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Perennials Can be Sown from Seed

Updated: Apr 13, 2021

If you are saving seeds from your own or someone else’s garden keep in mind that seeds from hybrid plants do not come true. It is like expecting the cross breed of a poodle and a greyhound grandchild to look anything like either of the hybrid parents. Genetic marbles do sort out in the third generation into all sorts of unusual or even bizarre combinations. Sometimes you will stumble upon a new and uniquely worthwhile plant, but more often you will not. If you are curious, try growing seeds from hybrid plants; with luck, you may come up with a unique plant. If you keep growing and sowing seeds of your new variety and selecting for the characteristics you want and discarding the rest, in 6-8 plant generations you will develop your own open-pollinating, true to type new strain of perennial. For example, Columbines are very promiscuous and will hybridize with any other Columbine. Unusual plants are the result.

Sometimes you do not have to even plant perennial seeds. Mother Nature will do the job for you. A purple coneflower, columbine, black-eyed Susan, and others will ripen seeds and self-sow nearby. Make sure to stop deadheading these plants and let the seeds ripen and fall. Give these seeds a chance to grow by pushing aside mulch in the fall and leaving some bare ground for them to sprout in. You can even collect seeds of spring blooming bulbs like scillas and snowdrops, and create whole rivers of springtime bloom.

Some seeds, especially those of our wildflowers, require a special treatment in order to sprout. Many kinds of seeds which drop in the fall must undergo periods of cold and thawing to break down chemicals which keep them from sprouting too soon. Cold treatment (called stratification) to mimic being outdoors can be done by adding moist sand or sphagnum moss to the seeds, and storing the mix in plastic bags in the refrigerator (34-41 degrees F). Cold treatment may require 30, 60, 90 days or longer in your refrigerator. Do not freeze. Check the bags weekly and plant the seeds if you see germination. Otherwise take them out after the recommended time of stratification and plant them in pots or outside. You may have to investigate the sprouting requirements of your seeds. Hopefully, the package label will provide all the information you need. If it is too late for a needed cold treatment, you could always plant these seeds outdoors in a protected spot next autumn. Some seeds need light to germinate. Others need to be covered with soil.

Sometimes all you need to start germination is to soak the seeds overnight. Other seeds have thick coats that need to be nicked with a knife, toenail clipper, or by rubbing between coarse sandpaper or shaking seeds in a jar lined with coarse sandpaper. Be careful not to damage the seed or remove the protective seed coat; all you need is a small break in the covering for water to enter and sprouting to start.

When you grow the seeds indoors, germination can take a month or longer and not all seeds may sprout at once. Some seeds may not sprout at all--in many cases 50% germination is considered great. Do not lose patience, as some perennials are frustratingly slow to sprout; some of the more difficult woodland species require 2 cold-freeze-warm cycles before they will sprout.

February is an ideal time to start perennials indoors for your garden. Start with a sterile, well-draining, soil-less starting mix. It may be store-bought or a home-made mix (Google “seed starting mix recipe site: edu”). Typical garden soil is just too dense; it packs readily, blocking out air and preventing proper drainage. A one-time investment in a special heating mat will warm the soil and help seed germination. Perform any recommended pre-treatments on the seed. Carefully dampen the mix. Plant seeds at the proper depth. Label the tray with the plant name and date planted. Cover the tray or pot with plastic wrap and uncover when seeds start germinating. Let the soil dry out a bit if there is too much condensation. Carefully water the young plants. Too much water encourages root rot and damping off diseases. Some growers use a small fan to provide air circulation and prevent over-moist conditions. You may have to water more frequently if you use a fan. A typical shop light suspended 1-2 inches above the young plants will provide adequate light. Keep the light on for only 12-16 hours a day. Water with a weak (25% of container label recommendation) liquid fertilizer solution, gradually increasing the fertilizer strength as the plants grow. Attend to your seedlings every day; problems can happen rapidly and need to be addressed.

As the plants grow, upshift them to larger individual pots. When danger of frost is passed, toughen up (“harden off”) your plants by gradually increasing the length of outside exposure. Start by placing them in a shaded protected area for an hour or two at first. Gradually, over a two week period, increase the sun exposure and time period. Your plants are now ready to plant in the garden.

Taproots on lupine and poppies make transplanting difficult, and these are best planted directly in the garden. Good perennials to start indoors include Alliums, Anise Hyssop, Catmint, Columbine, Coreopsis, Delphiniums, Dianthus, Gailardia, Primrose, Rudbeckia, Shasta Daisy, and Yarrow. Jennifer and I are growing the Coneflower varieties, ‘Pow-Wow Wildberry’ and ‘Magnus Superior’ from seed, as well as many other perennials. I hope your head is now full of great ideas for sowing perennial seed.

Happy Gardening, Joe Baltrukonis


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