5 Cool Flowers to Plant Now | Lisa Ziegler on Growing Hardy Annuals

Cool Flowers, by Lisa Mason Ziegler

“ Hardy annuals naturally grow into strong plants when they get the chance to develop in cool weather. ”

This Virginia flower farmer has grown cut flowers on a small urban farm since the late 1990s. She farms intensively and organically on a little over an acre of open field, producing thousands of stems a week from spring into fall. She sells to high-end florists nearby and directly to customers through a members-only garden share program.

Much of her time off the farm goes to teaching organic gardening and cut flower growing, and her talks have taken her far beyond what she ever expected.

She turned one of her favorite talks, on fall-planting hardy annual flowers, into a book called Cool Flowers, and has also written Vegetables Love Flowers, about pairing cut flower gardens with organic vegetable gardens.

Cool Flowers explains how and when to plant hardy annuals for success in fall or very early spring. Once their needs are met, she points out, this varied, easy group of flowers blooms weeks ahead of typical spring-planted annuals, which for flower farmers means flowers, and income, much earlier.

Any time is a good time to start planning cool flowers, she says. The Hensley's team asked this experienced SlowFlowers member to share more.

An armful of snapdragons (Antirrhinum majus) headed to the flower shed.

In her Zone 7 garden, the first snaps to bloom, in April, are the tall, sturdy 'Chantilly' Series. The hardiest, and last to bloom, she says, are the 'Rocket' snapdragons.

After many years as a flower farmer, how would you sum up your philosophy?

I love farming, being outside and driving the tractor. I've simplified my business so I can enjoy the ride. Instead of growing what I love, I grow what sells week after week with the least fuss, a few dozen varieties over the season.

So what do you grow?

The basics: sunflowers, celosia in every color and form, including our favorite, 'Sylphid'. I grow bells of Ireland and bupleurum, and lots of snaps, sweet William, sweet peas, and zinnias. I don't need to grow fussy ranunculus because I'm not after wedding florists. Weddings are seasonal, and I don't want to work weekends, which is also why I quit farmers' markets. My florist business has always come first.

How many florists do you sell to, and how?

As I head toward semi-retirement, I've cut back from many commercial accounts to just a handful of florists, my original customers, who buy everything. Selling the harvest takes minutes because I just send a list. They know my flowers and they know me, so they order what they want and I don't have to explain or persuade. I'm selling to people who use flowers every day in their work.

Over the years, how have you worked out the best use of your land?

I grow almost all annuals and do a lot of succession planting, because annuals give the most flowers for the money and space. Spring is full of cool flowers, poppies and bells of Ireland and so many others. Through summer we grow lisianthus, and we try to have zinnias as early and as late as we can. In fall, of course, we want dahlias . I've learned to grow more of the flowers we always run out of.

How did you learn your cool flower methods?

I read in Lynn Byczynski's book The Flower Farmer that you can plant snapdragons in fall. I looked for more hardy annuals and went from there, since I'm in the city and can't have hoophouses, so I pushed field-grown hardy annuals as far as they'd go. This method is the best-kept secret in flower farming, and it brings in a big share of my income in April, May and June, all from the field.

An armful of bells of Ireland (Moluccella laevis)

When do you plant cool flowers, and which ones?

As a general rule, hardy annuals that survive in your hardiness zone can go in 6–8 weeks before your first fall frost. They start from seed, overwinter as young plants and get well established, so when spring comes they grow quickly into strong plants.

I've overwintered every hardy annual in Cool Flowers that's hardy to USDA Zone 7 and warmer.

Since you're in Zone 7, growers in colder zones might think this won't work for them.

What I'm seeing, especially with some Canadian growers I advise, is that fall planting usually isn't an option in Zones 3 or 4. But cool flowers can go in weeks before you'd plant tender annuals in spring. I suggest planting 6–8 weeks before your last spring frost.

