Late fall and early winter is a perfect time to cold seed flowers or create your pollinator garden-- until snow makes it impractical! The timing mimics Mother Nature’s seed scattering, as wildflowers naturally drop their seeds in fall. This provides the benefits of freezing and thawing, a process called stratification, which breaks down any dormancy, improving the germination rate. Cold seeding also helps crack open hard outer seed cases and provides the extra moisture that winter often delivers. Flowers to consider seeding include:
Cold seeding is a good choice if you live in an area that has a shorter growing season and the ground freezes for more than 60 days. You’ll get a jump start on spring growth as the seeds will germ when the time is right, providing you with a color display 2-4 weeks earlier than with spring planting.
When to plant?
Be sure that it’s truly cold enough before planting in the fall. The most common mistake when fall planting is planting too soon. Remember that the soil cools down gradually, much like a large body of water. You want to make sure the seeds stay dormant over the winter with no chance for fall germination or they will simply winter kill.
Prepare the planting area before it freezes down completely, getting rid of weeds, grasses, or the past season’s flowers, roots and all! Old grass roots are especially important — be sure to remove them or they'll grow back along with your new wildflower plants. This is your opportunity to remove any plants that will compete with your wildflowers before sowing those precious seeds. Make plenty of room for your wildflowers to sprout and thrive! The better you prep the stronger your seeds will shoot without competing plants to ‘steal’ nutrients and water. This will ensure lower maintenance enjoyment of your new flowerbed and thick, lush growth.
Now that you have the timing and preparation work down, decide if you would like a ‘patchwork’ effect, with certain flowers planted in designated spaces or if you prefer a ‘wildflower meadow’ effect with multiple flowers interspersed in the same space. This will impact the next important consideration-- the application rate – meaning how much seed should be placed in a given space.
Application rate and dispersion
It may be tempting to throw in some extra seed to get more growth and more blooms. However, this will pack young seedlings so tight together that they strangle one another out, leaving you with fewer flowers. The surviving flowers are often tall and spindly as they struggle to reach for the sun and their fragile stems are not able to withstand wind and rain.
Follow spacing instructions on the packets. If you are planting very small seeded flowers, you might consider combining the tiny seeds with dry ‘sandbox’ sand to make dispersion more even. Light-colored sand will allow you to see exactly where your seed landed, helping eliminate bare or overplanted spots.
Another option is to divide your seed into two equal parts. Plant one portion of the seed over your planting area in a north-to-south direction. Next, take the remaining portion, and sow those seeds in an east-to-west direction. You could use the sand dispersion method with this spreading technique as well.
If working with a very small amount of seed you can use a ‘pinch’ method, taking a pinch at a time and gently rolling them out from between your fingers, taking care not to overcrowd them in one spot. Again, combining the seed with sand may help.
The final step is to compress your seed into the soil, to make good seed-to-soil contact. This step ensures the flow of nutrients and moisture for germination in the spring, helps to anchor your seed, and prevents wind, water, and natural occurrences from displacing your seed.
The size of your planting will affect how you go about compressing your seeds into the soil:
- For medium-sized plantings, lay a piece of cardboard or plywood over the soil and walk on it, covering the entire area. Plywood works well because it will more evenly distribute your weight across the soil, providing a more even compression effect. When you lift the cardboard or plywood, make sure to brush off any sand or seed that sticks back into the flowerbed.
- For small-sized patches, you can just use your hands to pat and compress or use your feet to walk and compress seeds into the soil. Make sure to inspect your shoes or feet for seed before leaving the bed.
Check the seed packet instructions to decide whether to cover the seed. Some flower seeds are very tiny, and many require light to germinate. Unlike most vegetable seeds, which are typically buried in the soil, many flower and wildflower seeds are scattered on top of the soil and left exposed. So check your planting instructions for each of the varieties you plant.
If you are planting on a slope or steep bank that is subject to erosion, wind or rain can carry your seeds downhill or bunch them all together. To reduce this risk you may need to cover your seeds with a light covering of chopped straw. Again, if your seeds require light to germinate, only sprinkle a feathery dusting to allow for light.
Germination and weeding
In the spring your seeds will germinate when the soil reaches about 55 degrees F. As your seedlings germinate you will find yourself asking, “Which are flowers and which are weeds?”
Our best advice is to adopt an attitude of patience. Do not ‘weed’ until you are sure you know what you are removing!
One helpful strategy is to take an egg carton and plant 3-4 seeds in a cell, label with each of your varieties, so you can identify your plants as they grow. Nestle the egg carton sampler in or next to your flowerbed, so they grow at the same time as the bed. These are real live seedling identification helps. And you can transplant them later in the spring to fill in where needed!
When in doubt - do not pull your plants! Give the seedlings some time to grow; you may find that they were flowers after all!
Wishing you bunches of flowers in your garden next spring!
Our best to you,
Theresa & Dan