Wildflower Seed: Planting in Fall
Seeds are a miracle of nature, holding the spark of life inside themselves that can stay viable for many years, even decades or centuries if storage conditions are optimum. Seeds are also a very cost-effective way to plant your property with a wide variety of wildflower species, especially when rehabilitating or restoring larger yards and fields.
When To Sow Seeds In Fall (or Winter)
You can mimic mother nature and sow either in the fall or winter, depending on your region. Look at the map shown here to determine where you are and if you are in a cold season or warm season area. In cold season areas wait until November or early December to sow the seeds. You want to have many freezing nights to have cooled the soil sufficiently so that your seeds don't sprout prematurely. Or wait until a big snow is predicted and scatter the seed before the snow flies.
In warm winter climates, wait until the late fall/winter rains begin to sow the seeds. This will provide ideal germinating conditions. Winter sowing is especially helpful in desert climates where the hot weather arrives very quickly in spring and creates hot, dry conditions that can kill tender seedlings.
Identify the Correct Wildflower Planting Time for Your Area
Fall Planting Wildflower Seed in Warmer Climates
In warmer climates, you can take advantage of the rainy season for sowing wildflowers in fall. Your seed will germinate during the most optimal temperatures, rather than the often-times challenging high temperatures of very warm spring or early summer. If you live in a warm climate that still experiences frosts, you'll want to time your planting to be about 60-90 days before the first frost arrives, so your perennial wildflower establish strong root systems before frost. In warm climates, you can also 'winter sow' your wildflowers in January or February, taking advantage of the natural precipitation. Seeds will typically germinate about 2-4 weeks after planting.
Fall/Winter Planting Wildflower Seed in Colder Climates
Make certain that the ground temperatures have cooled enough so that when you sow there is no chance of the seed germinating. It they do, the wildflower shoots will die off with freezing temperatures. In cool climates, make sure ground temps are below 45 degrees. The biggest mistake people make with fall planting in cooler climates is sowing their seed too soon. You can wait and sow over snow in winter as well, as long as the ground has been prepared for seeding.
The Keys to Seeding Success are:
Seeding can be a thrilling experience. But success can take time. Sometimes it will take a couple or three growing seasons to establish a beautiful wildflower meadow, especially when seeding a large area with perennial plants. We often recommend choosing mixtures with annuals included, as you will get quick blooming results while the perennials mature.
- Having realistic expectations
Know your limitations. Be realistic as to what you can afford in terms of time, energy and money. A realistic appraisal may lead you to an incremental approach, planting in stages over several seasons.
- Prepare the area to be seeded to reduce weed competition.
Working the soil to greatly reduce weed competition is key to success. And this will take time. Seeding a big field is not a weekend project.
- Being willing to put in the time and effort to control weeds:
After the seeds have germinated, weed control is the work that will help to establish your new planting.
- Choose the right time of year for your region to sow the seeds:
Fall, just before the rainy season, is the best time for sowing seeds in the desert southwest. In areas that get snowfall, winter seeding can give seeds a leg up in spring. In all areas, you can seed in spring, just as long as the chance for frost has passed.
- Select Plant Species That Are Regionally Appropriate
Use quality seeds of plant species that are well acclimated to your region, climate and soil type. This will greatly enhance the long-term beauty of your seeding efforts.
Understand Your Planting Site
It's essential that you know at least a few basic details of your plant site.
- Determine your soil type. It is especially important to know if you have clay or sandy soil. Other soil types are generally suitable for wide range of species. But clay and sandy soils will necessitate choosing wildflower species that prefer them.
- Know your directions. Where's north? This will help you identify shady or sunny areas around trees and buildings.
- Find out if there is a slope to your property and know the direction of the slope. A north-facing slope will have colder soils that a south facing slope and may require a different seed mix in very cold climates.
- Identify trees and buildings that cast shade onto the planting site. Shade is not a good growing condition for sun-loving plants. You will need a different seed mix for shady areas.
- Measure and calculate the square footage of the area to be seeded. This is essential for determining how much seed will be needed.
Understand the Condition and Existing Vegetation On the Planting Site
This is very important to the long-term success of your seeding project.
- If you are seeding into what used to be a lawn or recently cultivated crop field, the time needed to prepare the site for planting is much less than seeding an old overgrown farm field choked with weeds and shrubs or other invasive species.
- If your area to be seeded has a lot of desirable species already on site, you may just need to prepare small pockets scattered around the site to seed while leaving the established plants undisturbed.
