From The Urban Homestead by Kelly Coyne and Eric Knutzen:
This is a good first project for a beginning farmer. Lettuce is easy to grow, and tastes so much better homegrown than from a bag. Better still, it is always fresh when you want it, instead of rotting in crisper drawer (sic).
It is easiest to grow lettuce in cool (but not freezing) weather. Lettuce is not a sun worshiper. In climates with freezing winters, you should plant lettuce in the early spring. In warm climates you can plant it in the fall as soon as the summer heat dies down, or any time over the winter.
You need one packet of mixed lettuce seeds (also called salad blend or mesclun mix) from your neighborhood nursery. There are many variations on this theme, but basically a mesclun mix contains seeds of several different lettuces and salad herbs. If you can’t find any such thing, you can buy a few different types of lettuce to mix up yourself. Just be sure you buy loose leaf lettuce, not the ball-shaped Iceberg kind.
The next thing you will need is somewhere to plant your lettuce. The best choice would be a self-watering container of the storage tub size. Failing this, any sort of big pot or found vessel would do, as long as that pot has a hole in the bottom of it for drainage. You can even use something permeable, like a basket, if you line it with a plastic garbage bag. Be sure to poke holes in the bottom of the bag for drainage. This general growing technique is suitable for garden beds, too.
If you have a regular pot, put a layer of rocks, or something similarly impermeable, at the bottom of the pot. This will keep the drainage hole(s) from becoming clogged with soil. Fill your pot or self-watering container with potting soil. Not regular garden soil. Add a handful of dry organic fertilizer or worm castings to the pot. If you are using a self-watering container (SWC), leave the fertilizer until later.
– Before you sow your seeds, make sure you’ve set a little bit of soil aside. You need just enough to cover your seeded area with a light sprinkle of soil.
– Level out your soil and water deeply. Check the pot for good drainage. You don’t want your seeds to go swimming.
– Open your seed packet and sprinkle you (sic) seeds evenly over the surface of the soil. Do not make rows or poke holes or worry about spacing. Be free – you’re sowing seed, man. Just let it fall where it wants. Shoot for a coverage rate that leaves the individual seeds about a finger’s width apart, but really, it doesn’t matter much if some spots are thicker than others.
– Sprinkle your reserved soil over your seeds in a very thin layer – 1/4″ or less. It’s okay if some seeds are not covered.
– Water again, lightly this time, with a watering can or a hose on the gentle shower or mist setting, or even with many pumps of a spray bottle. The idea is just to secure the seeds and their covering, since you’ve already watered the pot thoroughly (sic)
– Keep your seeds moist until they sprout, this might take a few days or a couple of weeks, depending on the seeds. The seed pack will tell you what to expect. We use a spray bottle to mist the soil, so that we don’t disturb the seeds with big sloshes of water.
I’ve probably already quoted more than the publisher would prefer, so I’ll paraphrase from here on out. When the plants have their true leaves (as opposed to those generic-looking seedling leaves) and are about 2 or 3 inches tall, start thinning the bed and harvesting the baby greens. Coyne and Knutzen call this “eating your way to equilibrium.” You don’t want to see a lot of bare soil between the plants, but you don’t want them crowding each other, either. The bed should be a nice, comfortable carpet of green with a little space between each plant. When you thin, don’t pull each plant up by the roots – just pinch it off at the stem. Pulling up the roots may disturb the other plants, and dying roots are a great source of food for beneficial soil life.
Eventually, you’ll eat your way to a few full-sized plants (each one approximately the size of a soup bowl). Again, they shouldn’t be too far from each other, but air should be able to circulate between the outermost leaves. From here on out, only harvest the outer leaves until the lettuces bolt (send up flowering seed stalks). Bolting signals the end of the plants’ life cycles. You can either harvest them immediately, before the leaves get tough and bitter, and use the space for something else – or you can let them die, collect the seeds for next season, and use the leaves for compost and mulch.
Food, not lawns!