Lettuce is very healthy and low in calories. That is first vegetable available in markets in the spring. Lettuce which you can buy on the market is usually treated with a number of chemicals. To avoid eating unhealthy food and to keep yourself and your family safe, you should think of growing your own vegetables. Of course, what you need is some space in your garden, but if you don’t have one, and all you have is a balcony, then flower pots will be just enough.
One thing probably important to know is, there is lettuce for spring, for summer, for autumn and for winter. Those are different types because all can not stand same temperatures. If you grow spring salad during summer, it will simply grow up high and then simply blossom and give seed, so there wouldn't be anything to eat.
Lettuce for spring is easy to grow if you plan to do it outdoors and not in the greenhouse. Growing outdoors is what I recommend to all beginners. For outdoors and indoors growing of lettuce, time to sow is same and that is end of August. Prepare soil well, make rows and because this seed is very small I have one trick with plastic cup where on bottom should be opened one hole slightly bigger than size of salad seed. That way as u move cup above row and slightly shake it, seed coming out slowly one by one, which then allows you to get nice space between them for proper growth. Between rows should be 25 cm distance, to allow you using tools to clean up grass and give some air to soil while lettuce growing.
First days in October would be right time to transplant lettuce to where you want it to be. For planting lettuce you need some tool for making holes, and make sure that distance between holes is 25 cm, and same distance between rows. Don't forget to leave paths for walking, otherwise when lettuce spreads in spring, you won't be able to get between to cut those bigger.
If you decided to try greenhouse growing, then there are many ways but this is simple one. Transplant lettuce under already set greenhouses which yet not covered with plastic.
Then in January, after holidays are over, cover greenhouse, make sure to let air in every morning and to keep it open on sunny days. When sun warms greenhouse temperature grows and plants need some fresh air getting inside. When soil gets dry enough, then break crust between lettuce rows to give some air to soil. Within few days you will notice sudden growth. To speed up lettuce growth I recommend agro textile which protects lettuce from low temperatures at night.
If you want to continue growing lettuce next year with your own seed, then leave 1-2 lettuce and don't cut them but let them grow. They will give seed which can be used for next year. Lettuce seed will be very sticky because of juices it produces and seed should be washed in a sieve, carefully, and right away placed on a windy place to dry. When seed is completely dry, get some nice and clean jar and store seed there until next year.