A Guide to Seeding in Fall | Nature's planting time
Jessy Delleman
As summer winds down here on Vancouver Island, in the Pacific Northwest of Canada, the plants are in the process of ripening seeds and releasing them to the care of mother nature and the elements. With the fall rains the seeds will be activated, many will germinate on the spot, the tiny seedlings waiting patiently for the gentle warmth of spring to coax them into further growth. Others will need several months of moist and cool weather to finally unlock them from dormancy.
Teasel (Dipsacus fullonum) and Elecampane (Inula helenium) going to seed in the September garden.
Nature’s time to plant
Most of us think of spring as the prime time to start seeds, and for some varieties, such as tender veggies or non-native plants, this is true. But for the vast majority of plants native to our region, or regions with similar climates, fall can be the best time to plant. Sowing seeds in fall not only gives the plants a huge head start for the next growing season, it is also when Mother Nature plants her seeds.
In fall it is the end of the growing season for a plant, when flowers have faded and developed viable seeds within their ovules. If you follow a plant through the growing season you’ll find they emerge with lush green growth in early spring, and as the weather warms the plants slow their leaf growth and put their energy into making flowers. By late summer and fall, many herbaceous plants have ceased growing and often begin to dye back, with their seeds dry and mature on dry flower stalks.
Motherwort (Leonurus cardiaca) flower stalks with ripened seeds in early August.
These seeds of late summer and fall simply drop to the earth; or are released by the plant into the wind, carried on the fur or in the tummies of local fauna to new locations. Once on the soil, the fall rains moisten them and help to nestle them down into the soil. Through the dormant season into early spring, tiny seedlings will begin to emerge and grow, long before we are able to get into the garden and work the soil.
When you sow seeds in fall, you are leaving the tending up to mother nature. Letting the natural rhythms of nature to have control over when the seeds germinate. Working with this natural rhythm not only removes the effort on our part, but also produces stronger and more adaptable seedlings. Fall seeding results in earlier germination and healthier plants that will be much more drought tolerant and suited to your local climate.
Spring planted seedlings often take some time to get going, and if started indoors may suffer a period of transplant shock when introduced to the elements. Seeds germinated in ideal conditions on the windowsill or greenhouse in spring will have been sheltered from the natural growing conditions of your garden micro-climate such as wind, rain, direct sunlight, or dry, moist, or salt air that may be unique to your area.
The pampered seedlings will be much more vulnerable to stress once introduced to natural conditions, and this may cause a shock to the seedlings which delays or interrupts growth. This is why ‘hardening-off’, or the gradual introduction to the elements, is so important for transplants. Plants seeded outdoors in fall never have to go through this process of indoor-to-outdoor transplant shock or hardening-off.
Fall sown Echinacea (E. purpurea) seedlings emerging in April.
Fall sown seeds germinate when the conditions are right for them outside and they are exposed to the harsher elements of nature from the start, which results in resilient and adaptable plants. These seedlings will grow into strong plants that will be much more adaptable to variable climate, soil, drought conditions, and other seasonal changes.
Seed stratification
Fall is often the easier ~ and more natural ~ time to sow seeds, and for seed varieties needing stratification it is the essential time to plant. Many plants, native to cooler, or temperate climates such as ours in the PNW, need a cold moist period to break dormancy ~ this process if called seed stratification. The stratification period can enhance or unlock the germination potential of many plants. It also protects the plants from germinating too early before the conditions are right for growth in spring time.
It is sometimes possible to mimic the stratification period by refrigerating or freezing pre-moistened seeds for a period of time, but it is much easier and often more successful to simply sow the seeds outdoors and allow nature to do the work. Come spring, seeds that you may have had difficulty germinating in the past will appear above ground as vibrant and sturdy little seedlings as if by magic, guided by the energy of nature.
The ripe seed heads of Wild Carrot (Daucus carrota) and Western Dock (Rumex occidentalis) bent over with the weight of winter frosts.
Seed varieties that need a cold-moist stratification period to break dormancy, and need to be sown in the fall include Agrimony, Ambrosia, Douglas Aster, Meadow Arnica, Balsam Root, Western Buttercup, Narrowleaf Echinacea, Elderberry, Fireweed, Goldenrod, Black Hawthorn, Lomatium, Lobelia, Nodding Onion, Oregon Grape, Stinging Nettle, Pearly Everlasting, Wild Rose, Salal, Blue Vervain, and Wood Betony.
Many other seed varieties aren’t reliant on stratification for germination, but will still benefit greatly from fall sowing. For a complete list of our seed varieties that may be sown in fall here in the PNW please view our Seed Sowing Guide.
Fall seeds for your climate
Choosing which seed varieties can be planted in fall in your region will depend on many factors such as winter hardiness. The seeds will need to be hardy enough to overwinter in your area without damage. Seeds that are native to exotic or warmer climates may not overwinter very easily depending on your region. Examples of seeds that do not overwinter well here in the PNW include Ashwagandha, Basil, Wild Dagga, Dreamroot, Henbane, Sweet Marjoram, Yellow Lavender, Spilanthes, and Virginia Tobacco.
