Bloomin’ Perfect: 11 Must-Have Annuals

The senior curator at Denver Botanic Gardens shares his list of must-haves annuals.

By Panayoti Kelaidis When I began my career at Denver Botanic Gardens in 1980, most of the grounds consisted of annual planting beds, often planted as late as early June. Since May was the Gardens’ Plant Sale month, staffers were too busy to plant, and planting earlier was risky due to potential frost. So it was usually late June by the time the annuals settled in and began to bloom well. One day in early September I strolled the beds and frost had nipped everything. The annuals were mostly shades of gray and black, which basically meant they had bloomed for just two months—not enough to pay rent in MY garden book!

Author Panayoti Kelaidis is senior curator and director of outreach at Denver Botanic Gardens.

So I was less than enamored of annuals when I started at the Gardens. “Weeklies,” I called them, cynically, since they only bloomed for weeks. (I never did buy Plant Delights Nursery’s famous T-shirt with a ‘Purple Wave’ petunia inside a “no” symbol inscribed with “Friends Don’t Let Friends Buy Annuals,” but I thought it was hilarious!) I was apparently so successful in my anti-annuals campaign that in a few decades, annuals had all but disappeared from Denver Botanic Gardens—excepting, of course, in pots where they still spill their flashy colors. During those decades, however, a number of annuals elbowed their way into my personal garden and settled in, rather like welcome squatters. Then several more snuck in, and I began to seek out annuals for my garden that were altogether distinct. By that, I mean the vast throng of winter-blooming annuals in the world’s Mediterranean-like climates that have been increasingly bred by horticulturists to produce reliable, longer-blooming strains that often last through our whole summer instead of burning up in the first hot spell. These new selections (many marketed by Proven Winners) are truly winners in the summer garden that provide incredible masses of color for months on end. Now I’m an annuals aficionado, and some of my favorite ones are starting to appear at local nurseries. Try a few from my list here, and you too might hop off the perennial bandwagon for a stroll amongst the annuals. And, as the culprit who helped banish annuals from Denver Botanic Gardens, I offer my sincere apologies. I’m earnestly trying to usher more annuals through the Gardens’ gates, and inspire more of you to add them to your summer gardens.

Blue-Eyed African Daisy (Arctotis grandis)

This cottage-garden annual from South Africa produces silky white flowers with silvery mounds of foliage and stems up to 2 feet or more in height. The boss of bluish-violet disk flowers surrounded by distinct yellow bands is really quite dazzling. Put seedlings out in late April and they will quickly form stalwart clumps that bloom like blazes all summer long. This plant is not usually sold at garden centers, but is often available through mail-order catalogs. You can easily start it on a windowsill, much as you would tomatoes from seed; just don’t start the seeds much before late March. Cape daisy (Arctotis fastuosa ‘Zulu Prince’) is quite similar, but is an even more strikingly banded flower with similar cultural needs.

Iceland Poppy (Papaver nudicaule)

Poppies have long been a mainstay of cottage gardens. The genus is quite large, and many poppies in it merit a spot in your garden. Most poppies easily establish from seed, and many varieties are sold commercially. I’m especially fond of Iceland poppies, which effectively brighten Colorado ski towns in summer but aren’t as heat tolerant if planted at lower altitudes. If you grow Iceland poppies, you can expect a tremendous show of white, pink, orange, yellow or nearly red from early spring well into the summer months. If the bed is shaded at the height of summer, some will even perk up and bloom again in the cooler fall months.

Prairie Aster (Aster tanacetifolia and Machaeranthera tanacetifolia)

Most of us think of asters as perennials that bloom in autumn. There is, however, a tansy aster found on Colorado’s Great Plains that must be one of the best native wildflowers to introduce into a xeriscape or perennial garden. The plants germinate in early spring and the first purple flowers appear in June. In fertile soil with a little water, these asters make a spectacular show with dozens of enormous daisy heads of luminous lavender with bright-yellow disk flowers. (In nature, they’re much more delicate and modest.) Obtain the seed from catalogs, as you’re not apt to find this plant in a nursery.

Nemesia (Nemesia cvs.)

Closely related to the twinspur, nemesia has developed many strains that appear to be much more heat tolerant than its wild ancestors. The perky, snapdragon-like flowers usually come in blue, purple and violet shades, but pinks and whites are also common. These can be used much like the more typical pink or red twinspur—as fillers or in containers.

