A few weeks ago, I wrote about the gradual warming trend the Pacific Northwest has been experiencing over the past 15 to 20 years. The daytime high temperatures have routinely reached the 90-degree range, while nighttime low temperatures stayed in the 60s. These would be 10 degrees warmer than a typical normal range. Along with the warmer temperature pattern has been a more persistent dry spell from May until October. This harsh summer weather pattern has made growing the perfect lawn a real high-input, unsustainable gardening endeavor.
During our five-month dry season, high-end perennial ryegrass lawns take daily irrigation of about a quarter inch or almost two inches of water a week to maintain their thick, green turf. These lawns offer great beauty, a good fire safe barrier around a home, humidity to our often very dry air and good exercise to whoever is having to mow them.
There are, however, quite a few negatives that come along with these lawns when we work to keep them green and thick during our hot, dry summers. The primary concern is that our area as a whole is using a dramatic amount of water out of our rivers just to grow turf grass.
A few years ago, I noticed the Roseburg water system pulled about 5 million gallons of water a day out of the North Umpqua River during winter, and 10 million gallons a day during the summer. The difference, of course, was going on our yards. Not all of that water is just for lawns, but a large percentage is. Other negatives include the overuse of fertilizers and herbicides to keep the lawn looking good, hauling lawn clippings to the landfill and a lot of time mowing every week.
What I suggest that all homeowners work toward is a low-input, sustainable turf that doesn’t require large amounts of water, fertilizer and other chemicals. To start with, look into using a turf type tall fescue lawn. This turf grass retains its stand with half the water that a perennial ryegrass turf requires, and the new tall fescue turf selections retain good color during our cool winter months.
Tall fescue during the summer months will stay green with as little as half an inch of water a week. If you want to stop watering completely during summer, an established stand of tall fescue will survive and come back with the fall rains. To make sure your grass comes back quickly with the fall rains after turning brown, give your lawn area about a half inch of water a month at a minimum to keep the roots healthy.
Perennial ryegrass, Kentucky bluegrass and bentgrass will also go dormant in summer if not watered. However, they are not as drought hardy as tall fescue, and will require more overseeding in the fall when the rains return to restore areas that have died out. If your stand has dead spots and requires some maintenance, spread a little lime and run a plugging machine over the lawn to break up any compaction. Then, spread some seed. To minimize die-back with these turf types, I recommend applying about a half inch of water a week. The turf tops will get a little brown, but the roots will survive quite well.
The best low-input fertilizer plan is to apply a lawn fertilizer that has between 20 to 28% nitrogen, a very low phosphorus and potash content no greater than 2%. The bag will tell you how many square feet the content will cover. Just calculate approximately how large your turf area is and adjust your fertilizer spreader. The best time of year to apply your fertilizer is in April, when the soil is warming up, and the heaviest rain of winter has passed. If you allow your turf to dry out in the summer, a fall application of fertilizer is also recommended when the rains return.
We are currently accepting applications for our next Master Gardener training that begins January 2018. We will be taking applications now through Sept. 29 at the Extension office. Class size is limited, and a few openings are still available. If you are interested in learning more about gardening in western Oregon, come by our office to register.
For complete details, check the webpage at http://extension.oregonstate.edu/douglas/.