While it’s important to plant new trees, it’s also important to take care of the ones that have been here for 50 or 200 years. Mature trees provide carbon sequestration, reduce energy consumption in summer, and cut air pollution throughout the year. Here are three things you can do to keep your older trees healthy—particularly your oaks.

1. Water trees in the right amounts
The number one thing you can do for mature tree health is to make sure that the amount of water supplied is appropriate for your tree. Watering your tree gradually and deeply will ensure that your tree thrives. Apply water slowly and evenly to the tree’s root zone, saturating the soil to a depth of 12-18 inches. For most mature trees, regular monthly deep watering is recommended in the absence of soaking rains. Coast Live Oaks are the exception to this as they are very drought resistant and vulnerable to Sudden Oak Death. Consult a certified arborist to learn how much and when to water specific trees.

2. Prune wisely
Mature trees need to be pruned regularly to remove dead or diseased wood and to remove excessive weight from the ends of branches. The process called “end-weight reduction” will reduce the likelihood of branch breakage and hazards. It also reduces the chance that your tree will collapse or fall over during winter storms. Make sure a trained professional, ideally a certified arborist, prunes your tree. Inadequate pruning compromises the health of trees. Whatever you do, avoid “topping” your tree—this harmful practice ruins the tree’s natural structure, starves the tree by removing a high percentage of food-producing leaves, creates openings for disease, and initiates the tree’s eventual demise.

3. Watch for pests or diseases
If your tree seems to be oozing liquid from its trunk or leaves are changing color or curling or there are small growths on the leaves, your tree is calling out for help. Watch trees carefully for foliage and bark changes to catch problems early and begin care and treatment. Have a certified arborist periodically inspect the tree for these and weak branch attachments—for its health and your safety.