If your lawn has seen better days, OSU Extension Service Urban Horticulturist, Weston Miller, can help! He stopped by with helpful tips on when and how to renovate your lawn.
Renovate your lawn in late summer
Are you tired of your lawn looking ragged? To maintain a lawn that will impress your neighbors and friends, it needs to be renovated every five years or so to keep the grass healthy and competitive against the ever-present barrage of weeds that will encroach on your turf. Learn practical tips for lawn renovation and lawn care to keep your yard looking great.
Get clear on your grass goals to know what your lawn will need
Maintaining a healthy lawn requires time and energy. The smaller the lawn, the easier it will be to maintain. Think about your lifestyle and how much lawn you really need for recreation and aesthetics. Consider replacing some or all of your lawn with landscape beds or hardscape, which require less care than lawn. Also, get clear on how you want to maintain your lawn. You can let a lawn go brown in summer and it will green up with fall rains, but it will be less competitive against the weeds and will require renovation more frequently. A four-season or manicured lawn will take more time and resources to maintain in terms of mowing, watering, and fertilizing, but will not need to be renovated as frequently.
Renovate lawn mid-August – mid-September for best results
During the late summer, soil temperatures are warm and grass seed will germinate quickly, which makes this the ideal time of the year to renovate your lawn. The best defense against weeds is to grow a vigorous stand of turf! Don't seed after October 15, as germination will be poor and your stand of grass will not be able to out-compete the weeds come spring.
Remove unwanted weeds first
If dandelions or other broadleaf plants exist on the lawn area that you want to renovate, start by removing these weeds. If you plan to do this by hand, pre-water the area to loosen up the soil to make it easier to pull the weeds by hand. A hori-hori gardening knife can make this chore relatively easy. If the weeds are very abundant, consider using a broad-spectrum herbicide to kill all of the grass and weeds several weeks in advance of soil preparation.
Create the right soil conditions
Turf grass needs the right soil conditions in order to prosper. Consider getting a soil test for pH and/or add lime (calcium carbonate) to help neutralize acidic soil conditions. Grass in lawns grows best when the pH is between 6.5 and 7. Native soils of the Willamette Valley are typically more acidic and require lime to grow healthy turf and keep the moss at bay.
Expose the soil surface
Rent a power dethatcher or use a hand-dethatching rake to expose soil for seeding and to remove moss and weeds. Go over the soil as many times as needed to expose the soil to ensure good seed-soil contact. If soil is severely compacted, rent a core aerifier machine and use it after dethatching. Go over the lawn several times. Then use the dethatching machine one more time to break up the soil plugs left on the soil surface by the aerifier.
Choose the right mixture of grasses for West of the Cascades
Seed for lawns typically comes in mixes with different grass species based on the intended use of the lawn. Most mixes for the Willamette Valley will have about 70-80% perennial rye and 20-30% fescues. If your lawn will receive heavy traffic from kids or dogs, look for mixes that are 70-80% fescues to withstand heavy use. For shadier areas, look for seed mixes designed to tolerate shade by reading the product label carefully.
Ecolawns are becoming more popular and consist of grass seed along with seed of low-growing, drought-tolerant, flowering plants such as clovers, yarrow, and English daisy. The added diversity of plants reduces water and maintenance needs and looks beautiful. Look for ecolawn seed mixes at the nursery.
Apply seed liberally
Follow the instructions on the seed package in terms of application rate. Buy a seed spreader to ensure a good spread of seed across the renovated area. Divide the seed needed for the whole area in half and disperse the seed moving in two directions to ensure adequate coverage. Remember that grass seed is relatively inexpensive and you want to error on the side of over application to ensure a good stand of turf grass that will compete against the weeds!
Apply fertilizer just before or after seeding; reapply fertilizer four to six weeks after seeding too. Purchase fertilizers with a high percentage of nitrogen that are intended for lawns. These first two applications of fertilizer are the most important for your lawn to get off to a good start by providing food for proper establishment before winter.
Water frequently until germination occurs and thereafter
Consistently moist soil is key for good seed germination. If possible, water four times per day until soil starts to glisten until the seeds germinate. This step should be easy if you have a built-in watering system with a timer. If not, purchase a programmable timer to put on your hose bib and use an oscillating sprinkler such that you can water the whole area without having to move it around. Keep the soil moist, but not waterlogged. Once the seed germinates, gradually reduce watering to two to four times per week. Mow your renovated lawn after about four weeks to two inches high.
Contact OSU trained volunteers for questions about lawn renovation and other gardening questions: http://www.metromastergardeners.org/index.php