How to start garden seeds indoors

Last Updated: 
February 28, 2008

EUGENE, Ore. – It's time to start flexing your green thumbs and studying seed catalogs if you'd like to grow your own veggies, fruits and flowers from seed this year.

If you start your own plants from seeds, you'll have a much wider choice of varieties to grow in your garden. Some of the earliest plants that can be planted out into the garden are members of the cabbage family - including broccoli, Brussels sprouts, cabbage and cauliflower. They grow to transplant size in four to six weeks.

For example, seeds started in mid-March should be ready for the garden by May 1, according to Ross Penhallegon, horticulturist with the Oregon State University Extension Service.

No matter where you are in Oregon, tomato, pepper and eggplant require six to eight weeks from seeding to transplanting. To transplant them out in mid-May, start the seeds indoors the last half of March. If you live in the colder regions of the state you will have to adjust accordingly and start your seeds later and plant out your starts in the garden a few weeks later.

Cantaloupe, watermelon and pumpkins develop transplants in about four weeks. Start melons and pumpkins from seed planted into individual containers in early April for transplanting in May. Or wait and plant melon and pumpkin seeds directly into the garden when the soil is warm enough. Melons and pumpkins do not withstand transplanting as well as other vegetables and the harvest time is virtually the same with direct seeding.

Plant seeds for transplants in a homemade mix containing equal parts of sand, loam and peat moss, or purchase commercial potting or rooting mediums that are soil-less and sterile such as mixtures of perlite, vermiculite and organic materials. The mix needs to be well drained. If your seeds are saved from previous years, test them for germination before you do all the work of planting.

Place seeds in a damp paper towel and put them in a warm place, such as on top of your water heater. If less than half the seeds germinate after a few days, you might consider buying fresher seeds.

Fill the desired container with a lightly moistened soil mix. A four-inch flowerpot may be seeded with 18 to 20 seeds. Cover the seeds with one-quarter inch of soil. Then label the pot and place it in a plastic bag. Tie the bag so moisture does not escape. No further watering is needed until the seedlings appear.

Keep the germinating seeds at room temperature (68-75 degrees). As soon as plants emerge, remove the bag and expose the plants to maximum light.

Time until seed germination will vary with the type of vegetable you are starting. Cabbage germinates in a couple of days. Tomatoes may take four to six days and peppers, 10 to 14 days.

After germination, keep seedling pots at lower temperatures (55 degrees at night, 65-70 degrees during the day). Unless the soil mix was fertilized previously, weekly applications of a soluble plant food are recommended.

When your seedlings get their first true leaves, it's time to separate them. Carefully loosen the soil around the roots with a dull knife blade. Place each plant in a three-inch pot, or space six to eight plants in a larger plastic or pressed paper container.

Uniform watering and fertilizing, and at least 12 hours of sunlight daily, will produce a stocky transplant with good production potential. About 10 days before transplanting to the garden, expose the plants to cooler temperatures and slightly less water. Leave the starts out all night the week before transplanting. Avoid frosty periods.

"If you've done everything right, the final product is a stocky transplant six to eight inches high with a healthy dark green color," said Penhallegon.

Three days before transplanting, water your started plant well with a complete soluble fertilizer. When setting transplants in the garden, use plenty of water around the roots to be sure they have good contact with the soil.

To learn more about growing transplants at home download OSU Extension Service's fact sheet "Producing Transplants at Home," (FS 225) from the Web.

Author: Carol Savonen