|If I want ripe tomatoes in my garden by May 1st, when should I plant the seeds in my greenhouse?|
|The short answer is now, but there's no guarantee that you'll get tomatoes on May first from plants set outdoors.|
Here's the math:
You're in zone 7 with an average last frost date of mid-April. Based on that, you can safely set your tomato transplants out on the first of May.
Tomato seeds take 7-10 days to germinate, and about 6 weeks to grow to transplant size. They won't produce blossoms and fruit for probably another 3 weeks, once they're planted outside. In order to set fruit, tomato plants need nighttime temperatures consistently above 55F degrees.
Your best chance to get tomatoes by May first is to grow your plants in your greenhouse rather than set them outdoors. If you're willing to wait until later in the season for harvesting, start your seeds now, and set them outside in May. You'll still be the first one on your block to pick a ripe tomato - it just won't be on May first.