You want to wait until the soil is warm (in the 60s°F), and all danger or frost has passed. You can get a rough estimate of your last frost date here : http://www.almanac.com/tool/frost-dates-calculator . Keep an eye on local weather forecasts, too. If you put the seedlings in cold ground they’ll die. See above: You want these to be 3 to 4 inches tall, too.
You want to wait until the soil is warm (in the 60s°F), and all danger or frost has passed. You can get a rough estimate of your last frost date here : http://www.almanac.com/tool/frost-dates-calculator . Keep an eye on local weather forecasts, too. If you put the seedlings in cold ground they’ll die. See above: You want these to be 3 to 4 inches tall, too.