Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu
Pea planting has progressed significantly this week and potato planting is well underway. Timing of spring-planted vegetables will depend on soil conditions, soil temperatures, and long-term weather forecasts. We currently are in the optimum planting window for many of those crops in the field. The following are some guidelines for timing spring-planted vegetables from the Mid-Atlantic Commercial Vegetable Production Recommendations:
Asparagus: Plant crowns and transplants April 1 to May 20 when soil conditions are favorable. Early plantings produce more vegetative growth and more vigorous crowns than late plantings.
Beets: Start direct seeding in early April.
Carrots: For early harvest (late June to September), sow March 20 to April 30.
Celery: Start planting May 1 through June. Do not plant too early. After exposure to temperatures below 55°F (13°C) for a number of days, celery (a biennial) initiates seed stalks (bolts).
Cole Crops
- Broccoli – Spring production of broccoli is successful in cooler areas of the region but is limited by heat in southern areas. Use heat tolerant varieties. For spring production transplant March 15 – April 20.
- Brussels Sprouts – Not grown in the spring.
- Cabbage – For spring production transplant seedlings from Mid-March through April.
- Cauliflower – For spring production transplant to the field in early April. Use only heat tolerant varieties.
- Collards and Kale – For spring and early summer harvest transplant or seed starting April 1.
- Kohlrabi – Transplants may be used for a spring crop. Plant in the field at the same time as broccoli or cabbage.
Mustard, Turnip, and Asian Greens: Mustards and turnip greens planted in the spring are susceptible to bolting if exposed to cold temperatures for prolonged periods of time, and only bolt-resistant varieties such as Savanna mustard and Alamo turnip should be grown. Later spring plantings starting in April have a lower risk of bolting. Asian greens are similar. Delay planting until April.
Leeks: For early spring plantings, southern transplants are used. Plant in March through early April.
Lettuce, Endive, and Escarole: The early endive and escarole crop is usually grown from transplants shipped into the region. Lettuce transplants are started in frames or greenhouses. Plants are ready for field planting early March. Direct-seeded lettuce is sown in prepared beds as early in the spring as the ground can be worked. The spring lettuce crop can be field-seeded or transplanted through April.
Snow Peas planted March 14
Onions: For dry bulb onions, sets or seeds can be planted as soon as soil conditions are favorable in the spring; transplants can be planted from March 20 to April 7. For bunching onions, seeds can be planted as soon as soil conditions are favorable in the spring; successive plantings can be made through the summer.
Parsley: Seed is sown 1/3-inch-deep in a well-prepared seedbed as early as ground can be worked in late February/early March through mid-May for late spring/summer harvest.
Peas: Peas thrive in cool weather and can tolerate light frost. Plant peas between February 25 and April 30 when soil conditions are favorable.
Potatoes: The recommended planting dates are March 20 to April 15.
Radishes and Turnips: Seed as early in the spring as soil can be worked. Salad Radishes can then be planted at 8–10-day intervals. Daikon radishes should be planted in April using spring-adapted varieties.
Spinach: Direct seed March 12 to April 20.