Planting a cool season vegetable garden is a great way to start the spring gardening season. First, prepare the soil as soon as it can be worked. It is workable when a handful of firm soil crumbles in your hand when gently pressed. Apply recommended nutrients at this time according to soil test results. Phosphorus is especially important, as cool soils tend to limit its’ availability to early planted vegetables.
Cool-season vegetables should be planted in early April in northern Missouri. Root crops that can be planted now include radishes, beets, carrots, and parsnips. These require well-drained soil with plenty of organic matter. Plants should be thinned to the correct spacing when plants are two to three inches tall.
Early leafy vegetables that should be planted now include broccoli, cauliflower, kohlrabi, spinach,lettuce, cabbage, mustard greens,collards, Swiss chard, and Brussel sprouts. Plant by direct seeding or by using transplants. Other cool-season vegetables to plant now include onions, potatoes, and peas. Cool-season vegetables are able to withstand a light frost and temperatures near 28 degrees Fahrenheit. Be prepared to cover them if temperatures fall into the mid-20s.
Plant perennial vegetables like asparagus and rhubarb at the edge of a garden as these can be long-lived plants. Purchase one-year-old asparagus crowns or seedlings from a garden center or local nursery or through mail order catalogs. Asparagus plants are male or female. The male plants produce larger spears. Many of the Jersey all-male varieties perform well in Missouri, including ‘Jersey Giant,’ ‘Jersey Knight’ and ‘Jersey Supreme.’ Plant asparagus in a sunny, well-drained location. Add several inches of aged compost or organic matter to the planting bed. The optimal pH for asparagus is 6.5 to 7.0. Healthy, one-year-old asparagus crowns should be planted 4 to 6 inches deep in a furrow and spaced 12-18 inches apart.
Rhubarb roots should be planted with the crown buds two inches below the ground in spring as soon as the ground can be worked. The plant requires well-drained soil, rich in organic matter. Consider planting rhubarb in a raised bed in areas where there is poor drainage. Harvest rhubarb during the second year of planting for about a week and for eight to 10 weeks in the third year and thereafter. During the heat of summer, mulch plants with a 2-inch-thick layer of organic mulch, such as compost, straw, or shredded bark. Some issues of rhubarb include crown rot which is typical in soil with poor drainage. This disease damages terminal buds, which results in spindly, weak stems. The cure is to dig out and burn infected plants. Do not replant rhubarb in areas where crown rot has damaged plants before. Leaf spots can attack the plant, with the worst being red leaf, or Ramularia, which can ruin the stems.
For more information contact Jennifer Schutter, field specialist in horticulture, at the Adair County Extension Center at 660-665-9866.