Filling Up Spring with Garden Lettuce

15 April 2011, written by Barbara Pleasant

Fast-growing and vibrantly beautiful, garden lettuce begs to be planted repeatedly for as long as cool spring weather lasts. Gardeners can grow a huge range of colourful varieties that are seldom seen in stores, but we do have limitations. Two types of lettuce – big icebergs and tall romaines – can be difficult to grow because hot weather arrives before they reach perfection.

Yet good garden lettuce does not lack crunch. Two English heirloom varieties that should be on every gardener’s life list include ‘Little Gem’, a miniature Romaine with a cute, upright growth habit, and ‘Tom Thumb,’ a baby butterhead that has been pleasing gardeners for more than 150 years. Many Americans would add ‘Buttercrunch’ to this list, because like Tom Thumb, ‘Buttercrunch’ delivers the perfect marriage of crisp ribs and buttery leaves in a compact, nutritious package.

Gardeners often do very well with leaf lettuces because of their heat tolerance and resistance to bolting. Leaf lettuce varieties are so varied that you could garden for a lifetime and still not try all of them. One of the best ways to explore leaf lettuce (sometimes called non-hearting lettuce) is to grow mixtures that include ‘Salad Bowl’ and contrasting varieties like ‘Red Oakleaf’ or ‘Red Sails’; the actual varieties are usually listed on the packet. When properly handled, lettuce seed mixtures intended to be grown as baby leaf lettuce can produce a beautiful tapestry of salad-worthy greens. Compared to other types of lettuce, leaf lettuce is also best for use in companion plantings near broccoli, tomatoes, or other tall vegetables.

Thinning Lettuce

Regardless of the types of lettuce you grow, thinning lettuce seedlings is a task that must be done again and again. If you think of lettuce leaves as solar collectors, your job is simple – keep the plants’ "solar panels" from overlapping, thus depriving their neighbors of light. Thinning garden lettuce is more or less continuous because the plants grow so fast, sometimes doubling in size after a soaking spring rain.

I begin eating my lettuce thinnings when the leaves get big enough to make cleaning them worthwhile, but while they are tiny I often lift and move seedlings as I thin. My method is simple: I use a spoon to scoop up a seedling with the soil still packed around its roots, slip it into a prepared spot, and water well. I’ve become particularly prone to transplanting excess lettuce seedlings to the open spaces between upright onions, where they do a good job of suppressing weeds.

Lettuce seedlings that are left to grow too close become spindly things that bolt early, probably due to extreme competition for nutrients, moisture and light. In comparison, thinning lettuce every few days so that the plants enjoy steady, exuberant growth will give you bigger plants that hold in the garden until hot weather comes along to spoil to party. Best of all, proper spacing and regular water will help your leaf lettuces develop dense, frilly hearts for early summer salads.

Growing Just Enough Lettuce

There is no way to preserve bumper crops of lettuce, so several small sowings work better than one large one. In my climate I can manage three sowings, three weeks apart in spring, and then I stop planting lettuce until nights cool down in the fall. If you’re tracking time and space closely in a square foot garden, it’s worth noting that transplanting lettuce seedlings typically sets them back about a week.

Oak leaf lettuce is easy to grow and perfect for salads of all kinds

Garden lettuce is harvested four different ways – by thinning, by picking individual leaves, by cutting back the plants, or by pulling up entire plants. I occasionally pick lettuce leaves one by one to bring colour or texture to a salad, but I only cut back lettuce when growing it indoors in late winter. Both of these methods hinder the plants’ progress into a glorious rosette of ruffled leaves clustered around a sweet, pale heart. In my opinion, it’s best to let plants keep most of their leaves.

In its prime, garden lettuce is sometimes said to be at the teenager stage, because botanically the plant is ready to shift from its juvenile, vegetative stage to reproductive mode (what we call bolting). The lengthening days and warm temperatures of early summer will encourage all types of lettuce to stop growing leaves and start growing flowering parts, so it’s the natural way of things for garden lettuce to be a short-lived pleasure. Fortunately, when the soil cools down in late summer and the second salad season begins, I can put leftover lettuce seeds to good use.

By Barbara Pleasant