Both of the lettuce plants in this photo were started in an AeroGarden Deluxe indoor planter about the same time. They were grown from the same packet of seeds.
The one on the left was put out into the garden soil as soon as it had secondary leaves. The one on the right was left inside for a couple weeks longer.
Clearly being kept indoors in the AeroGarden gave the second plant a distinct advantage.
This is pelleted Green Forest Cos from Johnny's Selected Seeds. Romaine is my favorite lettuce to grow. It is a heat tolerant cut-and-come-again green that can be used for salads or wraps.
I tried a packet of one of their red Cos varieties, but for some reason it would not sprout for me in the AeroGarden. I tried four different plantings, then returned the packet and they replaced it with this tried and true variety.
I am a big fan of pelleted seeds, although it is said that their shelf life is not as long as that of regular seeds.
Whenever I see pelleted seeds, I think of the ancient technique of preserving seeds in dried balls of clay and compost. There are quite a few posts online about seed balls, but so far this one is my favorite: