Edmonton Native Plant Society
native plant stewards
by C. Dodd on March 4th, 2011

Early March is a good time to plant native seeds, because a lot of them need to be stratified before they will germinate. Stratification means  providing the seeds with a few weeks of the damp and cold conditions that enable them to geminate in the spring. 
An easy way to do this is let nature do the work. Plant your seeds in pots using a good potting soil, water them from the bottom, then take them outside and carefully bury the pots in the snow on the north side of the house.
Be sure to mark the spot with a flag on a stick so that the pots don't get accidentally shovelled aside.  The alternate freezing and thawing cycles do the work of breaking down the tough seed coat, so that after the snow melts in the spring, the seeds will begin to germinate.

Bruce Bashforth of Bedrock Seedbank likes to cover his pots in plastic, and bury them in an enclosed container to keep the moisture in. I prefer to put my pots in a shallow tray with no cover. Both methods work well, but it is important to bury the pots in the shadiest spot - the one where the snow melts last in your yard. Once the snow has gone, uncover your pots and make sure that they are not standing in water. The soil should be damp but not waterlogged for too long a period. The pots can stay in the shade until the seeds start to germinate. 
Be sure to check every day for moisture levels and signs of germination.

Different species germinate at different times. Some will be up in April; most will emerge some time in May, and a few stragglers won't show until June, just when you have given up on them! I find that some species won't germinate until after the first good spring rain. Some species will be stubborn and won't germinate at all, but if you bury the pots up to the rim in a sheltered spot in the garden, those plants might pop up the next year. Remember to mark them well and water them occasionally during dry weather.

Once the first seeds germinate, move the pot to an area where they can get some morning sun - not too much or the pots will dry out. I usually put mine in shallow trays so that I can water them from the bottom. The trays also prevent the pots from drying out too quickly.

Here's what you need to get planting:
- some large pots, 5 or 6 inches in diameter (12 to 15 cm) - this size gives the seedlings enough room. You can use cell pacs instead of pots if you prefer. Cell pacs are useful because you don't have to go through the hassle of transplanting the tiny seedlings, but they do dry out faster.
- good quality commercial seed starting mix - these are soil-less mixes that contain peat moss. I usually get mine at Apache Seeds, but any garden centre will have it. Make sure the mix is damp before you start. I use the mix because it contains very few weed seeds, and the tiny native seedlings will be easier to recognize when they emerge. This is also the reason that I use a separate pot for each species - it's easier to tell if the emerging seedlings really are the ones you planted if they all look alike.

Fill the pot to about half an inch from the top and gently press the mixture down flat. Sprinkle the seeds over the surface and try your best to space them evenly. This is not an easy thing to do. Remember that a little goes a long way! Don't crowd those seeds. The seedlings will be a lot easier to transplant if they are not packed together in a big clump. If you are worried about poor germination, just plant two pots instead of one. Seeds should be covered very lightly because a lot of species need light to germinate - except for large seeds, such as Alpine Hedysarum, when the general rule is to cover the seed with soil to twice the diameter of the seed.

When you are finished, label the pot with 2 labels (it's amazing how many labels go missing), water it from the bottom and let it sit for a while until the surface is nice and wet. Try to use melted snow water, or tap water that has been standing for a day or two so the chlorine has a chance to evaporate.

When the pots are ready, take them outside to the north side of your house and bury them under the snow. The snow will insulate them and will protect them from extreme temperature fluctuations. Bruce Bashforth of Bedrock Seed Bank taught me this method. Thank you Bruce!

Next month I will write about some of the native flowers and grasses that don't need to be stratified. These species can be planted in April and May.

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