2. How To Grow Lettuce From Seed In Flower Pots. This method of growing lettuce indoors is also super easy! First, going to choose a pot for your lettuce, which have to be that big due to the fact that lettuce roots will only reach about six inches when planted into a pot. Survival Gardening - How To Grow Lettuce Indoors Please note: You are currently browsing img small modern garden ideas decor its that is 1713x1171px in size. This image is listed in urban garden ideas category. Survival Gardening How To Grow Lettuce Indoors, 1713x1171 in 394.27 KB.