Editor’s note: (This is the second of a 3-part series on growing plants from seeds.)
Growing plants from seeds can save you money, and give you many more plant varieties to choose from. If you provide the conditions they need, seeds will germinate and grow into healthy plants. Here’s how to get them growing.
What you plant the seeds in is important. The medium must be fine-textured and uniform; well aerated, but capable of holding moisture; have low fertility; and be free of insects, weeds and diseases.
The most popular starting media are peat-based, with vermiculite, perlite, or ground pine bark added. You’ll find these in seed starting kits at the home center or nursery, or in seed catalogs. Don’t use garden soil, potting soil, or topsoil: they are too heavy and do not drain well enough for germinating seeds and growing tiny seedlings.
Many different plastic containers for starting seeds are available. Compressed peat pots and peat pellets (that expand when soaked in water) are also good choices. But a wide variety of household containers will do just as well. Butter tubs, Styrofoam cups, cut-off beverage cartons, or anything else you have will work. Poke several holes in the bottom to allow for drainage. Wash the container completely, then sterilize by soaking in a 1% bleach solution for a few minutes, and allow to dry.
Some terms need clarifying. Most seeds are sown in a “seed flat.” Seedlings are transplanted into a “pot.” Seeds that will not be transplanted are sown directly in the “pot” where they will grow. Seed flats and pots may be placed in “trays” that allow watering the plants from the bottom.
The seed packet will tell you how far in advance of the last frost date to sow the seeds. The traditional last frost date in Haywood County is May 15th. Planting too soon results in plants that are too large to transplant easily. Planting too late delays flowering and fruiting. If no planting depth is recommended on the packet, cover the seeds only to their thickness. Don’t cover very small seeds at all. Separate seeds by a half inch or so; this will make transplanting easier. Cover the seed flat with clear plastic to keep the medium from drying out. Place the flat in a tray with enough water in it to cover the holes in the bottom of the container. Put the tray and seed flat in a warm, well-lit place, but not in direct sunlight. Monitor daily to insure enough water is in the tray.
After the seedlings emerge, remove the plastic cover. When the first true leaves (“second leaves”) appear, transplant into pots. Use a plastic knife or pointed craft stick to dig out a seedling, picking it up by the leaves (holding a seedling by the stem may permanently damage it.) Plant in a pot at about the same level it was growing in the seed flat.
Transplant only the number of seedlings you are going to use (with a safety factor built in.) Discard the others, however cruel this may seem, unless you wish to raise plants for your entire community. For example, if I need 25 petunias for a specific flower bed, I’ll plant 35 to 40 seeds, and transplant the best 30 seedlings. After planting outside I keep the 5 extra plants for a few days to make sure all the plants in the ground survive. Then I give the extras away.
You can sow some seeds directly in the pot that the seedling will grow in without transplanting. For example, sow 3 tomato seeds in each pot, then snip off all but the best seedling. Sowing directly into pots is best for hard-to-transplant varieties; check the seed packet for information.
Fertilize every two weeks with half-strength liquid fertilizer. Add water and fertilizer to the tray (instead of pouring on top of the seedlings, which can displace enough medium to expose their roots.) Keep the seedlings in a brightly lit area, but not in direct sunlight.
And that’s all there is to starting seeds indoors!
Cleanliness is essential in your indoor greenhouse. Maintain this area as if it were your kitchen. If you bring plants in from outside to winter in the house, keep them elsewhere, because they are likely sources for insects that can infect your seedlings and be a general nuisance.
To move plants outside, slowly adapt them to outside conditions over a couple of weeks. Give them only filtered shade at first, and gradually allow them to see more and more sunlight. Then they’ll be ready for your beds or outdoor containers. This is called “hardening off.”
Don’t go on an extended vacation. This isn’t a whole lot of work, but it does require at least a couple minutes of attention every day or two. Seedlings allowed to go bone dry will not be happy.
Jim Janke is a Master Gardener Volunteer in Haywood County. For more information call the Haywood County Extension Center at 828.456.3575.