First, let's determine our frost dates. In central Illinois our average date of last frost is April 15 -20 with the later date for more northern counties. The first vegetables that can be planted are the very cold hardy ones. These plants withstand freezing temperatures and hard frosts without injury and seeds will germinate readily in cold soils. They can be planted 4-5 weeks before average date of last frost, so mid-March through mid-April.
Very hardy vegetables for extra early planting by seed include: collard, kohlrabi, kale, rutabaga, salsify, leaf lettuce, peas, spinach, and turnips. Spinach and lettuce seeds may even be planted in the fall for spring crops. Hardy transplants include: cabbage, broccoli, Brussels sprouts, parsley, Irish potato sets (baby potatoes), onion sets (baby onion bulbs), asparagus crowns, and rhubarb and horseradish plants.
Frost tolerant vegetables can be planted 2-3 weeks before average frost date, so late-March through April. These vegetables withstand light frosts and seeds germinate in cool soils, but not as readily as the very hardy group. Frost tolerants include seeds of beet, Swiss chard, mustard greens, radish, parsnip, lettuce, carrot, arugula, green onions, Asian greens, and endive. Transplants of cauliflower, Chinese cabbage, and leeks can also be planted now.
Early plantings of cool season vegetables produce the best quality vegetables. In addition many vegetables flourish and produce a crop before all the insects wake from a long winter's nap.
Source: Sandra Mason, Extension Educator, Horticulture, firstname.lastname@example.org
Pull date: April 24, 2009