When should you start seeds indoors? That depends on the type of seed and the last expected frost date for your area. Frost dates are averages and are given as a range of dates. Once you know your last expected frost date, your seed package should tell you how many weeks ahead you should start the seeds. Count back from the last expected frost date for each type of seed you are planting and you'll have a planting schedule.
If you live in USDA Zone 6 (Frost Free Date Range March 30 - April 30) and you want to plant broccoli, which should be started 5-7 weeks before the Frost Free Date, count back 7 weeks from March 30th to February 9th. That's the earliest you should consider starting your broccoli seeds. If it seems like it will be an early spring, go ahead and start planting then. However, you would probably be better off averaging the dates to April 15th and counting back from there. Holding the seedlings for a couple of weeks before transplanting won't be as stressful on them as holding them for an entire month.
Last Expected Frost Dates by Zone
- Zone 1: June1 - June 30
- Zone 2: May 1 - May 31
- Zone 3: May 1 - May31
- Zone 4: ;May 1 - May31
- Zone 5: March 30 - April30
- Zone 6: March 30 - April30
- Zone 7: March 30 - April30
- Zone 8: February 28 - March 30
- Zone 9: January 30 - February 28
- Zone 10: January 1 - January 31
- Zone 11: Frost Free Year Round