Cool-season annuals, otherwise called “cool flowers,” are perhaps the most overlooked and underrated plants in the home gardening world. It’s likely they’re often left out of gardens simply because of when they need to be sewn in the ground. Depending on the type, cool-season annuals usually need to be planted about six or so weeks either before the first fall frost, or six or so weeks before the last spring frost. And casual gardeners (like me) often don’t think of these times of year as optimal for growing. But the truth is, with a bit of extra prep and planning, cool-season annuals have the ability to transform the appearance of your garden from “meh” to “wow.”
First, let’s take a quick look at cool-season annuals from a bird’s eye view:
- Cool-season annuals prefer chillier temperatures. I know. Who would have guessed? But hey, sometimes the universe just makes sense, right?
- As noted, they’re planted six or so weeks before the first fall frost, or six or so weeks before the last spring frost.
- As such, you’ll get blooms in late spring or early summer, which is a most welcome sight, particularly if you live in an area that has a seemingly endless winter.
- Determining what and when to plant will ultimately depend on where you live and when your first and last frost dates are. Use this handy map from the USDA to determine your hardiness zone, and this Farmer’s Almanac site to determine your frost dates. As you might have guessed, these two pieces of information will inform you of both what and when to plant.
- What to plant. Before purchasing cool flower seeds, look up what USDA zone they’re in in order to see if they’ll survive in your location. This information can usually be found on the back of seed packets.
- When to plant. Similarly, the back of your seed packet will also tell you when the best time to plant will be—but as a general rule of thumb, for cold flowers, you can either plant before the first frost (for a spring bloom) or when the soil begins to soften up in the spring (for a summer bloom).
- Another common method to ensure success is to germinate and begin growing your seeds indoors. This will allow your plant to grow a hardy root system before braving outdoor conditions.
Most Versatile Cool Flowers to Plant
Calendula Hardiness zones 2-10. Also known as marigold, calendula has been a cool season favorite dating back to the Romans. It’s a versatile, stunning, and edible plant. Can be direct-sewn or planted as a transplant.
Cornflowers Hardiness zones 2-11. Cornflowers grow great when direct sewn. When mature, they produce gorgeous deep blackish-purple blossoms.
California Poppies Hardiness zones 3-10. These poppies can be directly sewn and thrive in cooler climates.
Sweet Peas: Hardiness zones 3-8. Sweet peas prefer to start indoors and be transplanted to the ground. They can grow upwards of seven feet, so be sure to provide proper support, like a trellis.
