Are you thinking about next year’s garden already? We’ve talked about a lot of autumn gardening ideas lately: what seeds to sow in October for a spring harvest, how to extend the growing season, fall cleanup, and using leaves as mulch. Now let’s discuss seeds that you can sow in autumn for next year.
Many perennial plants, especially native wildflowers, shrubs, and trees, need the winter weather cycles to germinate. The changing temperatures help the seeds to break dormancy and to break through the hard outer coating. The home gardener has a few options: cold stratify the seeds early to plant in the spring, or get a head start by planting in the late fall or winter.
Early Planting Strategies for Perennials
Depending on where you live, fall or winter seeding could work. To decide your strategy, consider how cold your winters are, frost, and hard freezes. If you’re not quite sure about soil temperatures, get to know your local microclimate. Your local agricultural extension or local gardening clubs are both great places to start.
Cold Winter Climates
It’s better to wait a little longer than to plant too soon if you live in an area that has very cold winters. If this is your area, fall planting should be delayed until the average ground temperature is around 45 degrees Fahrenheit. A good rule of thumb here is usually after two cold freezes. This prevents the seeds from sprouting too soon and then freezing and dying off.
If your falls and winters are relatively warm and you do not typically get frost, you can use the rainy season of fall and winter to germinate your plants. Your perennials will germinate at the right temperature and get a head start on establishing roots.
If you live in a warm climate but you still get occasional frosts, you can use strategies to protect your seedlings from mild frost like covering the plants. If you expect hard freezes where the soil will become frozen, then try to get your seed in the ground at least 2 months before the first frost. This gives perennials like wildflowers a chance to start developing roots and prevents the young seedlings from dying off. If you have missed that window already, aim for winter sowing in January or February.
Starting Perennials Outdoors In Containers
If you plant early, you don’t have to choose the final resting location immediately. If you aren’t sure where you’re going to put the seeds in spring, you can always start your seeds in soil blocks, seed trays, a milk jug, or other containers. This gives you the best of both worlds: you can protect your plants from early germination and subsequent frost. It also means your plants will be adapted to the outdoor setting without any need for hardening off, but you’ll have a bit more control over plant spacing, without worrying about thinning or remembering what you placed where.
Preparing the Soil
If you’re going to directly sow your wildflowers or other perennial plants, don’t make the mistake of scattering seeds onto unprepared soil and hoping something will pop up next year. While many wildflowers require surface sowing and won't germinate if buried too deeply, proper soil preparation is essential. Otherwise, seeds can get washed away, become food for animals, or fail to thrive. To prepare your soil, you need to clear the area of competition and loosen the soil. This can be done with hand tools or a rototiller. Many wildflowers can thrive in poor soil as long as it drains well and there’s no competition.
Label Your Seeds
As you plant, it’s important to know what is going where. You may choose to map your garden in a notebook, a computer spreadsheet, or by using old-fashioned labels stuck in the ground. Whatever you do, do not rely on memory. Otherwise, in spring someone may accidentally remove the very plants you so carefully seeded in autumn, thinking they are weeds because you don’t remember. This is especially true if you’ve planted a wildflower mix because the seedlings won’t all look the same.
Sleep, Creep, Leap
Planting perennials often takes a bit more patience than growing annuals. There’s a saying that can help you remember to be patient: “The first year they sleep, the second year they creep, and the third year they leap.” (For annuals, you can remember, “Live fast; die young.”)
Perennials need time to establish root systems so that they survive through the lean times of winter, and the first year the seedlings may appear very unimpressive, sending out small leaves but not much more. Underneath the soil, growth is happening! In year two, the plants start to put more energy into leaf and flower production. In the third year, healthy plants will be well established and take off. This is another reason why some gardeners prefer to start seeds in the fall – it can give seeds a tiny bit of a head start to establish roots and become hardy that will pay off later.
Filling in the Gaps with Annuals
Some of our wildflower mixes have both annual and perennial varieties – and even a few biennials. This is because annuals will die after the first year, but they’ll provide color and interest while perennials are established. This prevents a lackluster wildflower garden and gives pollinators and other wildlife valuable nectar and pollen. If you’re interested in having a bit more control over what grows in your garden, it’s a great idea to use annuals to fill in the gaps of color while you wait to see what plants thrive and what plants you may need to rethink.
Growing perennial plants is richly rewarding, and a little bit of patience can pay off big dividends. A little bit of foreknowledge and understanding of the life cycle of these plants can help you to plan out your garden in advance. You can even get started on next year’s garden right now. Here are a few ideas to help you get started.