Say your last frost is June 1, when you'd plant zinnias and sunflowers. You can plant cool flowers 6–8 weeks earlier, roughly early to mid-April, and you'll get flowers much sooner.

An armful of sweet William and snapdragons

How do you plant?

Early spring planting depends on preparing beds in fall. I call it "very early spring," not "late winter." When we plant then, around mid-February for us, we sweep snow off the prepared beds. I use biodegradable film and wait for a sunny afternoon when the snow is melting, then sweep the beds and plant stock, sweet William, snapdragons and more.

How do you prep the beds?

We always spread a couple of inches of compost, such as composted manure or leaf mold, then work a dry organic fertilizer into the top 4–5 inches at the label rate before planting. We cover the beds with biodegradable black film, even ones that won't be planted until spring, and the soil warms under it through winter.

So you plant in fall and in very early spring?

Yes, because that stretches out the harvest of those flowers.

How many hardy annuals do you grow?

Peeking out from behind a mass of tall bupleurum

I've grown every cultivar in Cool Flowers. The book has a quick-reference list of all the cool flowers and the zones they're known to be hardy in.

For many of these flowers there's no published hardiness data, so I list Zone 7, my own zone, because I know they not only survive but thrive outdoors on my farm.

Since the book came out, I've heard from growers in Zones 5 and 6 who fall-planted in the field and used low tunnels with great results on some flowers I listed as hardy only to Zone 7.

For someone trying hardy annuals for the first time, what are your can't-miss picks?

I'd suggest 4 from Cool Flowers, plus a new fifth.

Snapdragons (Antirrhinum majus) should be started indoors and transplanted. They're very cold-hardy, reported hardy to about Zone 4, which covers most of the country. I grow several kinds, with the 'Chantilly' and 'Madame Butterfly' series at the top of my list.

Rudbeckia 'Indian Summer' (Rudbeckia hirta) also go in as transplants started indoors. They don't mind cold, wet or ice. Planted in fall, 'Indian Summer' sometimes blooms by Mother's Day.

For direct sowing, I suggest bupleurum (Bupleurum griffithii) and larkspur (Delphinium consolida). And by the way, I could grow two acres of bupleurum and my florists would still want more.

What's your newest pick?

Stock (Matthiola incana), started indoors and then transplanted. I wasn't sure about stock when Cool Flowers came out, but I've since learned it survives fall planting in my Zone 7 garden. It actually tried too hard to bloom at Christmas, so now we plant it only in very early spring, about 8 weeks before our last frost. Nights are well below freezing and days are cold, and stock does beautifully.

It's also the most reliable germinator I've ever grown, very easy from seed. I love the 'Quartet' Series , and with this method we can harvest by Mother's Day.

Thanks! That's given us confidence to try fall-planting cool flowers.

More people should try it. Our grandmothers did; they may not have kept detailed records, so we don't have exact zone data for every variety, and zones and microclimates change over time. But it's nothing new. While researching Cool Flowers I found a 1951 book that covered planting hardy annuals, the Better Homes & Gardens garden book!

When I teach growers this method, I tell them: these plants aren't afraid of the cold, so you don't need to be either!

Cool Flower Growing Info

Field-grown 'Quartet Yellow' stock doing well in early spring (Zone 7)

1. Snapdragons

• Growing information
• Production guide PDF

2. Rudbeckia

• Growing information

3. Bupleurum

• Growing information

4. Larkspur

• Growing information
• Production guide PDF

5. Stock

• Growing information
• Production guide PDF

Row covers coming off in late March in her Zone 7 fields.

Methodology

• Row cover comparison chart PDF
• Managing Low Tunnels Illustrated guide based on Eliot Coleman's methods
• Mulch and landscape fabric comparison chart PDF
• Hardiness zone map

Additional Resources for Cool Flower People

• The grower's speaking schedule
• The grower's farm website
• Hear the grower on the Slow Flowers Podcast
• The Flower Farmer, by Lynn Byczynski
• The grower's books and media