Soil and Location
In nature, both species of pinyon occur on a wide variety of soil types. Single leaf pine is typical on well-drained, shallow, low fertility soils. Rocky Mountain pinyon grows on both shallow and deep soils of low fertility. In your landscape, almost any kind of soil is suitable as long as there's good drainage. Don't locate either species where water accumulates, but locate them on slopes or on mounds where water drains away.
Water the newly planted pinyon immediately and thoroughly. During the first year it's in place, water it regularly, especially during summer months to establish a good root system. A suggested watering protocol is about once a month in September through May and twice a month from June through August. Established trees need little extra water except during drought years, when pinyons should receive a deep monthly watering in winter and early spring. Overwatering can cause root rot and perhaps even death.
LIght and Growth Rates
Both kinds of pinyons require full sun to grow well. Growth is slow, with trees capable of adding about 12 inches a year to their height. Don't try to hasten tree growth by extra watering and fertilizing, which can weaken or kill the pinyons. When grown from seed, either species of pinyon take about 25 years to reach a size where they will start producing cones. If you plan to grow pinyon pines to harvest their edible seeds, plant more than one pine for cross-pollination.
With their slow growth rate, pinyons don't need much fertilizer. The University of Nevada Cooperative Extension considers it unnecessary to fertilize or irrigate established pinyons, except if they have been damaged. Mary Irish, writing about pines in her book, Texas Getting Started Garden Guide, recommends fertilizing young trees once in the spring, and not fertilizing mature plants. The Lady Bird Johnson Wildlflower Center suggests giving Rocky Mountain pinyon a fertilizer with a 3-1-2 N-P-K ratio fertilizer three times a year. Use a product such as 12-4-8 applied at the rate of about 3 tablespoons per 10 square feet. Scatter the fertilizer evenly around the dripline of the tree and water it in well.
Pruning and Pests
Low-maintenance pinyons need pruning to shape the tree when it is young or to remove dead or damaged branches on older trees. Before pruning, clean the pruning tools with a cloth soaked in rubbing alcohol to prevent spreading disease. Generally free of diseases and pests, the pinyon can be infested by a type of small engraver beetle called the pinyon ips beetle (Ips confusus). It burrows beneath the bark of pinyons and can cause tree death. Beetles normally don't occur in healthy trees. To avoid ips beetle infestations, avoid damaging the tree and its roots or allowing it to become drought-stressed. If you prune landscaping plants, don't stack the freshly cut branches near pinyon trees, since newly cut wood attracts the beetles as a breeding site.