Did you know there is a whole world of beautiful flowers that thrive on cooler temps. It's no secret, but it seems so.
Not many people talk about this now, but I have planting records from my great, great uncle Al that showed the vegetables and flowers he sowed in fall and very early spring. Our ancestors were so much more in touch with the seasons because their lives depended on it! These cool season plants have always been there, we just need to relearn how to grow them correctly so they can thrive and delight!
So what are they?
Cool flowers, also called cool-season hardy annuals (as opposed to tender annuals) are a set of flowers that prefer growing in colder temps. Because they like cooler temps they bloom in early spring – extending the flower lover’s season – think of blooms in late May and early June (for those of you in Wisconsin). Dreamy!
What’s the difference between hardy and tender annuals?
Cool flowers (hardy annuals) live for one year and can be planted in the fall BEFORE our first frost or early spring before the last spring frost when the temperatures are cool. Tender annuals live for one year, need to be planted AFTER last frost in spring, and prefer growing in the heat of summer.
To dive deeper, if a plant is hardy in your zone (zone 4 for me) that means it is hardy to plant in the ground in fall and will survive the winter cold and come up in spring with a strong root system, more disease resistant and stronger stems. If a plant is not hardy in your zone (for me that would be any zone 5-9), it will not survive if planted outdoors before winter. However, some plants still like the cold and will thrive being planted in early spring - which for me in my zone, means as soon as I can work the soil in March or April.
So how do you know what to look for? Let’s break down a seed packet and take a look.
To understand which flowers can be planted as cool flowers, first you need to find your hardiness zone for your growing area and the first and last spring frost date. Look here for hardiness zones. Look here for frost dates.
Here in New Richmond, WI, I am in zone 4b and my first fall frost is September 28, and the last spring frost date is May 11.
- This shows a map of when that sunflower can be sowed outdoors. In Wisconsin it shows June. This is a basic way of saying it is a warm season flower because June is warm here.
- Details explain that these sunflower seeds can be directly planted in the ground AFTER the danger of frost.
- Bloom dates or maturity are helpful because once you know when your last spring frost is, you can count backwards 6-8 weeks and start your seeds indoors. By the time the danger of frost has passed, your seedlings can go in the ground with almost a month head start and bloom earlier. In this example, the sunflower blooms in almost 80 days. If we planted the seeds outdoors after the frost (May 11), 80 days later I would see those bright sunnies. That would be July 30th! If we started those seeds indoors 30 days earlier, we would see sunflowers bloom June 30th!
- Snapdragons are a cool flower. But this cool flower packet doesn’t give zone information, however, it does tell us some other clues.
- This seed likes to be sown in the ground 8-10 weeks BEFORE the last frost in spring. That means it can tolerate the cold. For my zone I would have to seed it in the ground at the latest March 12 – if I can get at the soil. Some seed packs will say if the seed prefers direct sowing or if it can be transplanted. This one says it can be started indoors and after 3-4 weeks be planted outdoors. So simply add those 3-4 weeks on to the 8-10 weeks before last frost and you will be able to have month old seedlings to plant. It’s a lot to digest, I know!
- Another clue. This information tells me that it likes cooler temps.
I will be planting cool flower seeds indoors starting in March for planting in the garden in April.
A few that I will be planting are shown below: Snapdragons, Bachelors Buttons, Yarrow and Feverfew. For a list of my favorite cool and warm season annuals, check out my Extending the Season Blog.