In the Garden: Give seeds a good start with the right containers, soil and light

Seed-starting is the most important skill a gardener should have. While it might be easier to purchase seedlings at garden centers, growing your own plants from seed has benefits.

For one thing, you can grow unusual varieties that aren’t available elsewhere. It’s also more economical to grow a bunch of plants for the price of a packet of seeds.

You will need containers with drainage holes, a sterile seed-starting mix, clear plastic domes or bags to cover your containers, and a light source.

Garden centers sell seedling flats without drainage holes that hold flat inserts with holes. These inserts come in sheets with different sizes of cells for planting your seeds in. Compressed peat pellets are another option: just rehydrate them, plant a seed into each one, and later plant each seedling – including the pellet – directly into the garden.

If you’d rather recycle some common household items for seed-starting containers, consider making individual pots with strips of newsprint, or using egg cartons, to-go containers, yogurt cups, plastic storage containers, or flower pots. Add drainage holes to all of these.

Look for seed-starting mix (also called germination mix) at garden centers. It is important to use a sterile mix since young seedlings are susceptible to disease. Avoid using garden soil as it compacts easily and can contain pathogens.

A clear plastic dome lid or bag increases the humidity around your plantings, thus facilitating germination (sprouting). The lid or bag is only left in place until the majority of seeds have sprouted.

Consider picking up some finely milled sphagnum moss at the garden center. This is a natural inhibitor of a seedling-killing fungal disease called damping-off and is sprinkled on the surface of the seed-starting mix after the seeds have been planted.

Having a light source for your seedlings is very important. According to Leslie Halleck, author of “Plant Parenting” (Timber Press), “Seedlings require intense amounts of light for specific durations; most windowsills simply are not bright enough, for a long-enough duration, for healthy seedlings.”

In the past, I’ve suggested sunny windowsills as good alternatives to commercial grow lights, but it is so important to meet the seedlings’ light requirements so they won’t stretch toward the light. If you’ve had good luck with a bright spot in your home, however, go with what works.

Here are the basic steps for seed-starting:

1. Begin with clean containers; if they’ve been used before, wash them in a mild bleach solution of one part bleach to nine parts water.

2. Lightly moisten the seed-starting mix and fill the container to a depth of 2 to 3 inches. Press it down gently to compact it.

3. Referring to the seed packet, plant the seeds at the recommended depth.

4. Sprinkle a very light layer of finely-milled sphagnum moss over the soil surface.

5. Cover the container with a clear dome lid or clear plastic bag.

6. Place the container under a grow light or in a very bright location.

7. Remove the cover once most of the seeds have germinated. Monitor the soil moisture so it doesn’t dry out.

8. Once the seedlings have a set of mature leaves, begin feeding them with a diluted nitrogen fertilizer such as fish fertilizer.

9. When roots begin emerging from the bottom of the container, move seedlings into a larger pot if it’s too early to plant them outside.

10. A week prior to transplanting them in the garden, slowly expose the seedlings to sunlight and temperatures to acclimate them.

To learn more about seed-starting, watch this week’s “Everyone Can Grow A Garden” video at youtube.com/c/susansinthegarden.