Good growing conditions—including adequate light, moisture, and fertility—bring the seedlings to the next stage: planting out. Lettuce should be planted outdoors after the chance of a hard freeze is past, about four weeks before the average date of the last killing frost. The lettuce roots should be just filling their cells, which typically takes a month or so but will vary with temperature and growing conditions. This pregrown lettuce will be ready to plant in rows or pop into the ground at odd spots, such as between larger vegetable or flower plants that have yet to fill their spaces or where other vegetables have been harvested. The transplants can take some frost but will need covering if temperatures fall below 30°F.

I sow pinches of lettuce seed every couple of weeks from early spring through fall to keep a steady supply of young plants whose leaves are succulent and tasty. The whole process can end up yielding a lot of lettuce, but don’t feel obligated to plant out or even eat every single head you produce. Lettuce seed is relatively cheap, especially when you use only a pinch at a time.

Healthy lettuce loves nitrogen

Lettuce, like other leafy vegetables, grows and tastes best under optimal growing conditions. It likes nitrogen most of all. I maintain fertile, nitrogen-rich soil by applying a 1- to 2-inch-deep layer of compost on top of the ground each autumn where I know my lettuce will be going the following year.

Protect your lettuce from extremes

Once I have lettuce growing consistently through the season, my next technique for year-round lettuce is to protect the planting as necessary for seasonal changes and weather conditions. This includes extreme heat and extreme cold.

Late-winter and early-spring sowings need protection from the cold, so my very first plantings go into the greenhouse. Later-spring plantings, which go outdoors, get protection beneath the cover of my cold frame or from various cloches or row covers, which I use to temporarily cover my garden beds.

Summer plantings are subject to heat and the burning sun, which may cause early bolting. Although young plants are less likely to bolt than older plants during the long, hot days of summer, shading further reduces this possibility. I plant summer transplants in the shade of other plants, such as tomatoes, or beneath trellises on which vines are growing.

When temperatures plummet again in autumn, an additional layer of floating row cover provides a few more degrees of cold protection, keeping lettuce crisp and tender while temperatures drop into the low teens.

The last transplants of the year go back into the greenhouse, completing the cycle. With short days and cool winter temperatures (down to 35°F) in my greenhouse, these transplants grow slowly but fast enough to keep garden-fresh lettuce ready for salad year-round.