University of Illinois Extension

Starting Annuals from Seed

If you are thinking about starting seeds indoors this spring, you need to ask two questions. “First, are you willing to devote the time and energy necessary to ensure successful transplants?” said Martha Smith, U of I Extension horticulturist. “Second, do you have the proper space and adequate growing environment?”

Many annuals and vegetables require such a long growing season that they won’t flower or fruit if they don’t get a head start indoors, leading some gardeners to consider the indoor head start.

“Depending on what you are trying to grow, this project could be four weeks, six weeks, or as long as 12 weeks,” she said. “All seeds have different requirements. Read the back of the seed packet in order to determine when you need to start your seeds.

“Don’t wait until a beautiful spring day in May to start your seeds--you will be disappointed that you didn’t read the instructions earlier. Once started, these plants will need regular maintenance such as watering, fertilizing, and transplanting to larger containers. This is the process greenhouse growers are going through this time of the year. When you buy your transplants in the spring, you are paying for materials and labor needed to produce the crop.”

Gardeners often hate to throw away even the scrawniest plants. When starting seeds, you may end up with one hundred seedlings that will need to be transplanted to cell packs and placed in flats. One-hundred seedlings translate into approximately three flats of 36. Do you have a large enough space with the proper lighting and growing conditions to successfully grow these plants?

“Selecting the strongest and healthiest seedlings and discarding the rest is necessary if you have limited growing space,” she said.

The growing environment requires light--natural or artificial. South-, southeast-, or southwest-facing windows will give sufficient direct sunlight in the early spring months. Turn the trays or pots each day to keep the seedlings straight. If you have insufficient natural light, you will need to provide artificial light.

“Fluorescent lights work well,” she said. “Set up your grow lights so they can be kept one to two inches above the seedlings. You will have to suspend them on adjustable chains or pulleys to keep the light at the proper distance as your seedlings grow. Artificial lights should be set on timers to provide between 12 and 16 hours of light every day.”