Growing from seed
Seed stratification
Many tree, shrub and perennial seeds will not sprout until they have been through a winter. Stratification is giving them that winter, outside or in your fridge.
Outside, in the fall
The simplest way. Sow the seed in a labelled pot or bed in the fall and let winter do the work. Cover it against squirrels and mice.
In the fridge, over winter
More control, and you can see what the seed is doing. This is how we start most of our own seed. The steps are below.
Best option is to plant them in the fall, if not just use your fridge.From our field notes
The fridge method
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Soak overnightSoak the seed in water, then drain it.
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Add a damp mediumPeat moss, sand, vermiculite, coco coir or seed starting mix. Use about two to four times the volume of the seed. It only needs to be damp, not wet. It holds the moisture even and keeps the seeds apart.
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Bag it and label itWrite the kind of seed, the date, and how many months it needs.
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Into the fridgeKeep it at normal fridge temperature, cold but above freezing. Not the freezer. A root cellar works too. Leave it for the time on the seed listing.
What it looks like
The seed is mixed right into the damp medium, not sitting on top of it.
When to start
Count back from when you want to sow. For sowing in April:
Warm, room temperature Cold, in the fridge Sow
Warm, then cold
Some seeds need a warm spell before the cold one. Viburnums such as nannyberry and highbush cranberry are like this, and plums often are. Keep the same damp bag at room temperature for the warm period, then move it to the fridge for the cold period.
With nannyberry and highbush cranberry, the seed often puts out a root during the warm stage and then stops. That pause is normal. The shoot comes after the seed has had its cold period.
These take the longest. Seed started in fall can be ready to sow in spring. Seed started in spring waits until the spring after.
How to tell it is ready
Check the bag every week or so toward the end. When seeds start to sprout in the bag, they are ready. Sow them then, and handle the new roots gently.
One way to know your seed is ready is when any of them start to sprout in the bag, easier to plant at this stage.From our field notes
If nothing happens
Some seed has deep dormancy and needs a second winter. Do not throw the bag out. Keep it damp and give it another cold period.
the first year maybe 40% germinated, this spring the other 60%. this is why I like to keep large seeds in the bag until they start to germinateFrom our field notes, Canada wild plum
What can go wrong
- Too wet. The medium should be damp, not soaking.
- Frozen solid. Seed needs a long time cold but above freezing. Small raised beds above ground can freeze too hard.
- Mice and squirrels. Cover seed sown outside.
- Late frost. New seedlings are tender. Protect them the first spring.
- One basket. Split a seed lot between the fridge and the ground, so one problem does not take all of it.
Other methods
Damp paper towel
Instead of peat or sand, spread the seed on a damp paper towel inside a bag. You can see every seed, so it is easy to spot the first roots. Norman Deno tested thousands of kinds of seed this way, moving them between cold and warm every three months. We use it for some seed, such as grapes.
Scarifying hard seed
Some seed has a coat so hard that water cannot get in. Nicking the coat, or rubbing it with sandpaper just before sowing, lets it take up water. A hot water soak does the same job for some kinds. Where one of our seeds needs this, its listing says so.
Winter sowing in jugs
Sow into a clear jug or covered container with drainage holes and the cap left off, and set it outside where it gets snowed on but is out of the wind. It is fall sowing with some protection, and it suits hardy perennials and wildflowers.
What our seeds need
The exact time for each kind is on its seed listing.
No stratification 22 kinds
American Elm · Amur Maackia · Blanketflower · Bur Oak · Caragana · Goji Berry · Hollyhock · Jacob's Ladder · Lemon Bergamot · Norway Spruce · Pale Purple Coneflower · Purple Coneflower · Red Clover · Scots Pine · White Clover · White Yarrow · Wild Bergamot · Wild Blue Flax · Wild Chives · Wild Licorice · Yellow Bedstraw · Yellow Sweet Clover
Up to 1 month cold 20 kinds
Blue Vervain · Chinese Lantern · Common Milkweed · Dwarf Milkweed · European Columbine · Fernleaf Yarrow · French Thyme · Giant Hyssop · Harebell · Hollyhock Mallow · Lilac Beardtongue · Maral Root · Maximilian Sunflower · Mongolian Spruce · Mugo Pine · Queen Anne's Lace · Red Yarrow · White Spruce · Wild Pansy · Wild Strawberry
2 to 3 months cold 45 kinds
Alpine Currant · Aurora Haskap · Black Eyed Susan · Box Elder · Boyne Raspberry · Callery Pear · Cherry Prinsepia · Common Ninebark · Cutleaf Coneflower · Dahurian Larch · Downy Arrowwood · Engelmann Spruce · Goldenrod · Good King Henry · Hackberry · Heart Leaved Alexander · Himalayan Mayapple · Hops · Hyssop · Joe Pye Weed · Meadow Blazingstar · Mountain Maple · Narrow Leaved Coneflower · Northline Saskatoon · Osage Orange · Ponderosa Pine · Prairie Crocus · Prairie Smoke · Pussytoes · Red Birch · Red Elderberry · Red Fruited Silver Buffaloberry · Redosier Dogwood · Smooth Sumac · Staghorn Sumac · Striped Maple · Thiessen Saskatoon · Upright Prairie Coneflower · Ussurian Pear · Weeping Birch · Wild American Black Currant · Wild Cucumber · Wild Raspberry · Wild Sea Buckthorn · Yellow Fruited Silver Buffaloberry
4 months cold or more 26 kinds
American Mountain Ash · Amur Maple · Black Currant · Black Walnut · Bunchberry · Butternut · European Mountain Ash · Frontenac Grape · Garrington Chokecherry · Hinnomaki Red Gooseberry · Lee Red Chokecherry · Northern White Cedar · Ohio Buckeye · Oxheart Chokecherry · Purple Gooseberry · Red Currant · Riverbank Grape · Rocky Mountain Iris · Schubert Chokecherry · Valiant Grape · Wax Currant · Wild American Hazelnut · Wild Black Chokecherry · Wild Sarsaparilla · Wild Saskatoon · Woods' Rose
Warm, then cold 25 kinds
American Black Elderberry · American Bladdernut · American Wild Plum · Arrowwood Viburnum · Blue Elderberry · Canada Wild Plum · Chinese Viburnum · Common Juniper · Downy Hawthorn · Early Blooming Lilac · Evans Cherry · Green Ash · Hedge Cotoneaster · Indian Currant · Linden Viburnum · Manchurian Apricot · Nanking Cherry · Native Hawthorn · Pembina Plum · Pin Cherry · Romance Series Sour Cherry · Seedling Plum · Stinging Nettle · Wild Raisin · Winterberry
