Planting after last frost?

Usually as soon as you can easily crumble the soil. You might want to check some internet sites for "seasons" in your area. There's one on the Weather Channel -- tells the last date for "frost". The Farmer's Almanac is another great source -- not knowing whether you are in Florida or Alaska makes a difference. Keep some old cotton lightweight curtains -- or similar, in case Mother Nature goes wacky again. Do NOT use plastic. Soft, lightweight cloth only. Stay tuned to local evening newscast; they will warn you about any late frost.

at least 2 weeks because last frost is and average and frost can come after average late frost so at least 2 best 4 weeks

Southern England...now! otherwises wait til lst May,or cover at night

If you use ground warming techniques you can plant almost straight away!