Choose Native Plant Seed Mixes For Best Long-Term Success
In general, it's best to choose native species when deciding on a seed mix. Having some Old World annuals in the mix is OK, because they will provide colorful flowers the first couple of years and then give way to perennial native plants that take longer to establish themselves.
Preparing the Planting Site
If the area to be seeded is a lawn or weedy patch, then it's important to get rid of the lawn grasses or weeds by either:
- Smothering: This can be done one of two ways. If you want to improve soil quality or bring life back to compacted or damaged soils, covering the area with corrugated cardboard and newspaper. Then bury with a 6-to-8-inch layer of fine-textured wood chips or compost. Water every couple of weeks in hot dry weather. And in 4 to 8 months, all the weeds/lawn grass will be dead and the area ready to rototill. Alternately, you can cover the area with heavyweight tarps to create dark, moist conditions that will kill and rot the weeds/lawn grass. Note that this will not greatly improve the soil's tilth and nutrient content.
- Solarizing: Covering the lawn grass or weeds with clear plastic and burying the edges for 6 to 8 weeks during the heat of late spring/summer will cook them to death. Afterward, the area should be rototilled and raked to remove all the dead plant debris.
- Careful use of herbicides: if time is of the essence. the judicious use of systemic herbicides is your best bet. Use protective gloves and clothing. And remember, a healthy living soil can break down herbicides when used sparingly. Rototill the area after the lawn grass/weeds are completely dead,
Once the existing plants have been killed off, rototilling should be done to prepare the soil as a seedbed. Repeat several times to encourage weed seed germination and eliminate dormant weed seeds that sprout after being brought to the surface by rototilling.
Create a Nice Seed Bed
When you're ready to seed, give the area the last rototilling about 2 to 3 inches deep and rake with a stiff bow rake to break up the dirt clods and create a smooth, even-textured soil surface.
Spread The Seeds Evenly
Unless you’re seeding a very large area, it's best to scatter your seeds by hand. I don't like to use a hand-cranked whirly bird seeder unless the seeds are all of a similar size. If the seed mix contains large and small seeds, the cyclone seeder (whirlybird) may not throw out the seeds evenly.
- I prefer to mix my seeds into slightly moist sand (bagged playground sand) which is used as a filler to more evenly distribute the seeds.
- It's also essential for larger areas that you divide the planting area and the seed mix into smaller parts to more evenly spread the seeds. If you're seeding 1,000 sq. ft., divide the area into four even parts and divide the seed needed to cover that area into the same number of portions.
- Take a 4-gallon plastic bucket and fill it with one part seed to 10 to 15 parts sand; a cup of seed to 10 or 15 cups of sand is a good ratio. And be sure to mix in a couple of tablespoons of Plant Success Granular mycorrhizal Spores into the sand/seed mix to improve seed germination and seedling vigor.
Firm the Seeds into the Soil
Once the seeds have been sown, you need to press the seeds into the soil to ensure good germination. This is better than trying to cover the seeds with soil. Use a sod roller, a small 2 ft. x 2 ft. piece of plywood or 2 x 8-inch board that you can stand on to firm the soil around the seeds.
If you’ve sown in winter and get snow cover, firming the soil isn't needed as the freeze/thaw cycle during the winter and spring will push the seeds into the soil.
Typically, fall and winter plantings don’t need to be watered. But it can be helpful to have some sprinklers available to irrigate the seedlings beginning in mid-spring if conditions are dry. If dry conditions continue into the summer, turn on the sprinklers to put down about 1/2 inch of water once every one to two weeks. Sandy soils may need a bit more frequent watering when it gets hot and dry more often.
It's essential that weeds be controlled so that they don't smother out the desirable seedlings. This can be done by hand weeding (for small areas) or mowing (larger areas where hand weeding isn't practical).
- Hand Weeding. Be sure you can identify seedlings of the seeds you sowed so that you don't weed them out by accident. It's better to cut the weeds off just below the soil line with a weed fork or a Hori Hori knife (or similar implement) instead of pulling the weeds. Pulling weeds disturbs the soil and actually creates a new seedbed for existing seeds in the soil, or seeds that blow into the area, to germinate.
- Mowing. Mowing large seeded areas during the growing season is a great option for helping your seedlings to establish themselves by limiting competition from weeds. You can use a lawn mower or string trimmer. Set the mower deck to a height of 4 to 5 inches and mow when the weeds reach about 8 inches tall. Repeat as needed through the first growing season. If weeds persist during the second year, additional mowing will be helpful.
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