The Basics of Starting Your Garden from Seed or Seedlings

A good seedling growing spot is one with bright light, preferably some direct sunlight. Seedlings may also be grown under a grow light but should be positioned only a few inches from the tubes for the most light possible. If you do not have a good location in your home to grow seedlings, purchase healthy greenhouse-grown plants at the proper planting time.

Seedling Basics

Most seeds germinate best at a temperature of about 70 degrees. Cool-season crops, such as cabbage and broccoli, will become leggy if started at temperatures too high, so they should be germinated at temperatures from 55 to 60 degrees. After germination, plants need temperatures about 10 degrees cooler than the germination temperatures.

Clean containers, as well as a sterilized seedling mix, are important to germination. You can sterilize clay pots, plastic pots, and flats in a dishwasher or wash pots by hand in hot soapy water. Chlorine bleach will also disinfect wooden flats.

Wash and disinfect work surfaces and tools so your clean potting mix will not become contaminated. If, after plants emerge, you notice a spot where seedlings begin to die, immediately and carefully dig out that infected spot so the disease will not spread to other areas of the pot or flat.

When to Start Your Seeds

The time required to grow a seed into transplanting size may range from 3 to 14 weeks. Sow seeds at a time that will allow enough but not too much growing time before plants are set outdoors. Some plants will not tolerate frost. In some seasons earlier outdoor planting may be possible, but risk is always involved.

Cool-season crops, such as head lettuce, broccoli, cauliflower, and cabbage have frost tolerance and can be planted outdoors before the frost-free date. They need about 8 weeks to develop indoors. Therefore, to have them ready for planting outdoors at the proper time, sow them promptly.

Plants with small seeds such as begonia and lobelia require 12 to 14 weeks to develop. They should be planted promptly for late May planting. Seeds of garden flowers such as petunia, geranium, snapdragon, and impatiens need 10 to 12 weeks to develop, so prompt planting is also needed to have planted large enough to place outdoors in May. Even now, plants will probably not be flowering when planted outdoors, but they will develop quickly and flower soon after they are established.

There is still time to start seeds of many other plants. Vegetables such as tomato, pepper, and eggplant will be large enough for outdoor planting after 7 or 8 weeks. Flowers that also need about 8 weeks to develop include verbena, ageratum, coleus, vinca, salvia, sweet alyssum, and nicotiana. Celosia, marigold, nasturtium rose moss, and balsam reaches transplanting size in about 6 weeks. Zinnia, cosmos, amaranth, cleome, and hollyhock are ready in only 4 weeks.

Earlier production may also be possible if vine crops such as cucumber, squash, cantaloupe, and watermelon have seeds started indoors. Seedless watermelons tend to have less vigor than normal types and germinate better indoors. However, these crops should be started only 3 to 4 weeks before the frost-free date so they will not become too large or stunted in the pots.

Vine crops should never be planted outdoors until soil is well warmed. Remember that seedlings grown indoors need gradual adjustment to outdoor conditions. Place them outside in protected, light-shaded areas for one to two weeks before you move them into exposed locations in the vegetable or flower garden.