Annuals for Cutting

by Kirk Jones
Community Gardener, Winter 1999

When I first started gardening with Project Grow, I grew mostly vegetables. Then after a couple of years I started to throw in a few flowers. Some, like sunflowers, I grew for fun, and others, like cosmos, I grew for cutting. As years went by, I became more and more interested in flowers, and I gradually ended up devoting most of the garden to flowers, with only a little room left over for a few tomato plants, herbs, and snow peas.

It is a lot easier to grow flowers for cutting than it is to grow them in a border by the house. When growing flowers in a border, you need to plan which flowers look good together, relative heights, and consider how the plant looks when it is not in flower.

I can endlessly fuss about these problems in my borders at home and so it is a relief to be able to forget about all this stuff when choosing and planting flowers for cutting at Country Farm. After all, with cut flowers the only thing that matters is how it looks when arranged in a vase. Within reason, I can adjust height with shears. If the colors clash, I can just pull out the offender and put it in a different vase with better companions.

There are plenty of great perennials for cutting, but since many Project Grow gardens are tilled each season, I’m going to focus on annual flowers. A true annual plant grows, flowers, sets seed and dies all in one year. Some plants that are sold as annuals are actually perennials, but for the purposes of this article, an annual is anything you can bring into bloom the same year you start it.

Annuals can be classified by their cold hardiness. The very first frost tolerant ones are called hardy annuals. Many of these will actually sprout in late fall, live through the winter as tiny plants an inch or two high, and then grow into robust plants with the first warm weather. Half-hardy annuals can tolerate light frosts. Tender annuals cannot tolerate cold at all, and the slightest frost will kill them.

How and When to Start
Most annuals can be seeded directly into the ground, but I almost never do that for several reasons. First, the weeds always come up first, and by the time I distinguish my seedlings from the weeds, they are growing in a turf-like mesh of weedlings. Second, if the seeds don’t go in until May or June, I may not have anything in bloom until August or later, whereas if I start things inside I start getting flowers as early as mid-June. Lastly, it allows me to start “gardening” under lights while it is still winter outside. Except where noted below, I usually start the hardy and half-hardy annuals 6 to 8 weeks before the last frost. In southeast Michigan, that is March 25th to April 8th.

Once an annual sets seed, its will is finished, so it is very important to either cut the flowers for the house, or remove the spent flowers before they go to seed. Treated this way, many annuals will keep producing flowers until killed by frost.

Over the last six years, I have tried quite a few different annuals for cutting, with results ranging from complete disaster to smashing success. The following are some of the plants I’ve like the best.

Bachelor Button (Centaurea cyanus)
Hardy
I dote on blue flowers, so I always grow the blue ones, but Centaurea also come in garnet, pink, and white blends. I’ve read that if you remove the side buds you can get huge, long-stemmed flowers, but I never remember to do that. Centaurea frequently self-seeds.

Fragrant Pinks (Dianthus suerbus)
Hardy
Most dianthus make great cut flowers because they last a long time in a vase and are fragrant. There are lots of pinks to choose from, but my favorite is a strain called “Rainbow Loveliness.” The petals are deeply fringed and look almost like clusters of feathers. They are extremely fragrant. The books say they smell of jasmine, but I always say they smell clean and fresh, like fabric softener. These plants are actually perennial and can be started as much as 10 weeks before last frost.

Cosmos (Cosmos)
Tender
I’ve tried tow kinds of cosmos. The first, C. bipinnatus, is the cosmos most commonly grown. It comes in shades of red, pink, and white. I have had the best luck direct seeding these plants. The second variety I like is Klondike Cosmos, C. sulphureus. I grow the Sunset strain, which is about 3 feet tall and bright yellow orange. I love these in combination with blue and purple flowers.

Panicle larkspur (Consolidia regalis)
Hardy
Panicle larkspur has thing, almost invisible, leaves and loose, open sprays of flowers. The effect is like a blue baby’s breath. These do not transplant well, so direct seed or start early and expect losses. Once you get them, however, you have them forever because this plant reliably self seeds.

Calendula (Calendula officinalis)
Hardy
Calendula are double or single daisies that come in shades ranging from cream, yellow, and orange. Calendula prefer cool weather, and if you keep them picked, they will often produce flowers until late in the fall.

Candytuft (Iberis amara)
Hardy
This is another plant that has reliably self-seeded in my Project Grow plot ever since I first planted it. It produces white hyacinth-like umbrellas of flowers. The stems are short, but it blooms early and lasts a long time after cutting.

Phlox (Phlox drummondi)
Half Hardy
I never had heard of annual phlox until one fall when I picked up a sale packet of seed for a nickel. This has turned out to be one of my favorite cut flowers. The flowers are a smaller version of perennial phlox and come in shades of red, pink, salmon, white, and some bicolors. They will need support if you want long stems.

Scabiosa (Scabiosa atropurpurea)
Tender
The common name for scabiosa is pincushion flower. Each flower is a two-inch wide mound of tiny florets. While still in bud the blooms look like a tiny beaded button. These plants usually need to be staked. They don’t spread much, and the stems are very long and thin so the plants can be spaced closely.

Sunflowers (Helianthus annus)
Hardy
While the big sunflowers grown for seeds don’t look too great in a vase, there are several good strains bred especially for cutting. I really like a smaller pale cream one with a black center called an Italian White.

Sweet Pea (Lathryus odoratus)
Hardy
Sweet peas are supposed to be easy, but I have had mixed success with them. Nevertheless, they smell so wonderful I will always keep growing them. They don’t like hot weather, and in hot summers they can burn out quickly and stop blooming. In cool summers, they will bloom all summer if you keep them picked. Sweet peas must be picked or deadhead to prolong bloom.

Sweet peas are very cold tolerant, and you can plant them out as early as you would garden peas. The year I did this, they took a long time to germinate and had not put on much growth before hot weather hit. I have had better luck starting them in peat pots early inside. No matter how you plant them, sweet peas will germinate much faster if you score the seeds with a file and soak them overnight. They should swell up after this treatment. I’ve read that the ones that don’t swell won’t germinate but I can’t validate that from experience.

I have had the best luck growing an old strain called Cupani, a blue-violet bicolor with very strong scent.

If you don’t usually grow flowers, I hope you try a few of these this year, plus any others that sound interesting. Half the fun of catalog browsing in the winter is considering new plants. Every year I try one or two new things. This year I will be growing Clarkia and Venidium for the first time.