Early spring is the proper time for several vegetables and flowers. Cool-season vegetable crops, such as cabbage, lettuce, and peas grow best in cool temperatures. Others, such as onion, require a long growing season and should be planted in early spring for maximum crop yields. This listing is designed for central Iowa, northern Iowa would be about one week later, about one week earlier for southern Iowa.
- Radishes - Spring radishes are a cool season crop. They can be planted as soon as the ground can be worked in late March or early April. Most cultivars mature in 20 to 30 days. For a continuous harvest, sow seeds every 7 to 10 days until late spring. High temperatures cause bolting (flowering) and the roots become soft.
- Broccoli, Cauliflower, and Cabbage - Broccoli, cauliflower and cabbage are cool season vegetables, which grow best in temperatures between 60 and 70 F. However, exposure to prolonged periods of temperatures below 50 F may cause premature head development or buttoning. In central Iowa, plant broccoli, cabbage, and cauliflower in mid-April.
- Lettuce, Spinach, Collards, and Kale - Quality of these plants are reduced with the onset of hot weather due to seed heads and bitter taste.
- Onions - Plant onion seeds, sets, and plants as soon as the ground can be worked in the spring (late March or early April in central Iowa). Long-day varieties are the best choice for Iowa gardeners.
- Peas - Garden, snow, and snap peas should be planted as soon as the ground can be worked in spring. The crop should be mature in approximately 60 to 70 days.
- Carrots - Carrots can be sown from early spring to early August. For an early crop, sow seeds in early to mid-April.
- Potatoes - Plant certified disease-free potatoes as soon as the ground can be worked in spring. Large potato tubers should be cut into pieces, each containing 1 or 2 growing points or "eyes". Small potatoes may be planted whole.
- Beets and Swiss Chard - These are other vegetables to plant early through August 1.
- Pansies - Will withstand late seasons frosts. Prefer cool weather and tend to decline with the onset of warmer weather.
- Roses - If necessary, transplant roses as soon as the ground can be worked in late March or early April. Bare-root roses should be planted immediately after purchase. If planting must be delayed, place the bare-root roses in a cool location, such as the garage or refrigerator, until they can be planted.
For more information on planting vegetables, see extension publication Pm-534, Planting and harvesting times for garden vegetables or Pm-819, Planting a home vegetable garden.
This article originally appeared in the March 21, 2003 issue, p. 29.