What's Blooming: The Rock Garden

Clematis and pasque flowers blooming in the Rock Garden

What’s Blooming: The Rock Garden

by Bryan Fischer, Horticulturist, Gardens on Spring Creek

Heralding the opener for a slow, cool spring, the Rock Garden is finally coming into bloom. Wet, cool snows and frigid temperature plunges this spring have kept many plants from breaking dormancy and have slowed the bud development of others. In fact, many plants on our grounds are almost two weeks behind their normal bloom times.

This aside, the spring is shaping up to be a great one for the diversity of blooming plants on our grounds. Members of the Ranunculaceae seem to have particularly enjoyed the chilly weather, with pasque flowers (Pulsatilla spp.) of several species reveling in the weather conditions more reminiscent of their mountain origins than our occasional jumps to 80 degrees or higher the way our last few springs have been.

Pulsatilla vulgaris, or common pasque flowers in bloom

Pulsatilla vulgaris, or common pasque, is the most visible of these on the grounds. Self-seeding liberally around the Rock Garden, particularly on east-facing aspects, the species is producing swaths of two- to three-inch royal purple blooms with yellow centers consisting of dozens of fuzzy anthers. Though not native, this species is arguably the easiest to grow in the genus, as it tolerates transplant better than many of its near relatives.

Clematis hirsutissima var. scottii

One near relative that does transplant reasonably well, albeit slow to establish from transplant, is our native Clematis hirsutissima, as well as it’s variation, Clematis hirsutissima var. scottii. Commonly called sugarbowls or Scott’s sugarbowls, these native clematis form neat two-foot mounds rather than the large, ungainly vines we often associate with this genus. These plants’ fuzzy, finely-cut foliage is breaking ground in many cooler places of the Rock Garden now, and the blooms of these plants are already popping on the garden’s warmer aspects. Velvety, nodding flowers that mirror those of pasque flowers in shape but hang over these plants by the dozen give the plants a quirky, yet surprisingly polished look. Clematis hirsutissima offers more finely-textured foliage and a slightly earlier bloom, and the foliage of C. hirsutissima var. scottii is less hairy.

Clematis seedhead

One of the most appealing features of these unique clematis are their seedheads, which look a bit like truffula trees from the Dr. Seuss book “The Lorax”. Appearing with one inch long, fuzzy tails in dense clusters at the top of each flower stalk, the seedheads of these plants glow with backlighting in the morning and the evening. I aim to site these plants where they will receive east or west lighting, so as to take advantage of this trait and maximize seasonal interest.

Expect to find these blooms for the next three weeks in the Rock Garden, with seedheads lasting for weeks more.

Hornworms by Brionna McCumber

Gardeners in Colorado may find large green caterpillars with an iconic horn on their plants every summer—these are hornworms! Tobacco hornworms ( Manduca sexta ) feed on common garden crops, often leading to conflict with humans. These very hungry caterpillars are defoliators, damaging plants such as tomatoes, peppers, potatoes, and eggplant. While the caterpillars use crops as a food source, which could be seen as negative, the moths provide a critical step in reproduction for the plants via pollination. Carolina Sphinx Moths ( Manduca sexta ), also called Hummingbird moths, are the adult form of hornworm s. They are known for their unique ability to hover mid-flight. Combined with the use of a special elongated proboscis, these moths are especially important for plant species with long tubular flowers that other pollinators cannot access or pollinate. The Gardens on Spring Creek Butterfly House wants to highlight the importance of these specialized pollinators in our...

Winter Watering by Bryan Fischer

O ne of the brightest spots of living on the Front Range of Colorado is its winters. With more than 300 days of sunshine annually, we seldom see extended periods of the grey, chilly, precipitating skies common in so much of the country. It’s not unusual for daily highs to make it above 50 degrees. Much of this we have our elevation and distance from an ocean to thank – our sunlight is more intense than at sea level and our humidity lower, resulting in greater warming during the day compared to regions of similar latitude to our east or near a coastline .  Unfortunately for many landscape plants, however, that same day-night temperature differential spells trouble when paired with our lack of soil-insulating snow cover.  The resulting environment of warm days, frequent wind , and intense sun increases water demand, while low humidity saps the soil moisture reserves that our limited precipitation may provide. As a result, our landscape plants are predisposed to dehydration-indu...

Conifers: Pining for Something Different by Bryan Fischer

Evolving considerably earlier than flowering plants (angiosperms), conifers represent a long-lived and successful lineage of trees classified as gymnosperms. Gymnosperms were among the first true seed-bearing plants and evolved before specialized pollinators existed, so they are typically wind-pollinated. Seeds on these plants are produced between or on scale-like structures (think pine cone scales), rather than in fully enclosed structures, like tomato fruits. Gymnosperm, in fact, is Greek for “naked seeds,” so just imagine what that might imply for the origin of the word “gymnasium” … Long-lived, adaptable and attractive year-round, conifers represent a silver bullet of sorts for our Colorado gardens. Sadly, the overuse of just a few species and cultivars of these plants has given them a bad name. Don’t be put off – judicious use of conifers makes perennial plantings “pop” and provides structural bones during the fall and winter months. Below, find a selection of underused, adap...

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