Sometimes the seeds of these more tender varieties will managed to survive our winters, but since they need warmer soil temps to germinate, they will often emerge much too late in the season to take advantage of our short growing season. These late germinators will often bolt (prematurely flower and go to seed) before they have had a chance to put on much green growth. It is recommended to extend the growing season for these varieties by starting them indoors in early spring.
To get an idea of what varieties may do well in your area, start by looking up your hardiness zone. Zones for each seed variety we offer are listed in the seed profiles on our website. Keep in mind that the term ‘hardiness’ only applies to minimum temperatures. It doesn’t take into consideration how moist or dry your climate may be or nuances of air quality, sun exposure, or soil type. As such, it is worthwhile trying out varieties that may be in a zone out of the ranges listed on the hardiness maps.
Fall seeding is not just for perennials. Many annuals and biennials can also be seeded in fall in our climate. Pictured here is an overwintering Mullein (Verbascum thapsus) a biennial.
Timing for fall seed sowing
The timing of your fall seeding will vary from year to year depending on how the season chooses to express itself in any given year. Fall can be a very variable time of year here in the PNW, sometimes we have warm dry and sunny days over 20C well into late October, and other years the fall rains can come as early as the first week of September.
The best time to sow seeds in fall is when the warm and dry weather is securely behind us and we’ve settled comfortably into the cool moist days of fall or early winter. Anytime between mid-October and late-November is an ideal time to sow fall seeds here in the PNW. It is totally fine to plant after frosts, but best to get your seeds out there before it snows.
To get the timing right in your particular region, it helps to get a feel for your local climate through routine observation. A nice ritual is to take a walk around your garden each morning and observe to subtle changes from day to day. Is nature winding down for the season? Are the mornings growing more moist and cool? Walking barefoot each morning can be useful to sync your body up with the subtle changes of the season, and give you an indicator of trending changes in soil temperature.
Sowing outdoors directly in the garden and in containers
There are two options for fall seeding ~ direct seeding or seeding in containers. Both have their advantages and disadvantages. Which method is best will depend on conditions in your region such as winter precipitation, soil quality, and potential competition by weeds and other plants.
If your winters tend to be very wet with higher levels of precipitation, soil drainage will be a consideration when choosing where to plant your seeds in fall. If direct seeding in the garden consider how well the soil drains in that particular area. If soil becomes flooded or boggy in winter, this may cause your seeds to rot before they can sprout. To remedy poor drainage conditions, consider adding an additional layer of compost to improve drainage, or creating raised beds.
Make sure any containers you use to plant your seeds in have drainage holes at the bottom. Keep in mind that clay soil likes to hold on to moisture and can also crust over, making it difficult for the delicate seedlings to break though the soil surface. Instead of using heavy garden soil in your pots, use a mixture of potting mix and mature compost.
Elderberry (Sambucus nigra) fall-seeded into 4” pots.
Aside from improving drainage issues, another advantage of seeding in containers is the reduction of competition of from other plants and seedlings that may be in your garden soil. If direct seeding, you’ll need to clear out a bare patch of garden to make room to plant your fall seeds. Make sure to not disturb the soil too much in this process, just gently tease out any unwanted weeds and loosen the top couple inches of soil in preparation for seeding.
Soil should never be tilled or turned under, doing so destroys the natural soil structure and vibrant ecosystem of microorganisms that live in the soil. The undisturbed natural soil structure keeps the diverse life that lives in the soil ~ earthworms, beetles, beneficial bacteria, fungi ~ happy. This soil life is responsible for aiding with plant communication and keeping nutrients cycling and available on a continuous basis.
Mulching in fall
Healthy soil is built in nature from the top down; from the decomposition of organic matter provided by fallen leaves and herbaceous plants that have died-back for the winter. A balanced woodland ecosystem is naturally self-mulching. Leaves from deciduous trees drift to the earth and blanket the forest floor at the end of each growing season.
Mimicking this natural mulching process in your garden is one of the simplest ways to build soil that is loose and well-drained, rich in nutrients, and supports a healthy ecosystem of microorganisms to help feed and care for your garden plants.
After sowing seeds in fall, either directly in the garden or in pots, it is beneficial to apply a 1-2 inch layer of mulch. The mulch will help to insulate the soil, and stabilize soil temperatures against fluctuations of freezing and thawing that may interfere with germination.
If you live in an area that supports a range of wild foraging fauna ~ such a stellar jays, magpies, squirrels, or chipmunks ~ you may need to put a barrier up to protect your carefully sown fall seeds. A simple way to protect against fall foraging of seeds by wildlife is to lay a sheet of cardboard over your freshly seeded pots or garden area. The cardboard should be removed in early spring well before the seeds begin to emerge.
For general tips on seed starting please also view our previous blog post Starting from Seed | A Beginners Guide.