Pine trees are native to many parts of the U.S. and naturally tolerate dry conditions and poor soils. In dry regions, they may receive no moisture for as much as six months. In a landscaped yard, providing water every 10 days during dry periods improves the tree's appearance and reduces the chances of disease and insect infestation.
Physical Effects of Drought
During drought, pine trees may seem unaffected the first year. During the second year of drought, mature pine needles turn yellow. If dry conditions continue, the tree may eventually drop needles and die. Drought-stressed trees are vulnerable to infestations by pine beetles. The pine beetles bore into the bark where they lay their eggs. The larva feeds on the interior portions of the tree, eventually killing it. If the needles turn red, the pine tree is dying and cannot be saved.
Water pine trees at least weekly immediately after planting and regularly during the first summer. As the trees become established, they need less water. Unless conditions are very dry, they may need no supplemental water at all once mature.
Growing conditions determine how long a pine tree can go without water. Because clay soils hold water well, pine trees growing in them don't develop deep roots, leaving the trees susceptible to damage during dry conditions. Pine trees growing in sandy soils, which lose moisture quickly, develop deep roots and are better adapted to drought. Trees growing in low woodland areas tolerate drought better than those growing in exposed mountain areas. In a landscaping situation, plant pine trees in well-drained, loamy soil. Mulching the area with 2 to 3 inches of wood chips conserves moisture.
Choose varieties that grow naturally in your region when selecting pine trees for your yard. These trees grow well with little help from you and tolerate local variances in weather and moisture levels better than non-native trees. Provide growing conditions similar to those the tree experiences in its native setting. For example, don't plant Ponderosa pines, which have low to moderate water needs, in a wetland setting.