Plant "starts" — those six-packs or small potted seedlings — are available in stores, but there are several good reasons to take the time to grow your own seeds.
First, you can grow the specific plant varieties you want, not just those found in nurseries. Heirloom plants, which have enjoyed popularity in the last decade, can be less easy to find in nurseries. Other good reasons to grow from seed are decreased cost and, if you pay careful attention, healthier and stronger plants to put into the ground.
If you're ready to give it a go, realize that gardeners have endless discussion about the details of starting seedlings. Fine points aside, all you really need are suitable pots, a warm place to put them and a good seed starting medium.
Starting plants in anything other than the ground they will eventually mature in will cause some degree of transplant shock. For this reason, growing one to three seeds in individual containers is recommended, especially for new gardeners. More experienced gardeners may want to sow their seeds in large flats and transplant to smaller pots later
Some people invest in peat starter pots or other containers. Seed starters with 20 to 40 individual wells allow you to start most of your plants in one tray. However, you can actually grow your seeds in any small pot, including used yogurt containers or old plant six-packs. Just make sure whatever you use has holes for drainage and has been thoroughly washed in hot water.
Choose your planting medium carefully. "Be sure and look for 'seed starting mix' on the label," says Jennifer Loizeaux, assistant grower at Ashland Greenhouses. "It is possible to get good results with a good potting soil, but you want something very light. Seed starting mix is more porous, and usually has more peat and perlite."
Moisten the soil before placing in the pots. It's important to read individual seed packets for planting depths. And don't forget to mark the plants with name and planting date in indelible ink. Wooden popsicle sticks or plastic knives are good for plant tags. At the OSU extension garden, Master Gardeners use the old slats from mini blinds for labeling plants.
Reading the packets will also identify which seeds need special treatment. Germination can be improved in some varieties if you soak them overnight before planting. Others need scarification with a sharp blade, or refrigeration to help them along. Some seeds need light to germinate; others need to start in darkness. Group them together by these needs.
After planting, cover with plastic bags or plastic wrap (don't allow the plastic to touch soil). Set in a warm place, out of drafts, in darkness if needed, or in light. Check every day to see they stay moist, but you shouldn't need to water.
Most seeds will germinate in 7 to 14 days. Once the first sprouts appear you can remove the plastic covering and set in full light. This prevents their getting "leggy" when they stretch for sunlight. For humidity, spread the bottom of a tray with large pebbles and add water, but not to cover. Place your pots on the rocks.
Once the seedlings are 1- to 1-1/2-inches tall, you can start hardening them off. This is an important step for successful transplanting. Put the plants outside every day for a few hours. Build up their time in the sun gradually from a few hours to all day. By the end of a week the seedlings should be ready for transplanting, as long as danger of frost is past (mid-May is safe).
Add fertilizer to the planting bed according to package directions. "Just tease the seedling roots out of the pot and move them really gently," emphasizes Master Gardener Linda Holder. Don't plant your seedling into the ground any deeper than it was growing in the starter pot. Use gentle watering to settle the soil around the new plant, rather than packing soil down with your hands.
The next step is easier: water when needed and watch your garden grow.