Trees in Drought
By Barbara Dawson, MG, Drought Committee Member
Think about your yard. What is the most important plant there? Your vegetable garden, perennials, grass? Or, did you think of trees? In fact, trees are probably the single most important item in your yard. Trees add value to your property, keep you cool in our hot summers, provide fruit, and give birds and other animals cover.
Summers in Southern California are becoming hotter and seem to last longer into the (supposedly) cooler months of the fall. Drought remains a concern although Southern California appears to have more available water than the rest of California. Nevertheless, we must consider how to manage our yards during these hotter times with less water.
Of any plant in our yard trees are the most important element and one that needs to be a priority. Why? Trees are the longest living and as such there is a greater investment in time and effort. A vegetable garden can be established in a few months, a perennial might take months to one or two years, but a tree (depending on the cultivar) three years plus. Some slower growing, longer living trees can take five years to become established and still only be a few feet high.
Ideally, during the summer trees should be watered weekly. If a tree is in the middle of a lawn chances are it's not receiving enough water. Lawn watering is superficial. Trees require deep watering at the drip line (the drip line is the area around a tree where the canopy edge reaches). The drip line may not be close to the trunk, depending on the size of the tree. Water should be given slowly over a period of time to allow for deep absorption. Knowing how well your soil retains water would be beneficial. This also prevents surface roots and encourages deeper rooting. Drip irrigation, a soaker hose, or a plain old garden hose can be used. Younger trees may require as much as 15 gallons per week in the hottest times. More mature, well established trees require three to five deep waterings throughout the summer. Fruiting trees require consistent, deep watering to maintain the crop. Symptoms of a water deficit might be dull (looking), wilting, curled, yellow leaves, and/or smaller new leaves. Plant new trees in the cooler, wetter time of winter.
Before planting any new trees, think about its water requirement. Obviously, fruiting trees will require more
water but when planting ornamentals consider how much water that tree will use both as it grows and when it matures. There are many trees available that require little water when mature. In other words, don't buy a tree that is suited for the pacific northwest or east coast where more water is available. Some good drought, heat, and pest resistant choices for this area:
‘Red Push' pistache (Pistacia × 'Red Push')
‘Bubba' Desert Willow (Chilopsis linearis 'Bubba')
‘Desert Museum' palo verde (Parkinsonia × 'Desert Museum' )unless you are in a shothole borer prone area)
Find just the right tree for just the right location visit these trustworth interactive websites: https://selectree.calpoly.edu/ https://inlandvalleygardenplanner.org/ or https://calscape.org/search.php