Gardenguide: A marriage of water, stone, and plants - news and tips on gardening in Western states

Sunset, Oct, 1999 by Marcia Tatroe, Jim McCausland, Lauren Bonar Swezey, Dick Bushnell

A prizewinning design blends colors and textures on a Colorado hillside

* After construction of an addition left a gaping hole in the backyard of their home in Cherry Hills Village, Colorado, the owners sought help from landscape designer Robert Howard of Boulder. He met the challenge by transforming the unsightly hillside into a lush mountain canyon with a meandering watercourse. Howard's engaging design won a merit award for residential garden design from the Associated Landscape Contractors of Colorado.

The recirculating stream is punctuated by a series of waterfalls and small pools. Slabs of native red flagstone form steps that lead along the stream, echoing its graceful curves.

Upright spikes of yellow flag irises, white Siberian irises, and ornamental grasses stand in elegant contrast to large, round boulders along the streambed. Perennial ground covers scramble around the rocks for an exuberant look that requires little maintenance. In the photo above (taken in mid-June), native bluebells (Campanula rotundifolia) brighten the foreground, while patches of pink Dianthus deltoides 'Zing Rose' highlight the top of the walk.

All of the plants were set out in autumn. Howard advocates fall planting for several reasons. Plants get partially established before freezing weather arrives, then fill in quicker when the growing season resumes in spring. The cooler temperatures reduce the plants' water needs. Gardeners also get a break from weeding until the following spring.

Select plants for the new millennium

* Each year since its inception in 1997, the Plant Select program cosponsored by Colorado State University and Denver Botanic Gardens has been responsible for introducing worthy new plants to intermountain gardens. Five more winners made the Plant Select honor roll for the year 2000. They take full sun or partial shade. Look for plants bearing the Plant Select tag at participating nurseries next spring.

'Coral Canyon' twinspur (Diascia integerrima), a 15-inch-tall perennial, is topped with coral-pink flowers from June through frost. Give it moderate water below about 7,000 feet.

'Pawnee Buttes' sand cherry (Prunus besseyi), a ground-cover form of the Rocky Mountain native, stays under 18 inches tall but can spread to 6 feet. Fragrant white flowers rise above its shiny green leaves in April, black cherries follow in summer (birds love the fruit), and the leaves turn red and purple in fall. It can grow at elevations up to 9,000

'Prairie Jewel' penstemon (P. grandiflorus) is the showiest of the northern Great Plains penstemons. Its blooms come in lavender, rose pink, violet purple, and white. Plant this 2-foot perennial in full sun in a well-drained spot.

'Princess Kay' plum (Prunus nigra) is bedecked with double white flowers in spring, a neat green crown in summer, and spectacular red foliage in autumn. This tree grows fairly quickly to 20 feet tall and 15 feet wide.

'Spanish Gold' broom (Cytisus purgans) develops into a 6-foot-wide, 4-foot-tall mound of green stems covered with a mass of yellow flowers every spring. This shrub does well in the southern Rockies at elevations up to 8,000 feet.

How to store dahlias for winter

* When dahlia foliage is fully withered and the plants are dormant, it's time to dig up the tender tubers and store them for winter. (In frost-free areas, you can leave tubers in the ground through winter. But to ensure superior flowers, most gardeners dig and lift their dahlias each year.) Follow these steps.

1. Cut back flower stalks to within 4 inches of the ground.

2. Carefully dig a 2-foot-diameter circle around each plant (photo A).

3. Using a spading fork, gently pry up the clump of attached tubers (photo B).

4. Shake off loose soil (photo C). Let the clumps dry in the sun for several hours.

5. Before storing the tubers, label them so you won't mix up the different varieties. Attach a tag to record details such as variety name, color, and comments ("'Tequila Sunrise', caramel-orange, cactus-type, 7-inch bloom, superior foliage," for example). Or write the variety name directly on the tuber with an indelible pen.

6. To prevent mildew or rot, dust the tubers with sulfur.

7. Fill nursery flats, wood boxes, or paper bags with dry peat moss, clean sand, sawdust, vermiculite, or perlite, then bury the tubers in single layers inside, leaving labels exposed (photo D). Store the containers in a cool (40 [degrees]-45 [degrees]), dry place.

8. In the spring, two to four weeks before planting time, divide the tuber clumps. Cut the clumps apart with a sharp knife, making sure that each tuber is attached to a portion of stalk and shows a visible growth bud.

Weave a wreath of rose hips

* Left uncut, rose blossoms develop into seed pods called hips. Species such as Rosa rugosa and many old garden roses are especially prolific producers of hips in shades of red or orange. To enjoy their beauty all winter long, garden writer Georgeanne Brennan weaves hip-laden canes into wreaths. Here's her method.

1. Choose a relatively thornless rose with hips that grow every 4 to 6 inches along the cane. Cut off three or four canes, each about 3 feet long.