10 Tips for Tree Care During a Drought
Unlike a lawn, losing a mature tree is a tragedy that may take decades to replace. Trees play an important role in a water-wise garden and the drought is adding stress to many. While they do need more water than your average shrub, the reality is that shade provided by trees helps prevent water evaporation affecting other plants by cooling down soil and can even reduce energy consumption inside the home.
In addition, trees can raise property values, provide insulation from street and other noise and help clean the air. But taking care of them during a drought does require extra care and prioritization. Here are tips for tree care during drought to make sure that your beautiful trees survive.
1. Prioritize Watering
It takes years—sometimes decades—for trees to reach mature heights. Because replacing trees can require a lot more expense and patience than a shrub or annual, you may want to delegate a larger amount of water toward their preservation. The lawn should receive the lowest priority, in fact doing so is a great opportunity to replacing it with artificial grass or native plants.
2. Check All Trees for Stress
It may take years for drought stress to appear or it can happen quickly so always keep an eye out for it.
It’s important to distinguish normal leaf drop from leaf drop that is due to stress. Normal leaves that drop are typically uniform in color. Leaves that drop due to lack of water have brown, wrinkled, curled and/or crispy edges. You may also notice smaller-than-average-sized leaves dropping from the tree or dead leaves remaining on the tree.
The tree itself may have visibly wilted leaves or branches that have a dieback of branches. Trim away stressed branches so that the tree isn’t expending energy inefficiently. This also will improve branch stability and overall structure.
A stressed tree is more susceptible to disease and pests so it is important to vigilantly monitor both. And, refrain from fertilizing trees during drought as not to encourage new growth that will need to be sustained by more water.
This is an extreme example of drought stress in citrus trees planted in Northern California.
3. Check the Soil
Use a shovel or screw driver to to determine how dry the soil is. If it is too difficult to push either one into the dirt (as is often the case with clay soil), it’s time to water. If the dirt unearthed at about a 6-12″ depth is soft, dry or flakey, it’s time to water. Perform soil checks several times per month to ensure that your watering strategy is sufficient. If it’s moist, then wait to water.
4. Water the Right Way
With current water restrictions limited the days of the week and amount of time irrigation can be turned on, a tree on a drip line or in an area with low-flow or even full flow sprinkler heads isn’t usually going to be enough.
Those with drip irrigation may want to consider spiraling a soaker hose multiple times starting a few feet out from the base of the tree and ending at the edge of the drip zone or critical root zone, which can be estimated as the area underneath the tree’s canopy. Whatever method you choose, keep an eye out for run-off.
5. Water Deeply
The goal of any of the above watering strategies is to water less frequently but more deeply. It is also extremely important to mitigate run-off. It’s estimated that 90% of a trees roots are quite small and actually within about 12″ of the soil’s surface. They also anchor the tree in place as well as conduct much-needed water and nutrients to where they are needed most.
6. Use Repurposed Water
In a perfect world, soaking the tree roots with a large bucket or hose would do the trick but alas, this isn’t inline with current regulations. What you can do is repurpose large quantities of water and use it to nourish trees. The best way is to keep a bucket near the shower and fill it with cold water that would otherwise go down the drain while you wait for hot water to appear. Then, go dump it on your trees.
7. Mulch the Drip Zone
Adding a layer of mulch to the tree’s drip zone can help cool the area, lock in moisture and prevent evaporation. Use wood chips, bark, leaves or even pine needles. Avoid stones as they absorb heat and increase temperature around the tree. Keep mulch about 6″ or so away from the tree’s trunk.
Lawns compete with trees for water. If there is lawn covering a tree’s drip zone, swap it out for mulch.
8. Water at the Right Time of Day
Trees typically replace water lost during the day after sunset and before the sun rises. Watering during these times also helps eliminate evaporation do to sunlight and heat.
9. Keep Tree Type and Location in Mind
Tree care also largely depends on the age and type of tree. Young trees have less established roots and will need easy access to water. They will need more frequent watering until roots are established. Deciduous trees require more water during late winter and early spring as new buds and leaves form.
Mature trees planted in direct sunlight as well as those next to driveways, streets and other heat absorbing materials will also require more water and monitoring than others.
10. Plant the Right Trees
Trees native to your area usually require the least amount of water but there are many other drought resistant options. In Southern California, this means oaks, manzanita and red bud, to name a few. Mediterranean trees such as fruitless olive, Italian cypress and acacia trees also do well here. Museum Paleo Verde trees are popping up all over San Diego and Jacarandas (pictured above) are another common choice. We’ll put together a list of common drought resistant trees for Southern California next week.
If trees are still showing signs of weakness after implementing strategies mentioned above, do not hesitate to call an arborist for advanced assistance. A tree is a precious resource that is worth saving.
What are your best tips for tree care during a drought?
Photo credits: Flickr/graeme; Flickr/usdagov; Flickr/Port of San Diego, Creative Commons, 2.0