"Many plants will do this, particularly annuals, such as cleome, garlic chives, peonies, echinacea, rudbeckia, and even cosmos." This allows the seeds to naturally and gradually grow in your garden.
Fall planting will be much easier, so you should aim for getting your seed down late in the season, but before the ground freezes entirely.
Tap Down. Wildflower seeds don't need to be planted in holes; however, they should be tapped down to encourage growth. After you've scattered them over the soil, use the back of a shovel, your hand, or your foot to gently press them into the ground.
By midsummer you should be knee-deep in tomatoes, beans, zucchini, and peppers, so it can be hard to remind yourself to shop for seeds for your next season of vegetable gardening. However, July and August are the best time to get a start on fall and winter food gardening.
Not all flowers are a good candidate for Winter Sowing. Generally, it's best to skip the heat loving plants, like Sunflowers, Zinnias, Celosia, etc. and start those from seed when the weather warms up.
When it's October, people often wonder if it is too late to plant new seed. The good news is if you hurry, seed can still be planted in October with the hope that it will survive the upcoming winter. Although September is the best time, often we can still plant grass seed up to October 15 with good results.
If you live in an area with minimal or no winter frosts (parts of California, Florida, southern Texas or parts of the South West) you can grow wildflowers any time, however, the hottest time of the year is not recommended. It is best to take advantage of the rains and plant in the late fall when the rain begins.
Violas and Pansies
These hardy little flowers not only have gorgeous blooms but can survive almost anything winter has to dish out. Violas and pansies grow best in partial shade but need a minimum of four hours of sunlight a day.
"For the fastest sprouters to flowers, I would recommend sunflowers, calendula, marigolds, nasturtiums, and phlox," she says. "They're not only quick to deliver and total eye candy, but they're each pretty forgiving flowers to get started with.
The seed lies dormant all winter and is ready to sprout the first chance it gets in the spring. Any gardener who has ever cursed an effusive self-seeding plant knows that some seeds do very well when left outside in the cold all winter.
Pansies and Violas (these are the same species including pansy, violet, viola and Johnny jump-up) are a cool season annual that are also cold tolerant. These are the first annuals that can be planted 4-6 weeks before the last frost date and will withstand several degrees below freezing.
Even the planting process is easy. I put down fresh mulch, then sprinkle the Zinnia seeds where I want them. I don't worry about spacing or anything, I just scatter them. When the seeds are down, I sprinkle just a little more mulch over the area for cover.
Zinnias thrive in hot weather and germinate easily from seed. Fall growing conditions are perfect for zinnias because the weather is usually a little dryer. I recommend seeding zinnias by August 15th to enjoy them throughout the fall. They will die out after the first frost.
I plan succession plantings commencing in late May and continue through about the first week of July. This guarantees showy blooms through late September. It is not too late to plant a few zinnia seeds for late summer color that will last until the first frost.
Flowers (Zones 5-10):
October is a great time to plant those fall flowers. There are many varieties that can be planted this fall and start blooming early spring.
Watering Thoroughly, but Not Too Much
Once the seeds have been properly sown and lightly incorporated into the existing soil, water the area thoroughly and leave until next spring. By this time of year, our cool to cold temperatures and short days will help keep the areas moist far longer than in summer.
It can take from two to four weeks for grasses to grow in October, especially if it is a warm-season grass. Cool-season grasses can still germinate and take root in the cooler temperatures of late fall, though you might not see their full potential until spring.