Question: With all the warm weather we’ve recently been experiencing, I’ve noticed the grass in my lawn is really taking off. Could you give some advice on how to successfully manage my turf so it’s healthy and less weedy?
Answer: Thick, green lawns are such a desirable landscape feature for most homeowners. Not only are they beautiful, but they also provide a cooling effect around the home with humidity to offset the summer dry air, conserve soil, provide green space for recreation and an important safe fire barrier around the house — as well as great exercise for the one behind the lawnmower!
The most important cultural practices in maintaining a beautiful lawn are correct mowing, fertilization and proper irrigation. The key goal is a low-input, sustainable lawn that doesn’t require large amounts of water, fertilizer and other chemicals.
It’s a sure thing that even though your lawn was planted with a certain mix of desired grass seed, over time that lawn will change to a more naturalized grass mix as well as having other broadleaf plants (or weeds) that tolerate mowing. This is called the climax lawn.
Instead of obsessing over maintaining the perfect lawn to look like the local golf course, strive to be more tolerant of different grasses and work on creating a healthy, sustainable lawn.
It’s critical that you practice proper mowing. Most grasses should be mown at around 3 inches in height, the exception being bent grass, which should be mown at 1 inch height. Instead of bagging the clippings, which contain high amounts of nitrogen, consider using a mulching lawnmower which clips the grass into small lengths, returning them to the turf where they decompose and release the needed nitrogen, thus requiring less fertilizer.
Keeping the level of your lawn high encourages deeper roots and naturally prevents weeds from growing by crowding them out.
Keep your mower blades sharp so they don’t tear the grass blades. When the grass is growing rapidly, such as in the spring, mow at least once a week, and not when wet, to encourage the grass to thicken up.
Should the lawn have some bare spots, April is a great time to address those. Thatch develops over time and is made up of a thick layer of living or dead grass stems and roots which forms a barrier between the soil and the green blades, causing drought stress.
If the thatch is particularly thick, consider renting a plugging machine that removes spaced cores of thatch and aerates the lawn, then apply some lime and overseed the area.
Small bare spots can be roughed up with a rake and then seeded. Use a turf type tall fescue seed which tends to retain its stand with half the water that perennial ryegrass turf requires. Tall fescue also retains good color during the cool months of the year, and if you choose to let your turf go brown in the summer, it will survive and come back readily with the fall rains.
When applying a lawn fertilizer, use a mix that has between 20-28% nitrogen and very low amounts of phosphorus and potash — no more than 2%. Too much phosphorus has become an environmental problem as it ends up in our waterways, stimulating algae growth which depletes the water of oxygen, resulting in suffocation of living organisms in the water system such as fish populations.
The best time of year to fertilize is now, in April. Then monitor your lawn for signs of nutrient deficiency and only apply fertilizer as needed. Apply a fall application after the rains return if you’ve allowed your lawn to dry out in the summer.
How often and how long to irrigate your lawn depends on your soil type, the season and how green you wish to keep it. A lawn growing from our common clay soil would do best with a shorter, more frequent watering schedule to keep the root zone moist without producing runoff. If your soil has been amended before planting, water less often, but for longer periods which allows for deep root penetration.
Best time to water is in the morning. Test the soil moisture by simply inserting a probe, such as a screwdriver. If the tool penetrates easily, reduce your watering rates or frequency; if it takes some effort to push it in, then increase your rates.
Another option is, again, to let your lawn go dry during the summer. As long as your lawn has been healthily maintained, it should come back green when fall rains begin again.
Lawn care is a huge subject, so for more information, you can visit the OSU catalogue website to download a free brochure: catalog.extension.oregonstate.edu/EC1521.