Intro to Hardy Annuals, aka "Cool Flowers"
Did you know there’s an entire subset of flowers that can be planted in the fall to bloom beautifully in late spring or early summer? That’s right! These resilient flowers thrive when planted before winter, enduring the colder months as tiny seedlings, then emerge strong and victorious the following season.
These plants, known as Hardy Annuals or “Cool Flowers” in the cut flower industry, often need a lengthy, cool period to reach their full potential. During this time, they develop deep, healthy root systems that prepare them for a spectacular bloom as soon as temperatures rise.
Favorite Tried and True Hardy Annuals (Broken into Categories)
- Ammi
- Bachelor Button, aka “Cornflower”
- Bells of Ireland
- Buplerum
- Dianthus, Sweet William (actually a Tender Perennial)
- Feverfew (*Tender Perennial)
- Nigella
- Monarda Lambada
- Larkspur
- Snapdragon
- Sweet Pea
- Cress
- Honeywort
- Campanula, aka “Bellflower”
- Scabiosa, aka “Pincushion Flower”
- Iceland Poppy
- Rudbeckia, aka Black Eyed or Brown Eyed Susan (*Tender Perennial)
Can Hardy Annuals Be Planted in the Spring or Summer?
Good question! The answer is: it depends! Several factors influence the success of growing hardy annuals, with weather being a big one. If spring is cool and damp, followed by a mild early summer, these plants will likely thrive. Hardy annuals flourish in cooler temperatures—hence the name “cool flowers.” But as soon as the heat and humidity rise, they’ll start to struggle.
Another crucial factor is timing. If you can get these flowers in the ground early—by MARCH, when most people (at least in Maryland) aren’t even thinking about gardening yet—they might still do well. This early start gives them time to grow and bloom before any heat waves hit. However, many gardeners, myself included, don’t have beds ready that early in the year. Here in central MD, we sometimes still have snow on the ground! This also means starting seeds 1–2 months in advance, around January or February. So, while spring planting is possible, it does require considerable planning, preparation, and foresight.
That said, if you live in a growing zone or climate especially suited to Hardy Annuals—one with low humidity and summers that rarely climb above the 80s—then you won’t need to worry about any of these challenges. Go ahead and enjoy growing these beauties all summer long!
Benefits to Fall Planting (as opposed to) Spring or Early Summer Planting
This section is relevant for zones/climates where summers are long and hot like here in Central Maryland, but may not apply to you so feel free to skip!
- Earlier blooms Fall-sown hardy annuals flower earlier than spring-sown plants.
- Stronger plants The roots of fall-sown plants expand in the warm soil over winter, resulting in stronger plants in the spring.
- Less work in the spring Fall-sown plants can reduce the amount of work you need to do in the spring.
- Follows nature Many wild plants shed their seeds at the end of the growing season, similar to fall sowing.
So why is this group of flowers relatively unknown? The truth is that, despite the name, Cool Flowers are not very marketable. By the time fall arrives, most gardeners are worn out from a busy summer and ready for a break. The idea of planting seedlings just as temperatures are about to drop feels unappealing—or even confusing—to many gardeners, especially those less experienced. Additionally, stores often clear nursery space to make room for holiday merchandise. As a result, hardy annuals have largely fallen off the radar for the average consumer.
What's Next for Branches & Batches?
This week, I’m starting to transplant hundreds of hardy annual seedlings into my prepared beds. Many of these can also be direct-seeded (see the chart linked below for those that prefer this method). However, I fell behind and didn’t get my beds ready for direct seeding in the minimum required 4–6 weeks ahead of our first expected frost, so transplants for me! In my part of Maryland, the first frost is predicted to be around November 3rd, but it may vary depending on your location. Here is a good reference for Maryland gardeners.
Most likely, it’s too late to start most of these from seed for fall planting, but if you’d like to try growing hardy annuals, there are still options: consider buying plugs, winter sowing, or planting in “very early spring” (March).
For more information on how to grow these hardy annuals yourself, you can download my handy chart with all the essential growing details here.
Conclusion
Is this your first time hearing about this category of flowers? You’re not alone! I only learned about them in the past couple of years, even though I’ve been gardening much longer. For example, I knew what Larkspur was, but I didn’t know the right way to grow it. I spent years trying to grow cool annuals incorrectly, resulting in weak, struggling plants.
Hopefully, this post gives you the information you need to grow them successfully—no trial and error required!
FREE Fall Seed Sowing Chart
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