As we get closer to the average frost free date, it is time to be thinking about finally putting some plants in our vegetable gardens. To ensure a successful growing season and harvest, there are a couple of rules to follow.

Crop rotation is one good practice to follow. Rather than putting the crops in the same location every year, crop rotation moves the locations where different plant families are put in the garden. Moving the plant families around can help to reduce insect and disease damage which tends to increase when the host plant is continuously grown in the same location. A good crop rotation schedule should rotate the plant families around so they aren’t grown in the same location for about three to five years. The difficult part is knowing what vegetables are related. A quick ‘family tree’ will help you know which plants in the vegetable garden are related and to help with crop rotation.

• Fabaceae (Bean) family- pea; snap, cow, and fava bean
• Brassicaceae (Cabbage) family- cabbage, broccoli, cauliflower, Brussel sprouts, collards, kale, turnip, rutabaga, kohlrabi, Chinese cabbage, radish
• Cucurbitaceae (Cucumber) family- cucumber, summer squash, winter squash, cantaloupe, watermelon
• Chenopodiaceae (Goosefoot) family- beet, Swiss chard, spinach
• Liliaceae (Lily) family- onion, garlic, leek, shallot, chive
• Apiaceae (Parsley) family- carrot, celery, celeriac, parsnip, fennel
• Solanaceae (Nightshade) family- tomato, eggplant, pepper, potato, tomatillo

Just how early can you plant in the garden? Some crops could have actually been planted over a month ago, but that doesn’t mean they were immune from the cold temperatures and snow. The best way to determine planting date is to check soil temperatures. Seeds have a minimum, maximum and optimum soil temperature at which they will germinate and seedling growth begins. If planted too early, when soil temperatures are cold, seed germination and seedling growth will be very slow leading to seeds rotting, damping off disease, or low vigor plants with lower yields. Know what minimum and optimum temperatures are needed for different vegetables and monitor soil temperatures to determine the best time to seed. Planting early does not guarantee an earlier harvest if soil temperatures are too cold for germination. If you don’t have a soil thermometer handy, there are some general timelines to follow:

• 60 days before average last spring frost date – collard, onion sets, garden pea, radish, spinach, turnip
• 50 days before average last spring frost date – swiss chard, leek, mustard, potato
• 40 days before average last spring frost date – beet, cabbage transplants, carrot, lettuce
• 30 days before average last spring frost date – broccoli, Brussel sprout, and cabbage transplants; Chinese cabbage
• 10 days before average last spring frost date – sweet corn, sweet potato, tomato transplants
• Average last spring frost date – bean, cucumber, eggplant transplants, muskmelon, pepper, pumpkin, summer squash
• 10 days after average last spring frost date – okra, watermelon

Before we know it, warm weather and spring-like temperatures will be here to stay. With a little bit of help, you can guarantee a healthy and productive vegetable garden.

For more information contact Elizabeth Killinger at elizabeth.killinger@unl.edu, 308-385-5088, on Facebook, Twitter, her blog at https://huskerhort.wordpress.com/, or visit the University of Nebraska-Lincoln Extension website: hall.unl.edu.