Plant cool weather crops when the soil has thawed enough to work in the spring, and plant warm weather crops after the last expected frost of the season. Plant tender bulbs in spring, and cold-hardy bulbs in autumn before the first frost of winter. To determine the specific planting dates for each type of crop in your region, contact the state Extension office, or visit the state's Extension website.
In regions with short growing seasons, plants are often started indoors 6 to 8 weeks before the first frost of the season and transplanted to the garden after the danger of frost passes. Plant cool-weather crops, such as leeks, cabbage and broccoli, in early spring or autumn.
As cool-weather crops can tolerate freezing and below freezing-temperatures, they are often planted in winter gardens. Cool-weather crops continue to produce several weeks after the first hard frost of the season.
Plant semi-hardy vegetables, such as Swiss chard and English peas, anytime from spring through autumn. Semi-hardy plants produce year-round in regions with mild winters. Warm weather crops, such as tomatoes, pumpkins and peppers, grow best when temperatures range from 65 to 90 degrees Fahrenheit. Plant these, and other cold-sensitive crops, after the danger of frost passes in spring.