Updated: Nov 22, 2021
There are two secrets I will now share with you that many within California's horticultural and landscape industries already know. The first is all too often forgotten by everyone else; autumn is the best time for planting. Annually, our Mediterranean climate starves us for rain we had not seen or felt for months, and in our drought stricken state, nearly a year has gone by with only brief respite last winter. While we wait on pins and needles for our Santa Ana and Diablo Winds to pass without enraging wildfires, hope rests on winter rainfalls. With that hope is opportunity. If we install our plants in Autumn, they will take advantage of cool, moist soils, growing their roots downward, even if not too much is going on above ground. We can even reduce irrigation schedules because soil remains moist longer. This means that plants will establish more quickly than any other time of year, and the reward in spring is a punch of new growth that is challenging to achieve when planting in later, dryer seasons.
I once knew a landscape architect that embraced this seasonal rhythm. Yep, only one. Her schedule was established, and clients must be willing to work within its constraints. In short, her design work occurred in spring and summer, the dry seasons, and project installations happened in autumn and winter, to give plants their best chances of success. Unfortunately, most clients and the nursery industry are not in sync with this schedule, where nurseries in particular are winding down their availability of plants making installation late autumn/winter schedules difficult. For retail nurseries, autumn is a time to clean out old inventory in preparation for winter holidays, bulb sales, and if space allows, a focus on indoor plants.
This means that autumn in retail nurseries is full of what we call seasonal color to fill vacant tables: Cyclamen, Viola, and our subject species, Chrysanthemum, provide splashes of color, hoping for impulse buys to follow the pumpkin spice craze. These plants make up what we call bedding plants, providing pops of color in what would otherwise be a dreary landscape. The public uses these as annuals; once their color is finished, the plants are tossed in the compost bin and replaced with the next seasonal display. Which leads me to secret number two: many "annuals" are actually perennials that can return year after year if we are patient. Chrysanthemums are a great example.
Last year I succumbed to the impulse buy, feeling the need for some seasonal color. I never bought mums for myself, feeling they were an unnecessary indulgence. They were small, bloomed prettily, but instead of tossing them, I removed the flowers and planted what remained. As winter approached, they did what most herbaceous perennials will do and died back to the ground, leaving me with bare soil in my containers. I was okay with that, because I do the least of my gardening and outdoor entertaining in the winter, so there the pots sat.
When spring arrived, so did the mums. Starting with miniscule green starts, it would not take long before I could confirm their return for another year. As summer warmed them, their growth became dense. Now and then I would pinch the growth to help branching, knowing this simple effort would encourage more blooms. Autumn is here, the nurseries filled with little 4" mums; mine are the size of small shrubs, at least four times larger than when I purchased them.
Designers and clients do not have the patients for this life cycle, unless a horticulturalist is on board for ongoing maintenance and garden programming. These perennials can be interplanted with showy species while the others are resting, such as including early spring bulbs or herbaceous ground covers. There is a method to the process, providing everyone is agrees, and mums for one can be reused each year. This would be an easier discussion if a layer of snow covered the plants in winter, as what happens in other regions. People expect winter dormancy. But in the land of endless sun, the expectation is quite different.
There are numerous chrysanthemums on the market today; most can be treated similarly to how I described above, but their return in the spring, like many herbaceous perennials, is a hit or miss depending on numerous factors. For designers who are designing color beds, you have many choices based on current availabilities, flower colors, shapes, and sizes should all be taken into consideration. Know, however, that mums are grown for two primary purposes, indoor floriculture and outdoor landscapes. Indoor plants are tender; avoid them unless the landscaper or client is willing to "harden off" the plants for next year. Outdoor collections are already prepared for outdoor use, so choose wisely.
This is a quick overview by the Louisiana State University Agricultural Center, but I would modify one point. While the presenter distinguishes the difference between florist mums and landscape mums, where florist mums are composted each year, gardeners can still plant florist mums in gardens. They will need additional care to achieve their showy flowers, but for professionals and hobbyists, the reward might be worth taking a chance and seeing how they perform the following year. If as a specifying landscape designer finds their future care is uncertain, then choosing the landscape mums may be the best direction.
Botanical Name: Chrysanthemum x morifolium
Other names that might be encountered: C. x morifolium; C. x grandiflorum; Dendranthema x grandiflorum
Chrysanthemum: Greek, khrysos for gold, and anthos for flower
Moriflolium: With leaves like a mulberry, from the genus Morus
Common Name: Chrysanthemum; mum
Family Name: Asteraceae
Positioning: Foreground, potted
Garden Themes: Autumn seasonal, butterfly, cottage, courtyard/patio, cutting, culinary
Uses: Accent, border, mass, specimen, container, edible (flowers), floriculture
Type: Herbaceous perennial
Form: Round, upright
Size: Highly variable by cultivar; up to 6' tall
Outstanding Feature(s): Flower
Shape: Lanceolate, ovate
Margin: Serrate, lobed, entire
Color: Dark green above, lighter to gray-green below
Surface: Slightly pubescent
Flower: Autumn. Daisy-like but widely variable by cultivar, including color. Edible, may be fragrant, showy. Colors range from white to shades of yellow, red, orange, purple, pink, and green. Available cultivars may also be bicolor.
Fruit: Not observed at time of posting.
cultural requirements, tolerances & problems
Sunset Zones: 2-25; H1
USDA Zones: 5-9
WUCOLS SF Bay Area Hydro Zone: Moderate
Texture: Sand, loam
Moisture Retention: Well-drained with consistent light moisture
pH: Slightly acidic
Tolerances: Deer, rabbit
Branch Strength: Brittle
Insects: Aphids, spider mites, leaf miners, thrips
Disease: Leaf spot, rust, wilt, powdery mildew
citations & attributions
Bayton, R. (2019). The Royal Horticultural Society's the Gardener's Botanical: An Encyclopedia of Latin Plant Names. London: Mitchell Beazley.
Extension Gardener. "Chrysanthemum x morifolium." North Carolina State University, Raleigh. Accessed on October 9, 2021, from https://plants.ces.ncsu.edu/plants/chrysanthemum-x-morifolium/.
Home and Garden Information Center. "Chrysanthemum Diseases and Insect Pests." Clemson Cooperative Extension, Clemson. Accessed on October 9, 2021, from https://hgic.clemson.edu/factsheet/chrysanthemum-diseases-insect-pests/.
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on June 28, 2021.
All photos by TELCS.