Seeds: What’s the Story?
- jessica36732
- 11 minutes ago
- 6 min read
By Liz Deleeuw
Editor’s Note (by Patsy Cotterill): Fall is the time when ENPS members start cleaning and packaging the seeds that have been collected throughout the season. I was once asked “What is the best time to collect seeds?”, the questioner obviously looking for me to name a date, but I said “When they are ripe.” This isn’t entirely true. The seeds of some species can be taken off the parent plant before they are ripe and they will subsequently ripen. (Beaked hazelnut, for instance; best to collect the nuts before the squirrels get to them!) However, in most instances, collecting when the seed is ripe is the best bet and requires careful observation of the plant’s development. Another thing to bear in mind is that many plants, particularly woody but also herbaceous plants, have mast years, years in which they produce abundant seed, but also years in which they produce very little or almost none. This too demands observation and an understanding of the plants’ cycles.
For those who don’t have time to be plant watchers or seed gatherers, purchase of native plant seeds is the answer. ENPS sells packaged seeds at sales events and in various garden stores. (We are happy to announce that Apache Seeds is now selling our seeds throughout the year.) Purchased seeds can be stored at home for spring sowing, or processed earlier in the year, as indicated below.
In the following article, Liz Deleeuw, the ENPS’ growing expert, describes what to do with those seeds you have purchased, or have harvested from your own garden-grown native plants. You can plant them outside in the fall (or even winter), or you can wait until spring is imminent.
If you do decide to wait until spring, to plant outdoors, you should be aware which species require a pre-treatment known as “cold, moist stratification” for germination. This will be indicated on the packet or in the literature. This pre-treatment occurs automatically for seeds that overwinter outdoors in a natural setting, but can be accomplished artificially indoors as well. (Any species which do not need this weeks’ long exposure to cold and moisture can be kept dry and sown directly into the ground/pots in the spring.)
Liz notes that in an earlier article she said that simply stratifying in cold (but not moist) conditions was possible, but she was corrected by a reader who said that “stratification”, by definition, involves the use of moisture. However, Judith Golub, who was also a grower, found that many species that were thought to require stratification would, in fact, germinate after being stored dry (not wet) in the fridge for a period of time. For long-term (multi-year) storage, the experts recommend that seeds be stored dry in the freezer at -18°C.
On the ENPS website, we will publish a list of species we commonly grow that don’t need stratification, and we will endeavour to keep it updated according to what we have in stock.
How To Stratify Native Seeds
Many native forbs, sedges, and some grasses, require stratification for germination. Stratification alerts the seed that it is time to germinate, through changes in its conditions. In nature (at least in the Edmonton area), the spring brings gradual thawing of the soil, and the presence of moisture lets the seeds know it is safe to germinate. This typically involves a cold, moist stratification. (A few species, like blue-eyed grass, are more particular and may need a warm, moist period as well.) Stratification can also be achieved indoors as described below.
Fall Dormant Seeding In Situ
It is possible to sow seeds directly into the garden in the fall. The seeds will naturally be stratified as the spring comes. If you do choose to plant directly into the garden be sure to mark the planting area well. Also be sure to know what the seedlings will look like, and be ready to protect them from encroaching weeds. This is not the method we usually recommend for starting seedlings.
Fall/Winter Dormant Seeding in Pots
Instead of sowing directly into the soil, we recommend that you sow your seeds into pots filled with potting soil or mix in late fall. Alternatively, this sowing in pots can be done as late as February. In either case make sure these outside pots are covered by snow, and are in a spot that will thaw evenly in the spring (hence, out of direct sunlight). You must also make sure the pots are kept moist after the snow is gone. With this method, the seedlings will not have to compete with garden weeds, and can grow in the pot until they are ready to be put into the garden. Many native plants spend the first season developing their root structure so the plants generally do not get that large very quickly. In my experience there is less germination with this method than with the indoor stratification that is described next, but it is worth a try.
Cold, Moist Stratification Indoors
Another method is to sow the seeds after they have first been subject to an artificial cold, moist stratification in the fridge. To accomplish this, start with a mixture of equal portions of sand and peat moss (do not use soil). Use five parts of that mixture to approximately one part of seed. Mix the seed in well and place everything in a baggie, adding just enough water to dampen the mix. Do not over moisten it. (You can use more of the sand/peat moss mix if you would like more spacing between seedlings when they come up.)
Place the baggie in the fridge for six weeks. At the end of the six weeks (OR if the seeds start sprouting earlier than that), it is time to pot them up. (If only a few have sprouted, pot them up and return the rest to the fridge.) Spread the mixture on top of pots filled with a growing medium (seedling mix) that does NOT contain soil. This helps prevent the seedlings “damping off” (getting a fungal disease that causes the stem and the roots of the seedlings to rot). Cover the seeds lightly (with the growing medium) according to seed size, if necessary. Place the pot where it gets light either from a window or a grow light. Keep it moist, but not wet, until the seeds germinate. Some growers run a fan occasionally to create a breeze, which helps to strengthen the stems and prevent rot. I run a fan with a timer.
With this method you will get a pot with a lot of seedlings in it. Once the seedlings are developed, they can be “pricked out” into smaller pots to grow on. This simply means carefully separating the individual plants and moving them into their own pot filled with soil or growing medium. The plants can then be grown either inside or outside, if the weather is suitable and the risk of frost is gone.
Tender plants started inside should be “hardened off,” which allows the plant to gradually get used to the outside conditions. This involves putting the plants outside during the day in dappled shade but bringing them in for the colder nights. Gradually move them into more sun and, when night temperatures allow, leave them totally outside for a few days in full sun. When you judge they are robust enough to withstand the transplant, plant them in your chosen location in your garden.
Editor’s Postscript:
ENPS has just received the newsletter of the North American Native Plant Society, based in Toronto. It draws attention to the Indoor Native Seed Stratification Guide, written by Ryan Godfrey, accessed from the Growing Native Plants tab on the NANPS website: https://nanps.org/96358-2/
Godfrey recommends simply placing the seeds on a wet paper towel folded over before placing in the plastic bag which is then sealed and left in the fridge (1-4°C) for six weeks. This may be easier than using a seed mix. He also recommends checking on the seeds every so often (easier to do as the towel will be transparent) for signs of mold, and removing it promptly or discarding the seeds if they are badly infected. Checking will also reveal any premature germination, in which case the seeds will need to be sown, if possible. He suggests the seeds should be allowed to acclimatize to room temperature for 24 hours after removal from the fridge and before sowing, still within the plastic bag to avoid exposure to air and mold spores.
