The initial thing a lot of folks wonder after they've decided to grow a garden that season is "Where do I start?" And then the more complex question follows, "Which vegetable crops do I start indoors and which do I plant directly in the garden?" Well, it really depends on the climate conditions of your area, but the gist of it is that the closer you are to the equator the more likely you will be able to sow tender vegetable crop seeds like tomatoes and peppers outside because that climate is predictably warm. But if you are in a more temperate climate (like many of us in the U.S.), you'll need to start your tender crops indoors (either in a greenhouse or growing space in your home) until outdoor conditions are warm enough for you to transplant your seedlings.
That being said, the true first step is to pin point the last frost date of your area and calculate 2 weeks beyond that to get estimate a transplant date for your potential seedlings. Then, countback 8 weeks from that projected date and that is your latest possible indoor sowing date for your tender garden seeds.
Tomatoes, peppers, summer squash, and cucumbers are among the popular tender crops. So, decide how many tender crops you'll want this year and how many cold hardy crops. Once decided, set aside your cold hardy seeds and focus primarily on starting your tender crops. Cold hardy plants and root crops are prime candidates for direct sowing because, as the title implies, they can withstand colder temperatures—in some cases require it, such as broccoli and cabbage. Other directing-sowing prime candidates are determined by the plants inability to withstand root damage when transplanting. So, keep that in mind but seed those seeds aside for a later date.
Before you sow indoors, you'll want to make sure that you have these supplies:
Make sure you have adequate shelf space and breathing space; good airflow promotes healthy growth in the seedlings. We recommend starting your seedlings up to 11 weeks before your projected transplanting date and sow a few each week until the last possible sow date. This gives you the chance to pick the best specimen(s), the ones with the most promising growth, to go in the ground. Maintaining temperature and watering correctly are the most important steps over the next few weeks. Below is a chart of garden crops and flowers with the lowest possible temperature they can stand to germinate.
Water lightly and maintain a moist but not soggy feel. Once your seedlings poke through the soil, begin giving them at least 8 hours of light—many folks provide their seedlings with up to 12 hours of light. Watch your seedlings grow and begin determining which specimens are the most ideal for transplanting. When the time draws near for transplanting, begin checking the tempeprature of your garden bed to minimize transplant shock when you plant your seedlings in the earth. And most importantly, around that time you need to begin hardening off.