LONG-BLOOMING PERENNIALS FOR COLORADO
At our nursery it is not unusual for people to ask us for plants that “bloom all the time”. And we have to admit that most perennial plants only have one sexual cycle per season, and that for a garden to have truly continuous bloom, we must include spring-blooming plants, summer-blooming plants and fall-blooming plants.
In addition, there are a few other important issues to mention regarding the quest for long-blooming perennials. One is that “long-blooming” should be included in the larger subject of “long seasonal interest” which can include foliage color, interesting textures, contrasting forms, evergreen and ever-silver, sculptural elements, fall color, and attractive fruits, seeds and bark. It is also relevant that long-blooming can sometimes mean short-lived because the plants’ strategy to produce a lot of flowers resulting in a lot of seed, can exhaust the plants.
Also, as the country song goes, “Spring would be a dreary season, if there was only Spring.” Change is exciting; only if some things stop blooming does visual space open up to appreciate the emergence of a new bloomer. And opening to seasonal change helps us to internalize Nature’s wisdom of cycles, so we don’t expect constant blooming from ourselves and others. And lastly, bloom time can be lengthened with cultural methods such as watering adequately during bloom time, increasing soil fertility for some species, and not for others; and removing spent flowers before seed takes energy from the parent plant.
However, there ARE perennials that have exceptionally long bloom times. Here are five good ones that are easy to grow and that thrive in the Denver metro area:
Erodium chrysanthum, Yellow Storksbill, makes a compact mound of lacy gray-green leaves, 6″ high and 12″-24″ in diameter. The typically pale citron-yellow, five-petaled, geranium-like flowers rise a few inches above the foliage on thin stems. The spring bloom is strongest, followed by some reblooming the rest of the summer. Supposedly there is a female form with sulfur yellow flowers that blooms even more freely. This is a very drought tolerant plant that although it is not well known, has a history of dependable success in the Denver area. Yellow Storksbill is also an elegant and well-behaved plant for the front of the border, along a path or as a specimen. Its gentle texture and subtle color makes it a good foil for bolder colors and forms such as Scabiosa caucasica (Blue Pincushion Flower and Aquilegia chrysantha (‘Denver Gold Columbine’)
Plumbago (Ceratostigma plumbaginoides) is a tough and drought tolerant ground cover that blooms a very long time from summer into fall, and then dazzles us with deep red fall foliage color. The flowers are an intense dark blue. The attractive shiny green foliage disappears in winter and doesn’t return until early May. This is a long-lived and dependable plant in a variety of soil types and in part-shade or full sun. It grows 6″-10″ high and spreads 24″-36″ or more into drifts that can weave with other plants. It has exceptional value underneath trees in dry shade.
Geranium ‘Rozanne’ was chosen as the 2008 Perennial Plant of the Year because of its large violet-blue flowers that bloom “continuously” from late spring to mid fall. The flower is 2 ½” in diameter with purple-violet veins and showy white centers. It can grow 12″-24″ high and wide and its dark green leaves turn red in the fall. It was discovered in England, but the Perennial Plant Association chooses plants that are adapted to a wide range of climates and conditions, and it is claimed to be heat and drought tolerant. It has been tested in the US and is said to have one of the longest bloom times of any of the hardy geraniums. Like most hardy geraniums, ‘Rozanne’ has no serious pests and requires little maintenance except to shear it 3″ in August. It could even be a good candidate for a container.
Chocolate Flower, Berlandiera lyrata, is a native of southern Colorado and the Southwest that blooms from early May through the summer. Its bright golden yellow daisy flowers really do perfume the air with the fragrance of chocolate. This pest-free plant grows to 12″-16″ high and can be 18″-30″ wide. It withstands heat waves, full sun, drought and a variety of soil types. However, Chocolate Flower does not stand over-watering, so if the flowers droop in the afternoon, understand that this reflex is a natural reaction, not a cry for water. The seed heads are ornamental and can lead to some self-seeding. This is a good plant for a xeriscape, shrub border or meadow.
Papaver croceum is a very attractive form of Iceland Poppy, Papaver nudicaule, which has naturalized in the Colorado mountains around old mine sites. The form available locally blooms from early spring through the summer with 2″ bright lemon yellow, cupped poppies on wiry stems 12″-16″ tall. The gray-green hairy foliage makes an attractive evergreen rosette. This lovely and delicate flower is drought tolerant, adaptable and even holds up to the wind. It can be grown in full sun or part-shade and can form charming colonies if allowed to self-sow.
LIST OF LONG-BLOOMING PERENNIALS
Gaillardia aristata – Indian Blanket Flower
Oenothera caespitosa – Tufted Evening Primrose
Oenothera macrocarpa – ‘Silver Blade’ etc
Mirabilis multiflora – Desert Four O’Clock
Calylophus hartwegii – Sundrops
Viola Corsica – Corsican Viola
Hymenoxys scaposa – Sundancer Daisy
Datura wrightii – Sacred Datura, Angel’s Trumpet
Gaura lindheimeri – Whirling Butterflies
Linum flavum - Golden Flax
Penstemon rostriflorus – Bridges’ Penstemon
Penstemon richardsonii – Richard’s Penstemon
Penstemon mexicale ‘Red Rocks’
Penstemon pinifolius – Pineleaf Penstemon
Saponaria ‘Max Frei’- Max Frei Soapwort
Argemone polyanthemos – Native Prickly Poppy
Callirhoe involucrata – Prairie Winecups
Diascia integerrima ‘Coral Canyon’
Salvia greggii – ‘Furman’s Red’ & ‘Wild Thing’
Glaucium acutidentatum, G.flavum etc
Sphaeralcea – the taller species