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 design challenge ten urban balcony garden ideas urban that is 614x345px in size. This image is listed in urban garden ideas category. Survival Gardening How To Grow Lettuce Indoors, 614x345 in 216.63 KB.