With each type of vegetable and flower seed having a certain growing time before transplanting or planting directly in the soil, I found it very helpful to create a seed starting calendar when I first started gardening. Even though my calendar is based around weekends during our second year of gardening, I still find its setup helpful today. In fact, it’s so helpful, I never took the time to type the calendar into the computer!
The most essential date for your seed starting calendar is the last frost date for your area. Since seed packets usually tell you to start your seeds a number of weeks before your last spring frost date, you need the actual date. However, keep in mind that frosts still can occur after the last spring frost date. You’ll need to keep an eye on the weather report to find out if the frost will be a light freeze (killing tender plants with little destruction to more established ones), moderate freeze (widely destructive effect on most vegetation, with heavy damage to fruit blossoms and tender and semi-hardy plants), or hard freeze (damage to most plants).
Victory Seeds has a listing of all the frost dates for the United States.If you can’t find your place, check the original NOAA report (pdf) Make note of the first fall frost date, too, since that will give you an idea of a typical growing season for your area. If you are in the upper or lower end of a hardiness zone, your frost date may be later or earlier than the listed date.
Look at the your seed packets and sort them into several piles. Generally, cold weather crops like broccoli are started sooner than warm weather crops like tomatoes and peppers since they can tolerate the cooler spring temperatures. Separate seeds that can be direct sown into the ground, and make a note on your calendar when to direct sow them.
Also think about where you will be starting your seeds.A cool basement will slow germination adding on about a week to your seed starting date. A warm, sunny window will speed up the process by a week. If you plan on using row covers or some type of protection for your plants to extend the growing season, start your seeds a little earlier.
Base your calendar on when you have time to plant outdoors in the spring.If you have a busy weekday schedule and free time on the weekends, plan accordingly. Harden off your transplants over a 7 to 10 period, and include the start of the hardening off period on your seed starting calendar.