Kick up the color in your garden with these fiery autumn plants.
By Panayoti Kelaidis
Colorado autumn is rightfully celebrated in our mountains—crisp air, golden aspens, azure skies and puffy cumulus clouds. It’s the stuff dreams are made of!
Our autumn gardens, however, usually need some help. Spring brings tons of bulbs, and most perennials flourish in early summer, but fall becomes the time of yellow composites, golden daisies and purple asters. And did I mention yellow daisies?
Nevertheless, a bevy of sexy plants can do wonders to liven up the fall garden. Here are my favorite dozen.
Autumn Crocus (Colchicum autumnale ‘Water Lily’) Dimensions: 7-inches tall, 4-inches wide
First, this is not a crocus, which is in the iris family and has only three anthers. But it is a sad Colorado garden that doesn’t sport its share of autumn crocus (which is a lily cousin with six anthers inside its ruddy goblets). The dirty little secret no one tells you is that these plants have huge sheaves of bright-green springtime foliage that can overwhelm small plants. So plant them in the back of your shady border. I love all Colchicums—some of which bloom in spring instead—but this commonly sold, double-flowered form is a keeper. It clumps up quickly and can be divided in midsummer. All it needs is shade and not too dry a spot; then stand back and prepare to be dazzled.
Cushion Spurge (Euphorbia epithymoides, also Euphorbia polychroma) Dimensions: 15-inches tall, 20-inches wide
I know, this plant blooms at the height of spring. But this deciduous spurge is a garden mainstay, with its brash chartreuse bracts and trim habit throughout the season. Fall brings a second season of drama—the leaves turn pink and orange in late September, and the show goes on well into early winter. It’s worth growing this plant for the foliage alone.
Spurge is also enormously accommodating in the garden, doing particularly well in rich soils with some water, but it can adapt to part shade and even rather stiff mineral soils. So there’s no excuse for not growing some in your garden.
Hardy Fuchsia (Fuchsia magellanica) Dimensions: 40-inches tall, 40-inches wide
Several fuchsias are apt to prove hardy here, but this is the commonest one by far. This particular plant originated in the southern Andes, where I saw it growing almost to tree line in the Argentinian lake district and also in Chile. The flowers may not be as fat and flashy as the tender sorts you see in humid maritime climates, but the scarlet and purple earrings that adorn this fuchsia from midsummer to winter are svelte and showy in their own way. At least, hummingbirds think so.
My brother-in-law has grown this plant in Boulder for decades, and we have some lusty specimens at Denver Botanic Gardens. This fuchsia is likely to prove hardiest in the Front Range urban corridor, but it needs rich soil, lots of water and careful placement in a protected microclimate. It’s worth every effort, though, if only to impress your gardening friends.
Dalmatian Cranesbill (Geranium dalmaticum) Dimensions: 5-inches tall, 20-inches wide Geraniums are perhaps the most gorgeous foliage plants in the hardy garden. Their lush, plush leaves are usually a vivid green or blue-green, and are always attractive in the growing season. This particular geranium is the champion of the smaller cranesbills. I have some mats that are more than 4 feet across in my rock garden. Throughout most of midsummer their cool pink flowers spangle these trim mats of deeply cut, bright-green leaves.
If this were all the plant did, it would still be near the top of my list. But in late October, the real show begins. The compact foliage mat begins turning a deep red over here, a bright pink over there. Within a few weeks—usually right after the first hard frosts—the mat positively blazes with hot colors. This show goes on through late fall well into winter. This plant is a champion among smaller ground covers, so you must find a spot for it in your garden. There is also an apple-blossom-pink form (nearly white) that’s just as vigorous.
Cape Figwort (Phygelius capensis) Dimensions: 36-inches tall, 24-inches wide
Most Coloradans who first see this plant think it’s a very shy penstemon, as the flowers are quite similar to some of our red-flowered summer penstemons. However, the texture is much waxier and the bearing demure—the blossoms are tucked head down and curved backward in a peculiar fashion, almost as though they are ashamed. Some people fear that any plant from Africa is tender, but I’ve seen figwort growing above 9,000 feet in Lesotho, where it experiences extreme subzero cold for months on end. But even the lower-altitude forms are quite hardy in plain old border conditions in Colorado.
Many color forms of this plant are in cultivation. Local nurseries stock a particularly brilliant scarlet form that starts blooming in late June most years and lasts until fall. If it’s happy (and it’s not too hard to please), the plant can sucker modestly to form quite a large mass. Some years it’s almost shrubby, so I prefer to cut mine down to the ground in early spring. Like our native penstemons, this plant is a hummingbird magnet.
Redleaf Japanese Barberry (Berberis thunbergii ‘Crimson Pygmy’) Dimensions: 4-feet tall, 3-feet wide Japanese barberry is considered invasive in wetter parts of the country. But I have grown this in many gardens and have never had a self-sown seedling in Colorado, except for one specimen that a bird inadvertently planted in the Rock Alpine Garden almost 30 years ago. That specimen has grown into a dense mound near that garden’s entrance, and I doubt if any of the thousands of plants that have grown in the rock garden have had as many compliments or more questions asked about it than that barberry.
