and tap the bottom, catching the whole clump of soil and seedlings in your hand. Gently flip it back over and place it on a tray to catch the loose soil as it drops off.

Seedlings "hardening-off".
Using your finger. a stick or some other object, make a generous hole in each of the cells of the six-packs. Pull off a clump of seedlings and, holding them by their leaves, tease apart a single plant with its roots. On a cool, overcast day you can lay a large number of the seedlings alongside their holes before dropping them in and squeezing the soil around them. If the day is hot or the sun is strong, work in smaller batches so the seedlings don't get shocked. It is very important that all the roots go down into the soil and are covered. If they stick out from the surface, this is called 'J-rooting' and  will often kill the plants as they dry out too easily. This is why you want to dig a generously-sized hole so the rootlets don't catch on the sides as you lower them in. After pressing the soil in around each seedling, water them in gently to settle the soil. Label the tray and move onto the next.

Transplanting peas and lettuce
Depending on warmth and sunlight, and the size of the six-packs you use, your lettuce will be ready to plant in the soil in six to ten weeks. If you stagger your plantings it will mean your lettuce doesn't all come ripe at once. Ideally you wait until the root ball has filled the six-pack cell enough to hold the soil as you pop it out, without being totally root-bound (roots coming through the bottom of the six-pack). A week or two before you transplant into your garden, bring the starts outside and begin "hardening them off". Put them where they will get plenty of sun but not too much wind. They will withstand a light frost but if it is going to get very cold, or doesn't warm up in the day, bring them back into the greenhouse till conditions improve. During this hardening-off period, prepare garden beds so they are ready to receive transplants. In our "deep-mulch/minimal till" gardens, we pull a row of mulch over to the adjacent path (with a pitchfork) and, with a trowel dig a small hole just the size of the lettuce's root-ball. This leaves worm holes intact and lettuce seems to thrive without any roto-tilling needed.

Several weeks after transplanting. Picking individual lettuce leaves for salad.
Here in our area, slugs can be a real problem in the spring. Follow this link for ideas on how to re-use milk cartons or soy-milk containers to thwart off their feasting. Re-Purposing Things We don't find that additional fertilizing is necessary for lettuce plants. They receive enough nutrients from the soil. We hold off on mulching them because we want the sun to warm up and dry out the soil and mulch provides habitat for the slugs. Sometimes, after the lettuce is well established and the soil is warmed up, we mulch with a few inches of grass clippings around our plants. Let the clippings dry out for a few days on a tarp or in a bin. Fresh clippings, if piled thickly, can heat up considerably and burn your plants.

Chris Burns with beautiful lettuce harvest! 2011
We plant our lettuce spaced about 6" - 8" (12 - 15 cm) apart. We harvest them intermittently giving the remaining lettuce room to grow. In the early stages, before the heads are fully formed, we harvest one to three leaves off each plant, rather than clipping whole heads. As the heads become full size we harvest by cutting them off at the root with a paring knife, leaving the roots in the ground to feed the worms.

Fall Crops: Give yourself 45 - 60 days (before hard freezing) to grow your fall crops of lettuce. You can assist your lettuce in germinating if you begin the process in a shaded area so the soil isn't too warm. Once seedlings come up, they will need sunlight to grow but do this outside of the greenhouse so they don't get too hot. Heat triggers the plants to "bolt" (go to seed) even when the plants are very young.

Favorite varieties: Everyone who eats out of our gardens seems to prefer green lettuce to red, or at least to have some green to mix in with the red. (This even includes the bugs and sparrows who seem to devour the green lettuce much more voraciously!) Our recipients also seem to prefer head lettuce to the "leaf" lettuce. We don't know why this is (maybe just habit...) but we take this into consideration when we plant out our gardens. There are hundreds of varieties of lettuce to choose from. The most popular ones we grew this year were:

Slo-bolt (Black-seeded Simpson)
Chartwell's Romaine
Green and Red Iceberg (home-grown Iceberg lettuce is much more nutritious than store-bought).
Four Seasons (a red Romaine-type lettuce)

LINK: How to Save Your Own Lettuce Seed


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