Question: When is the time to start vegetables and annual flowers indoors to plant outside in spring?
The time to start seedlings indoors depends on plants’ individual growth rates and the recommended dates in your area for putting plants in the ground. To figure the seed-starting date, start with the recommended planting time, calculate the plant’s germination and growing time (often noted on the seed package), and count back the required number of weeks to reach the date for starting the seeds.For example, to grow seedlings of a warm-season flower like zinnias in Middle Tennessee (where The Garden Bench calls home), we can plan on putting transplants in the ground after mid-April, the area’s last average frost date. The approximate growing time for zinnia seedlings is about 4-6 weeks, so you can sow zinnia seeds indoors early- to mid-March. Tomato seeds, another warm-weather favorite, can be sown in flats indoors 5 – 7 weeks before it’s time to transplant, so we can plan on starting them early in March.
To start cool-weather vegetables indoors, begin much earlier. For example, some leaf lettuces can be started indoors 4 weeks before the soil outdoors can be worked; bigger, tougher cool-season favorites like broccoli and cauliflower need 5 to 7 weeks to reach transplanting size. Sowing indoors now until the end of January can provide transplants ready to go in the ground at the end of February.
Give the seedlings plenty of light and the recommended moisture as they grow, and harden them off – expose them gradually to outdoor weather – before planting them in the ground.