Trees may not wilt and die as quickly or obviously as a scorched lawn during bouts of severe drought. But the dry weather can take a significant toll on a yard's or boulevard's tallest plants.
"Healthier trees will be able to survive better," Jennifer Teegarden with the Minnesota DNR told Bring Me The News of a drought's impact.
Teegarden, a certified arborist, serves as cooperative forest management outreach specialist with the agency's Division of Forestry. She said people may see leaves changing colors or falling off right now. That's a sign of stress, as it's simply "too much energy for the tree to keep the leaf alive right now."
Newly planted trees and those less than 5 years old need the most attention, as they "are going to be the hardest hit," she said. The tree needs energy to establish new roots and continue to grow, which means they are more susceptible to drought-related damage, Teegarden explained. (The DNR has a page with more info here.)
This can seem easier said than done. Residents of cities and towns throughout the state are currently navigating varying levels of water usage restrictions, usually related to outdoor watering. Woodbury, for example, is now only allowing residents to water their lawns two days a week.
Fortunately, trees don't need to be watered every day. And in most cases, tree watering can easily continue despite any ongoing restrictions.
Minneapolis, the day after announcing its sprinkler restrictions, put out an alert reminding people that trees — both in a yard and on the boulevard area — need to be watered regularly during dry periods.
"Under the sprinkling restrictions, tree watering is allowed with a dripping hose, bucket or tree watering bag as needed," the city emphasized.
St. Paul Natural Resources released a few tips for property owners looking to keep their trees healthy, reminding people to just follow the alternating days watering guidelines in place. The department's suggestions for newly planted and immature trees were similar to many of Teegarden's, and included:
- Putting a ring of mulch a few inches thick around the tree to help retain moisture (but don't put it right up to the trunk).
- Putting a hose on a light trickle or steady drip, and setting it at four spots around the tree (imagine the points of a diamond) for 15 minutes at a time
- Doing the same with a 5-gallon bucket, filling it with water four to five times and pouring it at four points around the tree
The most efficient method, Teegarden said, is probably a 20-25 gallon watering bag placed on top of mulch, which will release moisture over time. (This is a good option for anyone who is going out of town and wants to make sure their tree gets enough moisture for the week ahead.)
For mature trees, the goal should be to water long enough for the top 6 inches of soil (where most of the tree's water-absorbing roots are located) to become moist, Teegarden said. Aim to water about as far from the trunk as the tree's canopy extends, she added.
A soaker hose is an efficient way to do this, and early mornings (when the temperature is lowest) are generally best.
So what about sprinklers? They're not ideal anyway, Teegarden said.
Not only will the heat cause the water to quickly evaporate, but the moisture can cause issues with conifer pine needs or deciduous leaves, including fungus or scorching.
This might seem like a new layer of rules atop existing restrictions. So, to put it another way:
"I generally tell people, if it hasn't rained an inch within the last week, it's time to water your tree," Teegarden said.