Have you ever wondered why landscape professionals stress regular aeration and overseeding to lawns? If lawn is important to you, aerating and overseeding is a must for any landscape. Aerating and overseeding your lawn is a powerful combination to create a lush green lawn. The process of aeration allows oxygen, water and vital nutrients to penetrate the root system of grass. Aerating also reduces thatch build-up; while, preventing compaction to lawn areas, which are of particular concern in Oregon. Overseeding is beneficial because it thickens and strengthens your existing lawn. This aids in reducing risk of lawn disease as well as weed germination. Routine aerating and overseeding ensures a healthy lawn; while a neglected lawn will thin out over time and become patchy with many weeds inter-mixed. For all our DIY landscapers out there we have complied a step-by-step list of what you need to know. Read on to learn how to aerate and overseed your lawn in Portland, Oregon
Mow your lawn a little shorter than you normally would. Mow at a height of about 1.5", but take caution not to scalp your lawn by cutting below grass blades-meristematic tissue. Therefore, if you normally allow your lawn to grow tall, cutting to this height may cut into the tissue. Mowing beforehand is important because taller grass may shade out new seedlings.
Raking out dead or brown spots in your lawn, allows the seed to have contact with soil. If you skip this step the brown spots will not germinate the seed.EXPERT TIP: Rough up newly exposed soil a bit, just prior to overseeding. This allows better seed germination. This should be done after aeration.
You are now ready to aerate your lawn. Start at a corner of the lawn and walk in straight lines, making sure to overlap slightly (similar to mowing). Once finished aerating in one direction, cross over the lawn going the other direction-perpendicular to your starting point. Having the cross-directional aeration allows optimal light and oxygen to the roots, while also allowing maximum seed to soil contact.EXPERT TIP: Aerator's are large and awkward to use for your first time. We recommend reading equipment directions in full and also watching a few youtube videos.
Now that your lawn is prepped, you can apply the seed. If you have a large area of lawn you will want to use a walk-behind spreader. A hand-spreader works best in small lawn areas. Whether you are using a walk-behind spreader or a hand spreader you want to apply at a rate of 10-15 lbs per 1,000 square feet of turf. Similar to the the aeration pattern, apply seed in one direction and than the other avoids missing areas. If you raked out dead spots, now is the time to apply concentrated amounts of seed to those areas and finish by covering with a thin layer of mulch (1/8" to quarter 1/4" thick). After the seed is applied, use a leaf blower to blow the seed that fell in your planting bed. It would be a weeding nightmare if you skip this step.EXPERT TIP: Use the appropriate seed for your light conditions. For shaded areas use a fine fescue and perennial rye for full sun. If your lawn has a combination of these lighting conditions, mix the two seed varieties in your spreader. Fiber mulch and peat moss work the best for this use.
This is possibly the most important step to get right. Seed watering is like the Goldilocks and the 3-bears; you want it just right, not too dry and not too saturated. The perfect saturation point is like a sponge, wet but not sopping. At this point all you need to do is wait 2-3 weeks for seedlings to establish. Typically, another seeding is required for thin areas or areas that were bare.EXPERT TIP: Water 2-3 times per day (depending on environmental heat) for 5-10 minutes per watering. It is important not to have washout areas as this will cause bare spots. After seed is established you can up your watering time to once a day for 30 minutes.
For optimal seed germination, it's better to overseed in temperatures between 60° and 85° F. Outside of these temperatures grass seed are in a state of stress and will not put on new growth. Overseeding in the Portland, Oregon area does best between September - October and April - July. This can vary depending on fall and summer conditions. In other words, seed germination flourishes in temperate weather.