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Water-Thrifty Pinyon Pine

By Robert Cox, Colorado State University Cooperative Extension, Horticulture

The pinyon pine doesn't get much respect in Front Range landscapes, but this may be the year it shines as a replacement for trees lost in the March and May snowstorms and as a water-thrifty native for those planning to adopt principles of Xeriscape.

Pinyon, also written as pinion or pinon, is a sturdy, relatively slow-growing pine that will grow to about 20 feet tall and wide (although some specimens may grow to 30 feet tall) and will thrive on available precipitation after an establishment period of one to two years.

The pinyon (Pinus edulis) is the state tree of New Mexico (pinon in Spanish means nut pine), and along with a few kinds of junipers, it grows on several million acres in the Four Corners states in pinyon-juniper woodlands.

The woodlands designation is used rather than forest because the trees are relatively small and rarely harvested for timber. However, pinyon nuts and firewood are in demand.

In Colorado, pinyon is found growing primarily in the western two-thirds of the state from the New Mexico border north to the Wyoming border, at altitudes of 5,000 to 7,500 feet.

Pinyon is well adapted to the 9 to 15 inches of precipitation it normally receives in its native habitat and is one of the best native plants to use in a low-water use landscapes. However, pinyons in southern Colorado and northern New Mexico have been hard hit by several dry years in a row.

As a result of this cumulative drought stress, native pinyons have been attacked and killed by an insect called the pinyon Ips beetle (For more information, see: Pinyon Ips Beetle).

While the current infestation of pinyon Ips has been most prevalent in the southern part of the state, a related Ips beetle, Ips hunteri, is attacking older, stressed spruces in the metro area.

Most landscape nurseries that dig and collect young pinyon trees in drought-stricken areas spray them with an insecticide to prevent Ips attack. (This would not be the case for trees dug and then sold along the roadside or door-to-door from trucks.)

Pinyons transplanted to the landscape are best when planted in full sun and well-drained soil, at altitudes of 7,500 feet or less. A WaterWise recommendation during the current drought is to plant pinyons that are 6 feet tall or shorter.

Plant them in hot, dry locations, on berms or slopes rather than in low spots where water collects. Mulch with 3 inches of wood chips, pine needles or similar organic material, then water the tree. Frequency and amount of water depends on tree size, exposure, soil type and weather conditions, but a general schedule might be to water mulched pinyons once a month in cooler months (September through May) and twice a month in warmer months (June through August).

Just as severe drought stresses pinyons, so does excessive moisture after establishment. Avoid planting them in lawns, except buffalo grass or blue grama. Too much water makes them prone to other insects; established pinyons that receive precipitation only generally have few pest insect problems.

Pinyon needles are 1-2 inches long, medium to dark green, and borne in bundles of two or three. Pinyon cones open up to look like a brown rose. The nuts in the cones are widely sought after by both people and animals.

However, one pinyon in a landscape is unlikely to bear nuts - the shells will be light tan and empty due to lack of sufficient pollen. Where there are more pinyon trees in an area (more pollen), cones may develop chocolate brown shells with nuts. It takes several years for pinyons to reach the size and age necessary to develop cones. Additionally, cones and nuts are not borne every year, but only in years following conducive weather and precipitation.

Pinyon trees can be planted in groups to form a screen or windbreak, or singly as a focal point in the Xeriscape garden along with yarrow, Russian sage, purple coneflower, desert four o'clock and winecups.

Photo: Judy Sedbrook

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Date last revised: 01/05/2010