Are your trees too hot?

Watch for signs of drought, learn to water right

By Sophie Wilkins / The Bulletin

The dog days of summer are here. We still have plenty of time to spend enjoying the lush foliage in our yards, but with the weather report calling for higher temperatures, extra care needs to be given to our trees.

In a recent news release from the Oregon Department of Forestry, Kristin Ramstad, an urban forester, said, “Summer temperatures can be hard on trees, especially landscape trees in our urban areas.”

Are sprinklers enough?

Deciduous trees (those that lose their leaves in the winter) show signs of drought with browning or wilting leaves. Trees needing more water will have leaves that can look dull or limp and may curl at the edges. They can also look smaller than usual, drop prematurely and turn yellow or brown and remain on the tree. Conifers or evergreens, like ponderosas or Douglas firs, have needles that turn brown, yellow, red or even purple.

Trees need more water than lawns or flower gardens and often won’t get enough water from an automated sprinkler. “If trees aren’t well-watered, warm weather and prolonged drought eventually make trees more susceptible to insect and disease problems,” said Ramstad.

Shallow or little watering encourages shallow rooting, which may lead to future problems for the tree. Ramstad suggests saturating the soil of the tree’s drip line during the cooler part of the day. The drip line is a circle that could be drawn around the tree, following the outermost branches. To saturate the soil, use a regular garden hose or soaker hose and water slowly; also rotate the hose around different areas of the tree. Another way to get to deeper roots is to use a water probe or mulch. Probes work like needles and pump water deeper into the ground.

Sydney Powell, owner of Niche Gardens in Bend, suggests that one of the most important things is to “pick an appropriate tree for the conditions where it will be planted.” She says keeping sun and shade needs, soil type and access to irrigation in mind when first planting trees is just as essential. Powell advises that one long soak per week, up to 30 minutes per tree, can be more effective than running irrigation for a shorter time on a daily basis. “Soaking a tree encourages roots to grow deep rather than spread shallow,” Powell says.

Other helpful tips

Mulch helps in warmer weather by keeping the soil cooler and retaining more moisture. Mulch, made of bark, wood chips, leaves and evergreen needles, can also be applied within the drip line. Applying it 4 inches deep while keeping a 6-inch space around the tree trunk typically works best, according to the Oregon Department of Forestry.

The best way to water conifers is to use a large bucket or container with a small nail hole in the bottom. Fill it up and let it slowly empty under the tree. Ramstad suggests doing this two to three times per tree, moving the bucket to a new spot each time.

Avoid planting annual flowers or other plants under your trees. They compete with the tree’s roots for moisture and nutrients.

Keep your trees as healthy as possible, suggests the Oregon Department of Forestry. They’ll keep you cool if you do the same for them.

— Reporter: 541-383-0651, swilkins@bendbulletin.com