Tree of the Week – Ponderosa Pine (Pinus ponderosa)

Ponderosa Pine is an evergreen tree whose name and form evokes images of mountains in the Far West and wide open spaces in the Great Plains. However, it is also native to many southwestern states plus Mexico and even Canada’s western provinces.  In the United States alone, it is native to more than 35% of the total U.S. acreage.  In addition, many of its’ seed sources do surprisingly well in most other states where it is not native. The almost universal adaptability of the Ponderosa Pine is due to the widely varied native habitats the tree can be found.  At present, either the straight species (Pinus ponderosa) or its’ interior continental variety, Rocky Mountain Ponderosa Pine (Pinus ponderosa var. scorpulorum) does very well in the Chicago area.

The mature Ponderosa Pine has a straight trunk, the lower half of which is typically free of branches. In its’ native environment a height of 100 feet can be reached, but 40 to 60 feet tall is more realistic in landscape settings. Mature crown width can be 25 to 30 feet. Needles are dark green to yellow-green, and 5-10 inches long. Typically, the straight Ponderosa Pine species has the longest needles. The Pine cones are pineapple shaped, prickly and about 4 inches long. Seeds mature in two seasons and winged seeds are released from August through September.

Young Ponderosa Pine trees possess scaly-gray bark that turns black over time. As trees mature, the bark thickens and breaks into large, flat, yellow-brown and scaly topped plates that are separated by deep furrows. Older Ponderosa Pine trees have a characteristically yellow bark and are often referred to as “Yellow Pine”. The bark and fallen needles have a pleasing fragrance of vanilla or butterscotch, especially when baking in the hot sun.

Ponderosa Pine trees grow in USDA Hardiness Zones 3 through 7.  It grows best in deep, well-drained loam soils, but they can also tolerate sandy soils. The root system can be shallow to deep rooted, depending on the soil type. Often the Ponderosa Pine develops taproots, which are long roots that will reach moisture deep underground. Soil pH ranges of 6.0 to 8.0 are adequate for growing Ponderosa Pine trees. It can tolerate some soil salinity. The Ponderosa Pine is extremely drought-tolerant. Insect and disease pests are normally not a serious problem for the Ponderosa Pine, if it’s sited properly. Although full sun is needed for best growth, it can tolerate a partial sun exposure, but will not have as full a canopy.

The Ponderosa Pine is a great substitute for the disease and insect prone Austrian Pine. Its’ form and appearance is somewhat similar, especially the Rocky Mountain form of Ponderosa Pine. The Ponderosa Pine is excellent for many landscaping situations, including private and public grounds, creating windbreaks and privacy screens.

Ponderosa Pine is available in most local nurseries, although not nearly as available as the Austrian Pine. Hopefully, that will change as its’ reputation of reliability becomes more well-known.  Currently, the Ponderosa Pine straight species and the varied sources are not normally distinguishable at Garden Centers. In addition, the geographical source is not usually known. That could change if demand for the different species develops. Although specimens have been growing and thriving in the Midwest for many years, Ponderosa Pine has had an undeserved reputation of being un-adaptable. Inspecting the existing Ponderosa Pines that are thriving in our environment will ease any concerns. The Ponderosa Pine tree and its varied sources deserve to be an additional evergreen component of our “diversified urban tree species planting list”.

Harold Hoover

Kramer Tree Specialists

Board Certified Master Arborist  IL-1478B

 

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