Help your trees during drought

Hand-watering with a hose is still the most precise method for watering trees.

Although the size of mature trees demonstrates they’ve survived drought on their own many times before, experts suggest providing additional water if they’ve received no supplemental water or rainfall for more than four weeks.

With the most recent widespread rainfall in San Antonio now a month behind us, if you haven’t watered this month, it’s a good time to focus your efforts on your trees.

Trees, of course, are well accustomed to our weather patterns in South Central Texas and they typically receive most of their warm-season moisture, if any, in late spring and late summer. But if this month provides no beneficial rainfall, it’s helpful to know when to water and where to apply it.

You can fit supplemental tree watering within Stage 3 watering windows. Hand-watering with a hose is still the most precise method for watering trees. A water wand with a cut-off makes it easy: apply in a circular motion to allow water to soak in thoroughly. An inch of water can percolate six inches into the soil where many of a tree’s water-absorbing tree roots are located.

For trees, water absorption is handled by fine, hairlike feeder root. Although they may seem delicate, they play a vital role in absorbing nutrients and water for the entire tree. And in ideal circumstances, they may grow outward twice the width of the canopy height. They tend to occur in the highest density where water funnels every time it rains.

Once you understand this concept, you can use it to your advantage when applying water:

• Around the tree trunk’s root ball (at least 10 inches away from the trunk).
• Along the drip line. Think of an umbrella: the drip line is the circle around the perimeter where water sheds directly from the canopy to the ground.

During drought, when your goal is not really growing the tree larger but helping it survive, the area around the trunk well inside the drip line is a good area to focus on. In part because the density of roots may be higher a little closer to the trunk and because the tree’s shade keeps water from immediately evaporating, allowing it to be absorbed.

As usual, avoid wetting the trunk itself — start at least 10 inches away from the bark — and avoid obsessively oversaturating the soil under your trees. Remember, fine roots grow close to the surface not just for water but also for oxygen. Too much water can suffocate them!

Watering trees once-a-month is part of keeping them healthy, as they add real value to our property.

Avoid adding additional stress, especially during drought.

• Don’t prune trees excessively. Instead, use a certified arborist for major pruning (generally on a five-year cycle) and listen to their suggestions.
• Don’t install new sod or artificial turf during a drought. It can interrupt the function and recovery of a tree’s fine root system. Instead, add mulch (less than 2 inches) or compost (1/2 inch per year) to increase your soil’s moisture-holding capacity.
• Don’t use high-nitrogen fertilizer or weed-and-feed products around trees as they can cause rapid growth and quickly use up a tree’s energy stores.
• Don’t disturb the area under a tree’s canopy. Digging, trenching and compacting the ground around a tree will impact the fine feeder roots that provide water and nutrition.

Remember, maintaining a healthy shade canopy is never a “set it and forget it” process. As trees grow, they may tend to become overcrowded and begin to thin themselves out on their own.

Each winter (October through February) is a chance to have a licensed arborist conduct any pruning and, if necessary, diversify your existing tree selection by planting new ones so they can get established before hot weather arrives.

WaterSaver landscape beds are a great place to start new trees since they’re safe from the lawnmower and already mulched.

To learn more about watering and caring for trees, visit GardenStyleSA.com.