One project we're embarking on this year in the Derwood Demo Garden is growing lettuce year-round (or as close as we can get). Lettuce is a perfect crop for spring or fall: quick-growing, tolerant of cool weather, useful. But it often flags, turns bitter and bolts in hot weather, and heavy frosts will kill it.
The solutions to this are:
- Grow in an area that gets more sun in the spring than in the summer - in the shade of a tree is great, or use shade cloth to alter the environment;
- Choose varieties that suit the season;
- Keep well-watered in hot weather;
- Grow under a cold frame or plastic-covered tunnel in the winter.
Our salad tables are shaded by a large maple tree, so that's where we will grow our summer lettuce. We've had success growing well into July before there, but haven't systematically planned to keep going - it should work, though. We'll try a few in the sunnier parts of the garden to see how they do, as well. And we'll get the cold frame out for winter.
We're starting our spring lettuces indoors for transplant.
Summer lettuces will be started directly in the salad table in part, plus we'll start more seedlings indoors. We'll use succession planting to start new plants every couple of weeks. If we are lucky with the weather and our varieties, we should be able to continue this through to fall, when more cold-tolerant lettuces will go in - some in the salad tables and some in the ground to be covered by a cold frame.
You can grow just about any lettuce for spring and fall. Some are particularly cold-tolerant and good for holding over winter. Here's the list of varieties we're trying for summer, all of which are supposed to be heat-tolerant and bolt-resistant.
- Green Star
- New Red Fire
- Summer Bibb
There are lots of other similar varieties out there, which we'll try in subsequent years. This is a growing market niche, for obvious reasons - it's hot out there, and we love our summer salads. We're keeping track of which ones do best for us. If you have had success with summer-grown lettuce varieties, leave a comment - we'd love to hear from you.