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rowing native plants from seeds
Sowing next year's garden
by Sandy Garland
AS THE GROWING SEASON comes to an end, we're already thinking about next year's plants. Those of us who are interested in propagating native plants have been busy collecting seed from the best varieties in our Backyard Garden.
Because these species are native to our area, they are accustomed to a dormant period during which the temperature is very low. Many will not grow in the spring unless they do go through this cold period and the chemical changes that it causes in the seeds.
The easiest way to handle the seeds is to simply throw them into the garden in the fall and let them overwinter naturally. However, we have had poor results with this method. Instead, we mix the seeds with a small amount of damp vermiculite and store them in the refrigerator (cold but not freezing) over the winter.
In mid-February to March, we remove the seeds from the cold, and spread them (vermiculite and all) over a half-inch layer of vermiculite in styrofoam trays. We cover the trays with plastic wrap to keep moisture in. A few species need light to germinate; those trays are placed near a window.
Within the next few weeks, the seeds will begin to sprout. As soon as they have 2 leaves, we transplant them into potting soil in cells (the sort of seed-starter kit you can buy at a garden or hardware store). They stay inside until the weather starts to warm up.
Providing enough light at this stage is often difficult unless you use an artificial source. On warm afternoons in April, it's safe to put the flats outside, but not in direct sunlight. This "hardening off" process can be time-consuming.
By mid-May, the plants can be left outside all the time, but again, not in direct sunlight. When they are about 2" tall, we transplant them again, this time into 4" pots.
Many perennials will not be robust enough to plant out in your garden until their second year. Several, like Trilliums, take 7 years. No wonder native plants are difficult to find in commercial nurseries!
Plants that we've grown successfully from seed:
Flat-topped Aster, Aster umbellatus
Field Pussy-toes, Antennaria neglecta
Native Flax, Linum perenne var. lewisii
Beardtongue, Penstemon digitalis
Thimbleweed, Anemone virginiana
Cup Plant, Silphium perfoliatum
Swamp Milkweed, Asclepias incarnata
White Snakeroot, Eupatorium rugosum
Clematis, Clematis virginiana
Culver's Root, Veronicastrum virginicum
Blue-eyed grass Sisyrinchium sp.
Balsam Ragwort Senecio pauperculus
Pearly Everlasting Anaphalis margaritacea
Prairie Smoke Geum triflorum
White Turtlehead Chelone glabra
Blue-stemmed Goldenrod Solidago caesia
by David Tomlinson, O.A.L.A. (E)
I thought your volunteers might be interested in the outdoor method of seed sowing I have successfully used over the last 20+ years. With this method I have germinated and grown on hundreds of species of temperate perennial wild flowers, trees and shrubs in Merlin's Hollow, my garden in Aurora.
Under normal conditions, you will get above average results if you carefully follow the instructions below. I have used them successfully to grow a wide range of temperate plants over a period of 25 years.
- Collect limited amounts of seed from common wild plants as soon as they are ripe, before natural distribution occurs. This can be tricky, as seeds that are collected too early will be too immature to germinate, and if they are left too late, they will have already been shed. Some species have a short period between becoming ripe and scattering. Experience will quickly teach you which plants hang on to their seeds and which distribute it as soon as possible.
- Most woodland wild flowers' seeds (like trillium, trout lily, hepatica, and Jack in the Pulpit) should be sown as soon as they are collected. Before sowing, remove any soft pulp. Seeds that are sown fresh normally germinate well, but dried out seeds will take several years to germinate.
- Wildflower seeds should be thoroughly dried in a sunny room in brown paper bags. When the seeds are bone dry, remove the chaff from the seeds and store them in an envelope, then in a Tupperware container or sealed plastic bag until you are ready to sow them. Store-bought seeds don't need to be dried and separated before putting them in your freezer.
- In late November, buy a bag of Promix or similar sterilized soil-less mix. Soak the mix in its bag with some warm water and leave it standing for at least 24 hours. Poke two small holes (about the size of a pencil) in the bottom of the bag to allow water to drain slowly. Leave the mix in the bag until all the surplus water has drained and the mix is moist but not waterlogged.
- For each seed, fill a 4" pot (or similar container with drainage holes) to within 1/2" of the top of the pot, patting the mix down lightly. For wildflower seeds, it is advantageous to mix some woodland leaf soil in with the Promix before sowing.
- Write a label for each of your seeds and stick them in the pots, then sow each seed on the surface of the mix and cover it in mix by about twice its diameter by shaking the mix through a sieve. Very fine seeds can be sown uncovered.
- Water the seeds well using a hand mister or watering can with a fine spray head. Leave the pots indoors for no more than 2 days, then place them outside behind a north (preferably) or east wall, or in another very well-shaded location. Keep the seeds moist until the mix freezes. Do not cover the pots with polythene or other material: allow the snow to drift in on top of them.
- When the snow thaws in early spring, check your seeds every 2-3 days for germination, and remove any germinated seeds to a sunnier location. Shade plants can remain behind the north wall. Keep the pots regularly watered before and after germination.
- Guard against damage from slugs and mice: seeds you think haven't germinated may have been eaten already.
- In late May, move the ungerminated seeds to a sunny location and keep them moist. Different seeds germinate at different times, so if germination doesn't occur the first year, put the pots back in the shade for a second or third year; some of ours germinated on the compost heap where we had discarded them.
- When the seedlings are large enough (with 2 or 3 leaves), they can be repotted individually to 21/2" x 21/2" x 31/2" pots and grown until they are large enough to be planted in beds.
- Excellent results can be obtained if the seedlings are planted in a nursery bed in rows spaced a trowel length apart. If planted before early July, they will be large, well established plants by the following spring. Slow growing woodland species will need more time in the nursery beds before they are large enough to survive in the wild.
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