This is the time of year to start your seeds for salad greens, such as spinach, lettuce, and arugula. Getting a head start indoors will ensure that you will have fresh greens by late March to early April when daytime temperatures are warm enough for growing and nights are still cool and crisp. Once transplanted in the garden in early March, your seedling starts should take off, if your beds have been well prepared.
Lettuce (Lactuca sativa) is the most variable green—coming in lots of shapes, lead densities and colors. Some of the most common and popular types include the upright romaine or cos lettuce (popular in Caesar’s salads), crisphead or iceberg lettuce, and looseleaf types, which include butterhead and oakleaf varieties, among others. Colors vary from bright chartreuse green to deep green, purple and bronze. Speckled varieties also exist, such as the Austrian ‘Forellenschluss’, which essentially translates to “trout-like”. Reliable starter varieties, such as the classic heirloom looseleaf variety ‘Black Seeded Simpson’, super tight-headed romaine ‘Spretnak’, and unusually beautiful French crisphead, ‘Reine Des Glaces’, are all quite easy and delicious.
Spinach and arugula grow under the same conditions as lettuce—requiring cool weather for best growth and flavor. Both are less variable in appearance, but there are quite a few cultivated varieties with special characteristics that set them apart. Spinach may have smooth or savoyed leaves and some varieties are slower to bolt (set flower) in spring than others. The 1925 heirloom ‘Bloomsdale’ has large, savoyed leaves and is slower to bolt than most. I contrast, ‘Corvair’ has large, smooth leaves and is resistant to downy mildew. Some cultivars, such as ‘Baby’s Leaf‘, are recommended for growing “baby spinach”. Arugula cultivars vary somewhat in leaf shape, color and heat. The popular ‘Wasabi’ is an easy-to-grow selection with leaves that truly taste of hot wasabi. The new ‘Dragon’s Tongue’ is a visually pretty, finely cut variant with purple-red venation.
There are a few things to know when growing these greens. To begin with, they must have cool germination temperatures. Lettuce seed, for example, germinates best at temperatures between 70 and 40 degrees F, with those at the higher end sprouting faster. Most other greens do, too. The small, almond-shaped seeds of lettuce also require light to germinate, so be sure not to cover the seed—just gently pat it down and wet its soil completely. Arugula seed is also small and should be surface sown, but spinach seed is larger and can be planted just below the soil’s surface. For planting all these seeds, it is vital to select a quality seed-starting mix with a fine texture, such as Fafard Seed Starting Mix with Resilience. (For more seed-starting tips, click here.)
Before planting, be sure to harden seedlings off, slowly exposing them to outdoor temperatures and sunlight until they are acclimated. Soil should be fortified with a quality organic amendment. I recommend Fafard Garden Manure Blend for greens. Work it in evenly before planting your seedlings. Once seedlings are planted around six to eight inches apart, water them well and apply a light solution of water-soluble, all-purpose fertilizer.
In no time, you should have harvestable greens. In is not uncommon for most greens to take between 45 to 50 days to produce after planting. Harvest depends on the green. Spinach, arugula, and looseleaf lettuce can be harvested leaf by leaf while romaine and crisphead lettuce are harvested whole by the head. The easiest way is to cut the head with a harvest knife from the point where it meets the ground.
It is not uncommon for a few stray greens to begin bolting before they are harvested. If this happens, let them bloom and set seed. After plants have bolted, wait for the seed to mature and dry. Then collect the seeds for planting later in the season when growing conditions are cool once again.