As promised, this week's email tip is all about the importance of a Core Aeration on most lawns. Much of what you are about to read was gleaned from RCW Nurseries website at www.rcwnurseries.com

During March, April and May homeowner thoughts turn to the quality of their lawns. A beautiful lawn is measured in terms of color, density and uniformity. Soil conditions, fertilization, and watering are the factors that affect lawn quality. Of these, the condition of your lawn's soil and your fertilization schedule have the greatest impact. Well, if you listen to GardenLine, or follow these tip sheets to any degree, you know how well the Lawn Fertilization Schedule works. Click Here

So, if you're following the schedule above and the lawn hasn't responded, then by all means it probably indicates really bad soil. It's entirely possible that the grass will be unable to take up the nutrients provided by spring fertilization due to poor soil conditions. Is the soil beneath your grass hard and lumpy? Does water run off after the grass has been irrigated? Does it always seem "thirsty", i.e. wilts by the next summer's day? Is it not as green as it should be? If so, then your lawn is a prime candidate for core aeration. I mention core aeration quite a bit on my program, but maybe we've never taken the time to explain it in detail.

What is Core Aeration?

Core aeration is a performed with a special machine that pulls out plugs of soil. This opens up the soil structure, allowing air, water and fertilizer nutrients to penetrate more deeply reaching the grass roots. Core aeration makes the soil more friable, "crumbly", a condition allowing roots to grow down rather than up. When roots are growing up this is thatch. Friable soil also helps earthworms, nature's core aerators, to better able tunnel through the lawn, moving more nutrients and water. Plus the casings they leave behind are excellent fertilizers.

Mid-March through April is a good time to do this as the soil is usually softer from our spring rains, making it easier to core aerate. Whether you perform the core aeration, or hire a company for the job, make sure the machine being used has the appropriate length tines and spacing. Soil scientists and turfgrass experts recommend tines are a minimum of 4-inches in length, with a spacing of 2- to 3-inches. If the tines on the machine are farther apart, it will need to go over the same area multiple times.

First, make sure to mark off sprinkler heads -- you don't want to run the machine over them. Not only will that damage them, it will also damage the machine's tines making it useless. Core aerate the lawn. The cores then can be either left to degrade naturally, or be broken up a day or two afterwards by simply mowing over them. Apply an organic lawn fertilizer at 2 - 3 times the recommended rate. The reason for choosing an organic fertilizer is that compacted soils are not only nutrient poor, they structurally weak, which is why they became compacted in the first place. Organic fertilizers contain materials that help build up soil structure. Because organic fertilizers have high amounts of insoluble nitrogen, this amount will last longer, allowing you to skip that midsummer feeding in July if you so choose. Once this has been done, water the lawn thoroughly to help move both the soil and fertilizer into the holes. The holes will eventually fill in, completely disappearing within month.

Why Spikes And Rollers Don't Work

Do not aerate your lawn by sticking sharp objects into the soil that do not remove a core. These only push soil aside to create a hole. In other words, they actually compact the soil even more. So wearing spikes on your shoes while mowing or walking on the grass is not a good technique.
Reducing "humps" in the lawn by rolling over them with a heavy roller only smashes the plants and compacts the soil. If you have a lumpy lawn, raise the surrounding low areas by spreading no more than one-half inch of topsoil mixed with compost, or humus. Do not use straight topsoil as it is too heavy.