Answer: Soil preparation and some planting can begin as soon as the soil is thawed and not too wet/muddy to be worked. Planting depends on what kind of plants you want to grow. Dormant, bare-root plants can be planted very early so they wake up with the season. Container grown or ball and burlap plants that have been stored outside all winter and are accustomed to the cold or are sufficiently "hardened off" can also be planted any time the ground is workable. Most annual and vegetable seeds are planted near the last expected frost date, check your seed packet for instructions. Most annual plants (transplants) are sensitive to or killed by frost so are set out after the last expected frost. Tomatoes, peppers, cucumbers and other plants that are extremely sensitive to cold air and also to cold soil are set out a week or two after the last frost when the soil has had time to warm up. Once the frost date has passed, you want to try to finish planting before the weather turns hot in June. Your local professional nursery staff should be able to help you determine when to plant specific plants as well. You can check your spring and fall frost dates using the maps at (you may need to cut and paste the complete url into your browser to make it work correctly)
Remember that this is an average date so in any given year the actual last spring frost could be earlier or later. I hope this answers your question!
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