Tips on Growing Ponderosa Pine

Location

• Selecting a favorable growing site is crucial for successfully growing ponderosa pines. No matter how well young pines are maintained and cared for, they will perform poorly if the location is not suitable for them. Ponderosa does not tolerate saturated soil. Heavy, clay-based soils tend to harbor large quantities of moisture compared to loamy and sandy soil. They grow better in medium- and coarse-textured soil compared to fine-textured media, according to the U.S. Forest Service. Ponderosa thrives in slightly acidic soil, with a pH level between 6.0 and 7.0, but it does not grow well in alkaline soils.

Site Preparation and Transplanting

• Plants and weeds must be completely removed from the growing site before planting ponderosa seedlings. Controlling the growth of weedy plants is important for at least several years after planting young pines. They can force out competition on their own once their roots spread out. Individual pines should be spaced roughly 10 feet apart from one another and at least 20 feet away from established trees to prevent them from competing with the young pine trees for moisture and nutrients.

Pest Management

• Monitoring ponderosa for pests throughout the spring and summer can help prevent a serious infestation. There are over 100 known insect species that damage ponderosa pines, according to the U.S. Forest Service. Bark beetles, weevils and moths are among the most common insect threats. The pine tip moth (Rhyacionia spp.) and gouty pitch midge (Cecidomyia piniinopis) feed on emerging growth, like buds and new stems. Some other pests, like the pandora moth (Coloradia pandora), consume large quantities of ponderosa foliage, causing aesthetic damage and decreased plant vigor. Insect damage is rarely deadly to mature trees, but it can leave them vulnerable to diseases and other problems that could produce fatal symptoms.

Disease Control

• It is especially important to check for diseases consistently in large or commercial plantings of ponderosa. Some pine diseases cause severe damage and can spread to neighboring trees quickly. Foliar diseases, like fungal leaf spots, can kill and discolor patches of pine foliage. These diseases cause superficial damage and rarely affect the plant's survival. Affected areas should be pruned, and all fallen debris must be removed before winter to prevent these fungi from completing their life cycle and emerging the following year. More serious diseases, like root rots, are more difficult to control. These ailments, like the fungal Armillaria root rot, are caused by soilborne pathogens that exist naturally in some locations or are introduced by contaminated tools or soil. Young trees planted near infected trees can be transplanted to clean soil in another location, but there is no way to reliably prevent them from contracting the disease if the pathogen is present.