How early you can plant your garden vegetables depends upon the hardiness of the vegetable and the climate. In the Columbia Basin, generally, our frost-free dates are May 15 through Oct. 15. Vegetables are classified as very hardy, frost-tolerant, tender and warm-loving. This is based according to their ability to withstand freezes, cold temperatures or heat.

Our growing season is basically 150-180 days in length. Some years we have very warm weather early in the season, so you may find that cool season crops such as spinach, cabbage, broccoli, cauliflower, lettuce, et cetera don’t perform well. If the weather is too hot too early, these crops develop too quickly. The result is poorly-formed heads of cauliflower, broccoli, cabbage, and brussels sprouts and the possible bolting (going to seed) of radishes, lettuce and spinach. Be sure to plant these crops at the right time to make the most of the cool spring weather.

Cool season vegetables for early spring planting

Very hardy: Plant four to five weeks before the average frost-free date: Kale, kohlrabi, leaf lettuce, pea, onion, rutabaga, salsify, spinach and turnip can be planted by seed.

Asparagus crown, broccoli, brussels sprouts, cabbage, horseradish root, onion plant or set, parsley, potato and rhubarb can be planted as transplants, being started first indoors.

Frost-tolerant plants: Plant these two to three weeks before the average frost-free date: Beet, carrot, chard, mustard, parsnip, radish, cauliflower, Chinese cabbage and herbs.

Warm-season vegetables for late spring planting

Tender plants: Wait to plant these on the average frost-free date: Snap beans, sweet corn, summer squash, New Zealand spinach can be planted as seeds. Tomato transplants can be planted at this time also.

Warm-loving plants, those to plant one to two weeks after the average frost-free date, include lima beans, cucumber, cantaloupe/muskmelon, okra, pumpkin, winter squash, watermelon and eggplant can be planted from seed. Plant the pepper transplants at this time also.

Now that we’ve talked about average frost free dates for gardening, I’ll mention planting according to soil temperature. Following the soil temperature for planting seems to take some of the guess work out of planting for me. References I use are the Vegetable Gardening in Washington State, EM057E, page 8 and 9 on the web at pubs.wsu.edu. Another web source for information to gather the current soil temperatures titled AgWeatherNet. Make sure and look around the site to find the information that best suits your planting area, weather.wsu.edu.