Want a dizzying variety of tastes, textures, and forms of beauty? Want ’em quickly and in a small space? Welcome to the wonderful world of lettuces. There are hundreds of varieties available, choices that meet every growing need. But they all break down into four main types:
- Leaf lettuces. These lettuces do not form tight heads. No matter how large they get, they are always loose collections of leaves, bound together at the base. Leaf lettuces are the quickest to mature and also the best for cut-and-come-again harvesting — just cut only the outer leaves and the plants will keep making more.
- Butterheads. The heads may be loose or tight, baseball to volleyball size, but they are always composed of leaves that are softer and — if well grown — sweeter than those of other types. Most butterheads are very heat sensitive and produce well only in spring and fall.
- Crispheads. As their name makes clear, crisphead lettuces form tight heads of very crisp, juicy leaves. This is the class to which iceberg belongs, but don’t let that keep you from trying it. Homegrown crispheads are delicious; but they do take longer to grow than other types, and they are the pickiest about good growing conditions.
- Cos. These are the heading luttuces with the tall profile, also known as romaines. Although they eventually come form tight heads, they can be grown as cut-and-come-again, and although they are both crisp and juicy, they are somewhat easier to grow than classic crispheads.
You grow lettuces from seeds, which keep a surprisingly long time. How long seeds remain viable depends not only on the type of seed, but also on how the seed was stored. The combination of warmth and humidity is the biggest enemy. If the temperature and relative humidity add up to less than 100, your seeds will last longer.
When stored under ideal conditions — airtight, in a cold, dark location — lettuce seeds can last up to six years. But as the ideal is seldom met, use this as an estimate, not gospel.
Since lettuce often does poorly in mid-summer heat, it is usually grown as a cool-weather crop: sown in spring and grown through early summer, then sown in late summer and grown through early autumn. But there are many varieties specifically bred to withstand summer conditions, and most catalogs identify them as such.
For best results, try out a few different heat-tolerant selections. All are likely to fare better than spring and fall varieties do in the summertime, but some will probably do quite a bit better than others, depending on the specific conditions in your garden.