Dwarf conifers can solve problems

By Ted Schaaf
Gardens on Spring Creek

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Many of us have made the mistake of planting that cute 3-foot tall blue spruce in a prime spot in the center of the yard. As years go by, the tree begins to take over not only the yard but the house as well.

Nurserymen have responded to this problem by offering many new varieties of dwarf evergreens. These trees help define the structure of a garden.

The term dwarf can be a bit misleading. Generally a dwarf conifer will have a mature height of less then 12 feet or is so slow growing, about 1 inch per year, that the garden is long gone before the tree reaches its mature size. Because these gems of the plant world are expensive to propagate and grow so slowly, a higher price tag should be expected. Most reputable nurseries will, however, offer a one- to two-year guarantee.

Site preparation

To be their best, most conifers prefer well-drained and somewhat sandy soil. Think of where our native evergreens grow. Most can be found near the top of some type of slope. We can duplicate these slopes in our own yards by creating berms. Berm mixtures should contain an amended topsoil and a breeze material, which is finely crushed granite. This will give the soil the grit it needs for proper drainage.

A good rainfall or irrigation system may not provide enough water to saturate the root ball of your dwarf conifers. So after planting, be sure to keep them well watered during the establishment period. Even though many of these evergreens will require little water after they are established, they need at least two or three years before they can be weaned off the hose. Be sure to build up the soil around each tree so that water will soak into the root ball and not drain off.

Selections

One of my favorite dwarf conifers is the dwarf Arizona fir Abies lasiocarpa var. arizonica 'Compacta'. As the name implies, this tree is native to Arizona. It also extends into northern New Mexico. It can be identified by a grayish white bark that is contrasted well by blue-green needles. Unlike spruce needles, fir needles are flat making them a joy to caress.

At the Gardens on Spring Creek, the dwarf Arizona fir is growing on top of a berm in the Children's Garden. It shows no sign of browning, despite its exposure to harsh winters. The mature height for a dwarf Arizona fir is around 12 feet with a 6-foot spread. It is an exceptional evergreen that is currently underused in home landscapes.

Great improvements have been made in the popular mugo pine. The old varieties were not always dwarf. I know this from experience. At a former home, an aging mugo pine growing near the garage was clearly larger then the garage itself.

Pinus mugo 'Mops' is a low, mounded, bonsai-like structure. It is a true dwarf that will grow to approximately 2 feet tall by 4 feet wide. The needles are short, about 1 inch long, and are grouped together in bundles of two. They retain their green color throughout the winter. If you want to keep your mugos smaller than 1 foot, simply remove the early spring candles. These are the new spring growth. The candles are ready to remove when they can be easily snapped off. Mugo pines have adapted well to the poor soil types found along the Front Range and are drought tolerant once established.

Of course we in Colorado must pay tribute to our state tree, the Colorado blue spruce. As mentioned earlier, however, these trees don't fit today's small urban lots. A new form called Picea pungens 'Saint Mary's Broom' is an exceptional globe shaped spruce that has been grafted onto the rootstock of our native blue spruce. The result is a slow-growing spruce with bright blue needles. Its branches remain tight, meaning they will not flop. Expect a tree around 3 feet high by 3 feet wide. This variety is much slower growing than the more popular Montgomery spruce and is less likely to have any tendency to grow a main leader. It is best planted in a location with full sun and needs moderate moisture for best results.

Our gardens of today are no longer specialty gardens. The new trend is toward gardens that multi-task. These types of gardens combine different plants such as herbs, roses, ornamental grasses, perennials, woody plants and yes, even vegetables. Dwarf conifers make perfect companions to other ornamental plantings.

These gardening and landscaping columns will continue through October. Happy gardening.

Ted Schaaf is the horticulturist for the city's Gardens on Spring Creek, located off Centre Avenue about one-half mile south of Prospect Road in Fort Collins.