You can plant lettuce seed in between onion sets or, all alone, as early as you can work the soil. By the time the onions are ready to be pulled, the lettuce will have already been in the salad bowl! Lettuce likes a bit of shade to keep it from turning bitter. This extends their season.
Onions and lettuce are companions in the garden.
Lettuce seed is tiny; it is easy to waste them by planting too many. Later you have to thin them all out, so plant only 3-4 per selected site.
Companions to plant together are radishes, carrots, beets, chard, mustard, kale, and onions.
You can plant them all very early as well. The longer, cool nights gets them off to a good start. The seeds will germinate in 7 – 10 days.
Seeds keep well for 2-3 years, so you may try planting 4 or 5 varieties to find ones you really like. ‘Ashley’, a red leaf, and ‘Vivian Romaine’ are two of my favorites. You can plant every two weeks for an extended harvest. Soon, you will enjoy the first greens of the season.