Baby Blue Eyes (Nemophila menziesii)

This plant is not quite as heat tolerant as so many of the other plants listed here, but it can last for many months if planted in a cooler location with some shade. The shimmering blue flowers with white centers are mesmerizing, and provide a wonderful foil to neighboring plants in hotter colors. Easily grown from seed, baby blue eyes also can be found in garden centers from time to time.

Brown-eyed Susan (Rudbeckia triloba)

I have seen this plant spread like wildfire in a few local gardens, but the classic cottage-garden annual native to the eastern U.S. is relatively rare in Colorado gardens. A pinch of seed from a catalog—or a six-pack from a nursery—will quickly produce a mound of spectacular blooms a yard or more tall that will blaze through the summer and even the autumn months.

Dahlberg Daisy (Dyssodia tenuifolia)

I have always been amazed that this showy annual, native to the Southwest, is so rarely used in gardens. Often sold under its traditional name, Dyssodia, this plant is more accurately labeled Thymophylla. But whichever name you find, expect the little pots of starts you buy in late spring to quickly form a mound of Irish-green filigree foliage with showy masses of golden marigold-like flowers throughout the summer months. I have friends for whom this plant comes back reliably, but I have to replant it every year—something well worth doing!

White Lace Flower (Orlaya grandiflora)

Someday, I expect I’ll have a number of umbels to add to a list like this. But right now the most spectacular annual umbel I’ve thus far grown comes from my ancestral island of Crete. The white lace flower produces carrot-like flower heads on bract-like segments that resemble petals around the fringes of the blossom that are truly spectacular. This plant can be obtained from a few mail-order nurseries, and even some local growers. Wherever you get it from, get it going in your garden. I guarantee it will come back strong year after year, producing a mass of white showy flowers through much of the summer.

Twinspur (Diascia ‘Flying Colors’)

Twinspur occurs all over South Africa, but usually in a deep-salmon color not often found in gardens. ‘Coral Canyon’ is a twinspur cultivar introduced by Plant Select that is reliably perennial in the Front Range, but almost all the dozens of forms sold at garden centers are annuals. Most have trim whorled leaves and flowers like flattened snapdragons. Proven Winners introduced ‘Flying Colors,’ which blooms in many brilliant colors that continue long after the first frost. Easy, tough and amazingly floriferous, this plant is a must for containers or for filling in empty garden spots.

Drummond’s Phlox (Phlox drummondii)

I’ve grown Drummond’s phlox repeatedly for its wonderful colors and distinctive markings, but the old, nearly wild strains are heat sensitive and usually perished by midsummer. Now hybridizers have produced crosses with more heat tolerance that repeat the same breadth of color and variety of forms, and on plants that bloom reliably in the hot summer months. While not as inexpensive as a seed packet, Drummond’s phlox pays for its potted price in true flower power!

Scarlet Sage (Salvia coccinea)

There are so many perennial sages in all shapes and forms that one might not know there are a number of annual sages that deserve garden space. I would pass over the dowdy six-packs of Salvia splendens—a plant that was paired with dusty miller and once sown by the mile in municipal areas across America—and instead go for S. coccinea. This splendid plant quickly makes a mound up to 2 feet tall with masses of bright crimson flowers. This has been known to reseed in some gardens, but (alas) not in mine. Few annuals deliver a bigger punch in the hot summer months than this scarlet beauty, which hummingbirds and pollinators particularly adore.

Bloomin’ Perfect: 11 Must-Have Annuals

The senior curator at Denver Botanic Gardens shares his list of must-haves annuals.

Blue-Eyed African Daisy (Arctotis grandis)

Iceland Poppy (Papaver nudicaule)

Prairie Aster (Aster tanacetifolia and Machaeranthera tanacetifolia)

Nemesia (Nemesia cvs.)

Baby Blue Eyes (Nemophila menziesii)

Brown-eyed Susan (Rudbeckia triloba)

Dahlberg Daisy (Dyssodia tenuifolia)

White Lace Flower (Orlaya grandiflora)

Twinspur (Diascia ‘Flying Colors’)

Drummond’s Phlox (Phlox drummondii)

Scarlet Sage (Salvia coccinea)

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