No Rain and More Heat Ahead: Now Is a Good Time to Give Your Trees Supplemental Water
By Beaver Arborist – Serving Santa Barbara Since 1979
Santa Barbara has gone a long time without meaningful rainfall, and warm weather is continuing. After months of dry conditions, many mature trees throughout our area are relying on increasingly limited soil moisture.
Even trees that appeared healthy through summer can begin showing signs of drought stress after an extended dry period.
This is a good time to give many of our mature landscape trees some supplemental water.
Why Water Now?
Santa Barbara's Mediterranean climate naturally gives us a long dry season, but extended periods without rain can gradually deplete moisture available to mature trees.
Combine that with warm temperatures, southern exposure, compacted soils, reflected heat from hardscape, and inadequate irrigation, and trees can enter fall under considerable stress.
The effects aren't always immediate.
Watch for signs such as:
- Thinning or increasingly sparse foliage
- Premature leaf drop
- Smaller-than-normal leaves
- Browning or scorching
- Dead twigs and branch dieback
- Reduced growth
- General loss of canopy vigor
When conditions remain hot and dry, supplemental watering can help many mature trees maintain vigor until seasonal rainfall returns.
Your Irrigation System May Not Be Watering Your Trees
One of the most common misconceptions we encounter is: “My irrigation is running, so my trees must be getting enough water.”
Unfortunately, that's not always the case.
Drip emitters clog. Irrigation lines break. Sprinklers become misaligned. Watering schedules change. And as trees mature, their root systems expand far beyond the area they occupied when the irrigation system was originally installed.
An irrigation system that adequately supported a young tree 15 or 20 years ago may now reach only a small portion of that tree's root zone.
That's why mature trees often benefit from supplemental deep watering in addition to normal landscape irrigation.
Think Slow and Deep
For mature trees, supplemental watering shouldn't mean simply running the sprinklers longer.
The goal is to deliver water slowly and deeply throughout the appropriate root zone, allowing moisture to penetrate into the soil rather than running off the surface.
Slow, deep irrigation can help:
- Reduce drought stress
- Support root health
- Improve canopy vigor
- Increase resilience during periods of heat
- Provide moisture beyond shallow landscape irrigation
The appropriate amount and location of water will vary depending on tree species, size, soil conditions, exposure, and the surrounding landscape.
Mulch Makes That Water Go Further
Watering and mulching work hand in hand.
After providing supplemental water, a quality organic mulch layer can help retain that moisture and reduce how quickly it is lost to evaporation.
Mulch can also:
- Moderate soil temperatures
- Reduce evaporation
- Protect surface roots
- Reduce weed competition
- Improve soil conditions over time
- Help reduce compaction and surface crusting
In Santa Barbara's long, dry season, mulch can significantly improve the efficiency of the water you're already applying.
Mulch should be spread over the root zone where practical while being kept away from direct contact with the trunk and root crown.
Which Trees May Benefit From Supplemental Water?
Many of Santa Barbara's mature landscape trees can benefit from supplemental watering during prolonged dry periods.
Some of the trees we commonly consider include:
- Jacaranda
- California Sycamore
- Eucalyptus
- Olive
- Chinese Elm
- Gold Medallion
- Liquidambar
- Tipuana tipu
- Magnolia
Each species has different water requirements, so supplemental irrigation should still be appropriate for the individual tree and site.
What About Coast Live Oaks?
Native Coast Live Oaks require a different approach.
Established oaks are adapted to Santa Barbara's dry summers, and excessive irrigation—particularly close to the trunk and root crown—can create conditions favorable to root and crown diseases.
Supplemental watering for mature native oaks should therefore be carefully considered based on the tree, its irrigation history, surrounding landscape, and site conditions.
One watering strategy does not fit every tree.
Beaver Arborist Deep Root Watering
If you have large established trees and aren't sure how to provide adequate supplemental water, Beaver Arborist offers deep root watering as part of our tree health services.
Our approach allows us to provide supplemental water where mature trees can benefit from it rather than relying solely on existing lawn, drip, or landscape irrigation.
We can also evaluate the tree and surrounding landscape for signs of drought stress, irrigation deficiencies, and opportunities to improve moisture retention with proper mulching.
Don't Wait Until the Tree Looks Severely Stressed
One of the challenges with mature trees is that drought stress can develop gradually.
By the time significant canopy thinning, branch dieback, or premature leaf loss becomes obvious, the tree may have already been under stress for an extended period.
With no meaningful rain for months and continued warm weather, now is an excellent time to pay attention to your mature trees.
Look at the canopy. Check your irrigation coverage. Consider supplemental deep watering. And protect that moisture with mulch.
Final Thoughts
Our trees have made it through another long Santa Barbara dry season—but we're not at the finish line yet.
Until our first meaningful rains arrive, many mature landscape trees can benefit from some additional help.
Slow, deep supplemental watering combined with proper mulching can help reduce drought stress and support tree health through the remainder of our dry season.
If you're concerned that your trees aren't receiving enough water, Beaver Arborist can evaluate their condition and recommend an appropriate watering strategy for your property.
Need Help Getting Water to Your Mature Trees?
Beaver Arborist provides professional deep root watering and mulching services throughout Santa Barbara, Montecito, Hope Ranch, Goleta, Summerland, and Carpinteria.
Schedule a free consultation to determine what your trees need.