Rock gardens rock

By Ted Schaaf
Gardens on Spring Creek

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Our state has some of the best rock gardens in the country. Nature inspires us to bring what we experience in the mesas of Colorado into our own back yards--on a much smaller scale, of course, than say the Garden of Gods in Colorado Springs, Red Rocks Park in Morrison, or the flatirons in Boulder.

These Colorado landmarks are nature's rock gardens. They provide an ecosystem that supports some of Colorado's most diverse plant and animal communities.

The bones

The bones of every rock garden are the rocks themselves. Visiting a rock supplier is one of my favorite excursions. I always have considered myself a bit of a rockhound. Just ask my wife.

The most common rock used in rock gardens is the moss-covered granite, but don't limit yourself. Many different types of sandstone come in a variety of exciting colors.

The rocks need to be large enough to be considered boulders. I like to use this rule: If you can lift the rock yourself it's too small. Keep in mind that these rocks need to be planted into the ground for a more natural look. Plant rocks with at least 1/3 of the rock buried into the ground. Placement of the rocks is in itself a work of art. Position rocks with the idea of creating planting pockets. A rock mulch, such as pea gravel, is the icing on the cake.

The best location for your rock garden is a natural slope in your yard. If one doesn't exist, then creating berms is your next option. Berms allow you the ability to create planting environments that more closely match the plants you're using. For example, place dryland plants on the hot south side of the berm. Plants needing more moisture can be planted on the cooler north side. A soil mix that works well is two-thirds amended top spoil and one-third breeze (finely crushed granite). This mix will provide the needed grit that many rock garden plants enjoy. It will also provide the necessary drainage that is key to successful rock gardening.

Plant selection

This is where the fun begins. Most rock garden plants are perennials. They are usually low growing and are clumping in nature. Some of my favorites include sedums, especially the variety 'Angelica'. Angelica has bright yellow foliage that turns orange in the fall. Dianthus 'Firewitch' is a standout with its steel blue foliage. Its bright pink flowers appear continuously between early spring and mid-summer. Alyssum montanum is a smaller version of the popular Basket of Gold Alyssum. Even when it is out of bloom, its gray foliage adds interest. Its cheerful flowers announce spring is here. A great evergreen plant is the pine-leaf penstemon. Its red and yellow trumpet-shaped flowers will attract humming birds. The ice plant or Delosperma, named for flowers that shimmer as though coated with ice, continues to grow in popularity. Although many new varieties have been introduced over the years, my favorite is still the yellow ice plant variety 'Gold Nugget'.

Woody plants add structure to your rock garden. I've been very excited lately about all the new types of dwarf evergreens. They look at home with the other rock garden plants and help provide balance to the large boulders used in your rock garden. Each variety provides something special.

The Montgomery spruce is a dwarf evergreen that has been available in the nurseries for years. Its classic blue-green needles add color to the rock garden. A fir that is of particular interest is the dwarf Arizona Fir. Unlike spruce needles, fir needles are flat and soft to the touch. Pines such as the dwarf Eastern white pine have soft, silver-green needles. Its silver-gray bark contrasts well with the needles.

The Gardens on Spring Creek is excited about hosting a rock garden symposium entitled, "On the Rocks: Rock Gardening on the Front Range" on April 25. A Rock Garden Tour will be held on April 26. The symposium will feature regional rock garden experts. These special events will raise funds for the construction of our rock garden, designed by Kirk Fieseler of LaPorte Avenue Nursery. Preregistration is required. Seating is limited. Please make inquiries regarding this event by calling the Gardens at 416-2486. A schedule and registration form is also available on the events page of our web site, fcgov.com/gardens.

Happy gardening!