(Chrysanthemum x grandiflora, aka C. morifolium)
No flower speaks fall like chrysanthemum. Go into a nursery in October and you’ll see them in a huge variety of colors, often in large pots with rounded domes of blooms, but also in small pots to add to a fall container planting. Look carefully and you’ll likely find colors and forms of flowers that you like. Snatch up your favorites to bring home and plant in your garden for fall blooming perennial cutting flowers next year.
Chrysanthemum flowers come in a huge array of styles and colors. You will probably find some interesting ones in your local nursery but you can find many more styles and colors in specialty nurseries or in nurseries that sell online.
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They may be in the form of cushion flowers, daisy and semi-double daisy, button, spoons, quills, pompom-like football types, fuller cushion-types called large-flowered garden style flowers, and the beautiful, harder to get spiders.
Most forms produce sprays of flowers that are pretty in bouquets. While the bigger forms form smaller sprays with larger flowers. The size and number of those flowers can be controlled by pinching as described below.
Mums bloom in fall, September to frost. The shorter daylength trigger blooming. You may find a plant blooming off season. That’s because some growers control flowering in greenhouses with lights and dark cloths so they’ll bloom at any time of the year. When you plant these they will revert to their normal late summer bloom time the very next year.
Plants can range in height from 8 inches or so to 36 inches or more, usually in the 24-36 inch range. When you find them in the nursery, they’re either in a small pot or they’re in a larger pot all trimmed into a dome shape with flowers covering the surface. This doesn’t tell you how tall they’ll get when their grown in the garden. But any size is nice.
I keep a range of vase sizes to accommodate all stem lengths. Flowers of all stem lengths are pretty anywhere you can put them.
The plants are herbaceous and go fully dormant in the winter.
Growing the Plants
Chrysanthemums grow in USDA Zones 6 – 9. They’re hardy down to 10 – 20 ͦ F, and endure occasional killing frosts to -20 to -30 ͦ F.
They have shallow roots, so mulch them. Add a bit more in winter in Zone 6.
They like good garden soil and adequate water. And full sun. In a hot summer climate, a bit of afternoon shade is appreciated.
Midsummer is a good time to side-dress with compost or aged/composted chicken manure, for extra nutrients.
Pinching chrysanthemums: why, when, how, and do you need to?
You’ll find lots of advice on pinching mums…but you may not need to do much of that, or any of it. The only thing I do is cut back the stems just before the 4th of July to about half. Cut right above a node. This allows each stem to form two new stems, giving you more flowers.
You can pinch by snapping the stem or by using your thumbnail to cut into the stem with your forefinger behind it. Since I never walk into my garden without my clippers in my pocket I simply use them to “pinch”. It makes a cleaner and safer cut.
Many people pinch their mums several times—before the 4th of July— for several reasons. One is to keep the plants more compact. This makes them showier with a full display of flowers, like the domed plants. But we don’t want compact for cutting flowers, we want tall and lanky for good long flower stems.
Pinching also delays flowering, making sure they bloom in fall, not in summer. When the growing stems are pinched back, the plants take longer to grow more stems and to make the flowers. This assures they bloom later.
For cutting flowers, one pinch, or cutting back, as mentioned above, should be all you need to do. This will grow two new stems and grow two good-sized flowers or flower sprays, without sacrificing much stem length.
BUT, if you have a fine spider mum, or a football mum, and you want to get the biggest flowers, remove all the buds but one on each bigger stem to allow that one to grow larger. Pinch early for more stems, but once the buds are visible, remove those smaller stems with buds, save one, on each.
Whether you want a compact showy display of flowers on the plant or longer stems for cutting, do the last pinching—or cutting back—before the 4th of July. Why? Because once chrysanthemums set their buds, which are difficult to see when young, they produce no more, unlike most other plants. This happens after early July, so the 4th is an easy way to remember. Put it on your calendar.
If you pinch too late you risk the flowers not blooming before the first killing frost, or when the days are just too short.
You’ll probably have a few thick stems with a spray of flowers on them. The whole spray can be used very nicely in a bouquet. If the spray’s individual stems are long enough you can use flowers individually or use them in small vases.
Just use the normal harvesting treatment…or, since it’s cooler in fall, skip conditioning and put them right into the vase!
I love the daisy types with deep rich colors and white, and the quill and spoon types, in warm fall colors. I love the spiders, too, but don’t have any yet. I just get my plants from my local nursery. I buy 4 inch pots or 1 gallon sizes. They’re a nice inexpensive way to go.
How Many Plants
Having several plants is nice to mix and match for bouquets.
Fall is also time for the asters to bloom. Put them in with the mums for a shot of cooling color. And alstroemerias keep blooming when the mums are blooming, so do celosias, amaranth, and African marigolds. These can all come together for some gorgeous fall colored bouquets!