This dense shrub has spoon-shaped leaves that are bright green in the typical form and deep burgundy in ‘Crimson Pygmy’. It can be shaped and sheared, but the typical wild form is quite slow growing and compact, and ‘Crimson Pygmy’ even more so. This plant can make a formidable hedge, and deserves more use in the garden. The rounded shrub is dazzling when in yellow spring bloom, but even more so in autumn, when the purple leaves turn brilliant reds and oranges and you could almost call the fire department, it is so fiery and bright.
Threeleaf Sumac (Rhus trilobata) Dimensions: 4-feet tall, 4-feet wide
I doubt there’s a more common plant than sumac in the lower foothills, and threeleaf sumac is a nearly indestructible native that deserves a spot in local xeriscapes. (I grow several.) The chartreuse fringe of flowers in spring is OK, and the mass of green through the summer is OK. But in late September, the foliage turns tints of scarlet, orange and burgundy, and then the plant becomes a highlight of any garden.
Sumac can grow rapidly from small pots, so don’t overplant it unless you intend to cover a lot of ground. Some spectacular new selections of this species, and its closely allied eastern cousin Rhus aromatica ‘Growlow’, are available—the latter a mat-forming clone that is a superb ground cover. Best of all, any forms of this plant thrive in almost any soil, and they require little water or care, once established.
Mexican Sage (Salvia darcyi) Dimensions: 3-feet tall, 4-feet wide
There’s no end of salvias in garden centers nowadays. Not surprising, since the genus includes nearly 1,000 species found everywhere in the world—especially the New World tropics. When this particular species is grown well, I doubt a showier salvia exists anywhere that can hold a candle to it. The attractive, apple-green foliage is covered with hairs, and the flowers bloom from July to frost in columns of fiery scarlet. Hummingbirds like this salvia almost as much as I do.
When first collected a few decades ago, this salvia was not thought to be hardy. But it persists lustily in many gardens throughout the Front Range, and it’s worth every effort to establish. I can assure you that you will be the envy of your friends and neighbors if you do.
California Fuchsia (Zauschneria californica cvs.) Dimensions: 1-foot tall, 3-feet wide
The California fuchsias are not restricted to California, nor are they truly fuchsias (they are in the same family, however). I don’t think I’ve seen one of these plants that you can’t grow in most Colorado gardens.
Few flowers make a more vivid display of orange to true red. The silvery or green mats are attractive in their own right, but when the scarlet tubes of flowers appear in abundance in late summer and fall, stand back! Hummingbirds will buzz you, and your garden may have work ahead of it, as some of these fuchsias are badly affected (as are most plants in this important family) by flea beetles in a hot, dry season. But just cut these back, and the fresh growth is usually left alone. I find it best to plant this in early summer so it’ll establish well before its autumn glory.
Rabbitbrush (Chrysothamnus nauseosus, the new dwarf form in Plant Select) Dimensions: 24-inches tall, 30-inches wide
There was a time when I thought rabbitbrush was a bit too coarse and wild for our city landscapes. But several decades ago, a smaller form began to circulate among growers that made very dense domes of foliage and flowers in summer months. These dwarf forms are now in Plant Select, where they’re subject to local whims and weather gods.
This shrublet is a dense mound of silver-blue in summer, with a mass of short, yellow flowers that completely cover the plant. In autumn, the mass turns into a golden dome. Few shrubs are as drought-tolerant or easily maintained as this miniature rabbitbrush, and it’s one native that’s trim and neat enough for a formal garden.
Great Plains Blazing Star (Liatris punctata) Dimensions: 14-inches tall, 8-inches wide
Liatris is a mainstay of perennial borders around the world, and most need abundant irrigation in summer to thrive. Our Great Plains species, however, is indestructibly drought tolerant, and the plantings in the Plains Garden at Denver Botanic Gardens thrived and bloomed robustly during our last great drought cycle. The purple spires of flowers last much of August and September, making this plant a must for your xeriscape. Do not water it too much or it is sure to flop and look ungainly.
Evening Star (Mentzelia nuda) Dimensions: 4-feet tall, 3-feet wide
The Great Plains are often much showier in late summer than they are in late spring or early summer. There are no end of daisies and daisy-family plants, which transform the prairie with their bright purples, whites and pinks, not to mention ever-present yellows. But I doubt if any plant blooms more profusely in our native lands than this gorgeous ivory-white flower, which almost suggests a Cereus cactus when it blooms. The flowers can be more than 3 inches across, with many petals. They often do not open until late afternoon, but they can persist until late the next morning.
Few plants are as refulgent and exotic as a large clump of evening star in bloom. But be aware: The foliage is covered with tiny, hooked barbs that are painless, but act like Velcro and gather things to them. This gorgeous plant is readily established and lives a long time. Few native wildflowers are so easily grown, and yet still quite rare in local gardens.
Panayoti Kelaidis is director of outreach and senior curator at Denver Botanic Gardens.