Assuming you have the luck of the Irish or a little help from St. Patrick, it's time to plant cool-season vegetables.
Part of the success of growing high-quality vegetables is planting them at the right time. To facilitate this, it helps to divide vegetables into two different categories based on temperature: cool-season vegetables and warm-season vegetables.
In these broad cool and warm classifications, vegetables show differences in their ability to withstand freezing or excessively warm temperatures. The cool-season vegetables are classified as hardy or semihardy; the warm-season are tender or very tender. The deciding criteria are the temperature at which the seeds will germinate and the temperature at which the plant grows best.
Cool-season vegetables can withstand light frosts with minimal damage. This classification is based on the ability of the seeds to germinate at low temperatures and young seedlings that can withstand frost.
Cool-season vegetables germinate at a minimum soil temperature of 40 F, with an optimum temperature of 65 to 75 F. Air temperatures in the same range allow cool-season vegetables to grow well. Cool-season vegetable growth slows down with warm summer temperatures.
Warm-season crops grow best with, well, warm temperatures. They are divided into tender or very tender categories. Warm-season crops stop growing when exposed to cool temperatures and die if temperatures drop below freezing. Warm-season vegetables require a minimum temperature of 55 F and optimum temperatures of 75 to 85 F for best germination.
Cool temperatures are essential for the germination and growth of hardy and semihardy vegetables, but they are also essential for good flavor and texture. If these vegetables grow and mature when it is too hot, they are tough and have a bitter taste.
The hardy vegetables are the first to be planted in the spring, many as soon as you can work your garden soil. Because most soils are drier than normal this year, take advantage of the chance to plant earlier. Do this simple test to see when you can work the soil. Dig a handful of soil from below the soil surface. Squeeze the soil into a tight ball with your hand. Toss it gently into the air. If it comes apart when you catch it, you can till the soil and plant the vegetables.
Two perennial vegetables are in the nurseries right now. Purchase asparagus and rhubarb as bare-root plants or crowns. Because they are hardy, plant them as soon as your soil is dry enough. The bare-root plants are less expensive than potted starts, but plant them before hot weather comes.
Onions are another hardy vegetable. Onion growers in northern Utah are anxious to get their crop into the ground because onions are day-length sensitive. If they are not in the soil early enough, they do not form the large bulbs. Instead, the onions have large leaves and small, poorly formed bulbs. Plant onions from seed or from transplants. Onion sets are usually not going to produce large bulbs.
Lettuce is another hardy vegetable. While our grocery store mentality has conditioned many of us to think only of iceberg lettuce, there are many other wonderful types. In addition to the iceberg head types, there are the bibb or butterhead and the romaine head types. Perhaps the most interesting are the many different types of leaf lettuce.
If your salads are a little boring, look for the new varieties of leaf lettuce in all their variations. Leaves range in color from deep red through pale yellow, and from large, flat leaves to thin, frilly delights. Lettuce is one of the earliest germinating crops, so plant as soon as you can put the seeds into the soil.
Spinach is also an early, hardy crop. Plant it early, because as soon as temperatures start to get hot, spinach bolts or goes to seed. The same is true for Swiss chard. It is so hardy that some Utah gardeners are cutting some from cold frames or from plants they covered with row covers, enjoying the fresh leaves during this unusually warm winter.
Peas are hardy, and some gardeners make planting them on St. Patrick's Day a tradition. Although the plants are hardy, the pea seeds are susceptible to many different fungi in the soil. These attack the seeds and destroy them before they start to grow.
Seeds used to be treated with fungicides to prevent this from happening, but most seeds are no longer treated. If you want to plant peas early and the soil is too wet and cold, you might want to treat the seeds yourself.
Radishes are also hardy and, in fact, the fastest growing of all the hardy crops. Some varieties are ready in as little as three weeks, although cool temperatures will slow their maturity. Avoid planting too many at one time, because they quickly get too large and pithy, and the taste becomes hotter as they get older.
Look for some of the many different types including the round and oblong shapes and the different colors. Radishes are white, red, purple, pink and mixtures of all of the above colors. If you can't decide on which one you would like to grow, choose one of my favorite varieties, "Easter Egg," which gives you several different colors in the same seed packet.
Two other crops are hardy enough to plant now. These are turnips and kohlrabi. If you have serious problems with root maggots, grow the kohlrabi. It has a similar flavor and is far less susceptible to the maggots.
Rounding out the hardy vegetables are the cole crops. These are members of the cabbage family. In addition to cabbages, add broccoli, cauliflower and Brussels sprouts. These need to grow while the temperatures are cool or they become tough and bitter.
Early planting is particularly timely this season because you can grow and harvest many of these crops with little or no supplemental irrigation if you plant them early enough. With an uncertain water situation in many areas, this makes more sense than ever.
Sagers airs on KSL
Listen to Larry Sagers on the KSL Radio "Greenhouse Show" Saturdays from 8 to 11 a.m. The subject this week is pruning roses.
Larry Sagers is the regional horticultural specialist, Utah State University Extension Service, Thanksgiving Point Office.