1. Sow the seeds.
I use 2"-deep plastic flats that are about 11"x21", which are available for under $2.00 at home centers. In these I place sectional seed starter packs which have nine 1" cells each. Eight fit in a tray. These are harder to find but are available at Orchard Supply Hardware and some nurseries. The individual paks have drainage holes and drain into the tray. If you can't find them, they can be specially ordered through this web site.
Fill each pak with finely ground potting soil (coarse planting mixes are not good for starting seeds.) Gently press the soil down and make a depression in each cellfor the seeds. Sow seeds according to directions on the pack. Most seeds can safely be covered planted three times their diameter. Some seeds need light to germinate so they should be covered very lightly if at all.
Since not all seeds germinate, you may want to plant two seeds in each cell, and then transplant or discard the extras so you have one plant in each tray after sprouting. Be sure to put a label or other tag on each pack so you don't forget what you are growing. I use 4" wooden coffee stirrer/ ice cream sticks -- they are cheap and easy to use.
2. Keep flats moist and warm.
Pour some tepid water in the bottom of each tray to a depth of 1/2 to 3/4 inches. Because the watering is done from the bottom of the flat, seeds don't get washed out or disturbed. The trays also provide a water reservoir that can help keep your growing medium moist but not soggy. Never allow the soil to dry out completely.
Most Spring and Summer plants, especially vegetables like peppers and tomatoes, need warmth to germinate. A good place to keep the trays temporarily until the seeds germinate (assuming they are warmth loving species) is the top of the refrigerator. It's usually nice and warm up there. Be sure to check them regularly for water and germination, so the seedlings don't dry out or start growing too much without sufficient light.
3. Provide light
Once seeds germinate, they need light. If you have a sunny window, you could keep the trays by the window but that is not always practical. Besides, few homes have windows that provide direct sun for six hours a day. Instead, I use the standard shop lights with fluorescent bulbs. Two shop lights each with two 48" florescent tunes is sufficient for four of the trays described above. That's enough to start at least 288 plants! Make sure to locate the lights on a shelf in a warm part of the house, unless you can provide a separate source of heat for the seedlings. (Less warmth is needed once the seeds sprout, so you don't have to keep them on the refrigerator.) If you use a closet, be sure to leave it open enough so the plants get air circulation to discourage mold and mildew.
This shop light set up only requires a shelf space about 12" x 48" in size. The shop lights should be hung on chains so that they can be adjusted in height. Initially, the lights should be just a few inches from the tops of the sprouting seeds, and then raised as the plants grow.
There are special wide spectrum florescent bulbs available for growing plants, but they are fairly expensive. Standard bulbs have given me good results over the years. I place pieces of cardboard wrapped with aluminum foil on three sides of the trays to help reflect as much light as possible.
The seedlings should get 16 hours a day of light, so it's a good idea to plug them into a timer that will automatically turn the lights on about 6:00 a.m. and turn them off around 10:00 p.m.
4. Transplant seedlings.
When seedlings get too tall to remain under the shop lights, it's time to transplant them. Hopefully, you have timed this so it's warm enough to put them outside. You may wish to first transplant them into large containers Transplanting gives plants room to grow and improves air circulation. It also stimulates the growth of bushier feeder roots.
Fill the transplanting pots with moistened potting soil, preferably
the same type used to start the seeds. Firm the mix in the pot, leaving
enough room to place the root ball of the seedling so it is below the top
of the pot. I use 8 ounce yogurt cups with drainage holes poked in
the bottom. These are free and a good way to reuse containers.
Gently remove plants with root ball intact from the starting pack cells,
place in the pot and fill in around it with potting soil. Be sure
to gently press the soil down and water the plant thoroughly.
5. Harden Plants Off
If you can raise the lights high enough, you can keep the plants indoors if the weather is still cool. Preferably, if the day time temperatures are warming (at least 65º for tomatoes and 70º for peppers), you can put them outside for a few hours a day to gradually accustom them to sun light and outdoor air. Be sure to introduce the plants to direct sun gradually. It is best to start them off in filtered sun such as under a tree, and over several days give them more and more time in more direct sun. Putting young plants in direct sun right away will usually cause leaf burn and shock. If night time temperatures are still cold, be sure to bring the plants inside every evening until it has warmed up.
6. Plant Outside
Once you are satisfied the plants are hardened off and the weather is reliably warm, plant them where they are to grow. Be sure to keep newly planted areas well watered to encourage the roots to grow into the surrounding ground and prevent shock.
Enjoy Your Garden!
Once the weather gets warm, your Spring and Summer garden should grow rapidly. Before long, you should have lots of tomatoes, peppers, flowers, or whatever else you planted! Send me your garden photos ... maybe they could be shared with the whole gardening world on this site!