Get a jump on spring: Start seeds indoors

COLUMBIA, Mo. – It’s difficult to think about gardening in the midst of sweater-weather, but now is the perfect time to start seeds indoors so they’ll be ready for transplant when warmer weather arrives.

There are many advantages to starting seed early. Plants started indoors flower sooner or produce an earlier harvest.

“You can pick new varieties that might not be available in yard and garden stores,” said David Trinklein, horticulture specialist for University of Missouri Extension. “You can also do a better job of timing, so that plants are ready to be moved into the garden when conditions are just right.”

Growing annual flowers and vegetables from seeds starts by choosing what you want to grow. Trinklein said most vegetables take six to eight weeks from the time you drop the seed until its ready to be transplanted in the garden. The exact amount of time varies with species and growing conditions.

“There are references online or available in book form that will tell you how long it takes to produce a transplantable plant of a specific species,” Trinklein said. 

Germination

The germination media needs to be loose, well-drained and fine-textured, Trinklein said. You can buy pre-mixed germination media or create your own by mixing sphagnum peat moss and vermiculite or perlite.

You can purchase bedding plant cell packs designed specifically for starting seeds, but empty egg cartons or similar containers also work. Planting depth varies by species. Trinklein says the rule of thumb is covering seeds about three to five times their diameter.

Each species has specific requirements for germination. Most seed packets list germination requirements.

“For most seeds, germination is accomplished when three things met: adequate moisture, appropriate temperature and oxygen,” Trinklein said.

Accurate temperature control is very important for helping the immature plant emerge from its seed.

“One way is to place electrical resistance cables under the germination trays, keeping the medium at a constant 78 degrees,” Trinklein said.

Germination time varies. Cabbage, broccoli and cauliflower, for example, take only a few days until you see the little seedling peeking through the medium. Something like a tomato might take five to 10 days. For flowering plants, germination time ranges from five to 21 days, depending on the species, he said.

Growing seedlings

After the seedlings can be handled, it’s time to transfer them to a growing-on medium. Those young plants will need light, nutrients, proper temperature and moisture. Trinklein says one of biggest problem with growing transplants indoors is temperature.

“We set our home thermostat for our comfort. Most plants prefer it much cooler at night,” he said.

The ideal temperature for seedlings is 60 degrees at night and 75-80 degrees during the day, Trinklein said. If we keep the temperature too high at night, plants will show spindly growth.

The seedlings will also need fertilizer, but in careful doses because young roots are very tender. Trinklein recommends using half-strength fertilizer for the first few waterings.

“Applying a full-strength fertilizer solution to a young seedling would be like feeding a 6-week-old baby steak and potatoes. You don’t do that,” Trinklein said. “These seedlings need to be nurtured along carefully.”

Moving plants outdoors

As the time approaches for transplanting these plants to the garden, get them ready using a process called hardening.

“About two weeks before transplanting, expose the plants to cooler temperatures and give them less water and fertilizer,” Trinklein said. “This will toughen them up for the move to the garden.”

More information

MU Extension planting calendar, http://extension.missouri.edu/p/G6201.

“Starting Plants Indoors From Seeds,” http://extension.missouri.edu/p/G6570.

“From Seed to Harvest and Beyond: MU Extension Garden Journal and Calendar,” http://extension.missouri.edu/p/mp928.