Home and Garden

Get to know the seed-starting basics

By Deborah J. Benoit

Are you ready for an early season gardening adventure?

Seed displays are prevalent right now in stores from garden shops to supermarkets. So grab a pack of seeds (or two or three) to start indoors. With a few basic supplies, by the time the weather is suitable for planting outside, you’ll have some home-grown additions ready for your garden.

The seed packet provides information on when to plant seeds for an early start on the gardening season. Usually it will suggest a number of weeks before the anticipated last frost date in your area. That date represents the earliest average date to plant outdoors.

Not sure when that is, visit: garden.org/apps/frost-dates.

Select a container. Seed-starter trays with clear domed covers are available in various sizes, some with inserts for individual cells. You can even opt to recycle food or beverage containers you already have at home. Just be sure to punch or drill holes in them to allow drainage, and add a saucer for water.

Next, fill the container with seed-starting mix. You could also use potting soil, but never use garden soil because it’s too heavy for germinating seeds in containers. Another option is coir (coconut fiber) or peat pellets (which are compressed and expand when moistened). Whatever growing medium you choose, be sure to moisten it first.

Sow seeds according to the guidelines on the seed packet. Gently cover seeds with growing mix and water lightly. If you’re starting more than one type of seed, be sure to add labels. You’ll thank yourself later.

Cover the container, either with the dome provided with the seed-starting tray or a clear plastic bag to keep the growing medium from drying out. It should remain moist but not wet.

If condensation appears, remove or vent the cover. Too much humidity can cause seeds to rot. Once seedlings emerge, remove the plastic to prevent failure due to “damping off.” For more information about “damping off,” visit: go.uvm.edu/damping-off.

The seedlings will need light, lots of it. While a sunny windowsill may work, relying only on natural light can result in tall, spindly seedlings weakened by their efforts in search of more light. Using artificial light to supplement or replace sunlight provides a higher and more consistent level of light. Plan to leave lights on 14-16 hours a day. 

Providing supplemental light can be as simple as hanging a shop light with a fluorescent bulb above the seed-starting tray. Grow lights are another option. Whatever you decide, adjust the height of the light above the seedlings to keep it no more than a few inches above them to ensure that they receive sufficient light.

As they grow, thin out excess seedlings, selecting the strongest and pinching off any others that will compete for water and nutrients. Once the seedlings develop their “true leaves,” they can be fertilized with a half-strength solution (based on package directions) when watering.

Before moving plants outside, they need to be hardened off by gradually introducing them to sunlight. To do so, move them outdoors during the day, at first in dappled shade and then gradually to more sun over the course of a week or two. 

Whether you start seeds because you want to grow an unusual variety not available as a plant or want to save money by starting multiple plants of the same kind, growing plants for your garden from seed is an easy and interesting addition to your gardening adventures. 

Deborah J. Benoit is an extension master gardener through the University of Vermont.

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