Portland's big trees need water more than you may realize
The Pacific Northwest is better known for people who hug trees than for people who water them. But if you really love your coniferous companions, get out the hose.
A recent press release from a tree health specialist with the Oregon State University Extension Service offered a grim diagnosis for the ubiquitous Douglas firs in Southwest Portland: Because of drought conditions, they are dying. And noble firs, grand firs, western red cedars and Port Orford cedars aren't doing so well, either.
Should we be worried?
The SW Connection checked in with Southwest Portland certified arborist Peter Torres, owner of Multnomah Tree Experts, to find out.
Or is the question, "How worried should we be?"
"Basically, pretty worried," Torres said. I anticipate that we will lose 15% of native conifers within the metro area within the next 10 years if current trends continue."
Multnomah Tree Experts does 90% of it work in Southwest Portland and 30% of that work is removing tress that have died for one reason or another.
"The Douglas firs are dying quite a lot," Torres said. "Grand firs have been in trouble for quite a while but only recently have I seen whole trees die without evidence of a mass beetle attack. Cedar trees dying is the most surprising thing to me. I always found them to be more drought-resistant. I thought cedars and firs were bullet proof and we would never have any trouble with them because just imagine if they start to die en masse. It would change the city's landscape and bankrupt a lot of people.
"Well, if you have a 120-foot Douglas fir in a small backyard and it dies you could spend $12,000 taking it out. Or even $24,000 if you need a crane or aerial lift," Torres said.
In the press release from OSU Ag Extension Services, it's recommended that between August and September you water your trees up to three hours per week through September.
"Sure," Torres said. "In fact, that's one of the things people don't worry about. We're always told to water a tree for the first two years after you plant it and it will take care of itself after that. But it doesn't always do so. With conditions getting drier and hotter, more trees are going to need irrigation."
To take full advantage of fall and winter rains when they arrive and give your water bill a break, Torres recommends "mulching" your thirsty trees.
Basically you buy some bags of mulch for $5 each and spread the mulch under your tree. Not right under it near the trunk, but out around the outer edge of branches. (That's why, when you take temporary shelter from rain under a tree, you don't stand near the outer branches.)
Torres explains, "It really worries me to see conifers that aren't mulched. Bare dirt or grass don't hold the moisture. So the farther out you can go with the mulch, the better.
"Think about the mechanics of the tree when the rain hits. It flows down the outside of the branches first, then it drips down at what is called the 'drip edge.' That's the end of the branch structure where most of the water is going into the soil," said Torres, who's been working around trees since 1978.
It seems logical but people aren't always anxious to be spreading circles of water-absorbing mulch under the big trees in their backyards.
"Sounds simple," Torres said, "but when someone's got a lawn they've just spent thousands of dollars on, they're not just going to bury it with mulch."
The solution to the problem of drought-weakened trees dying is obviously lots of rain. But even if that happens, the tall trees we take for granted will still be stressed and could use an occasional watering. And mulching.
"One thing I'm not looking forward to is taking down a lot of dead conifers. Taking down dead trees is the least rewarding thing we do," Torres said.
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