Maybe you’re a Freedom Lawn fan – anything is possible as long as it’s green and doesn’t break the lawnmower. It’s good. Perhaps you have higher demands on your greens, but you aren’t ready to invest the time and money it takes to turn your lawn into a velvety Kentucky bluegrass rug, nor are you willing to pay the environmental costs to cause associated with such a monoculture. Even so, you want something more than a field of clipped weeds. Fortunately, you can have this good-quality lawn without undue effort and material expense. Usually only a few timely procedures are required, and the time has come for most.
This is the time to think about fertilizer. The popular setting is that spring is the feeding time of the lawn. Then the garden centers put the sacks of lawn food on the shelves and the advertisements appear for four-stage programs. The fact is, however, that early autumn fertilization for grass is most important and one feeding per year at this time is enough for a sufficiently good lawn.
Of course, every lawn fertilization should start with a soil test. Otherwise, it’s like salting a dish before trying it – you can add too little, which is unfortunate, or too much, which is worse. An inexpensive soil test from your state agricultural university laboratory will show you exactly how much nutrients your soil needs. With this information, you can apply just the right amount of fertilizer of the right formula – enough to meet your lawn’s needs without injecting excess nutrients that wash away and contribute to water pollution.
One point to keep in mind when shopping for your annual lawn fertilization is that your lawn most likely does not need phosphate or potassium, the second and third numbers in the fertilizer formula. In fact, Vermont, New York, Connecticut, and a number of other states legally limit the amount of phosphates you can apply to your lawn without a recent soil test indicating it is needed.
When purchasing lawn fertilizers, it’s also important to consider what types of nitrates (the first number in the fertilizer formula) the product contains. In general, you want a high level of “slow release” nitrogen, which can be listed as water-insoluble nitrogen (WIN). These nitrates are released into the soil more slowly, at a rate the grass can make better use of, so they are less likely to wash away with surface runoff and pollute local streams, ponds, or lakes. A good rule of thumb is to use a fertilizer that contains at least 30 percent slow-release nitrogen on non-sandy soils and 60 percent slow-release nitrogen on sandy soils.
Organic fertilizers tend to naturally release their nutrients more slowly as they depend on soil microorganisms to break them down into a form useful for plants. When using organics, make sure that what you are applying doesn’t have too much phosphate as this can be a problem with animal manures and even compost.
Another practice that can significantly benefit your lawn is ventilation in late summer / early fall. Over time, traffic across the lawn tends to compact the soils, especially clay soils, making them less hospitable to root growth and less able to absorb moisture. The best way to do this is by renting a core aerator, a machine that pulls soil plugs out of the ground, leaving a pattern of small holes and a scattering of soil cores on the surface. The plugs can be allowed to dry and then broken open and redistributed with a rake. Core ventilation is best done when the weather has cooled and the soil is only slightly damp. When the soil is wet, the compaction problems are only exacerbated.
One final measure to consider is liming. This should only be done if necessary, if a soil test determines that your soil is too acidic. However, I have found that in acidic soil, applying lime in the amount recommended in the soil test results can have a profoundly positive effect on the growth of turf grasses and favor them at the expense of weeds. In fact, healthy, vigorously growing grass is the best weed repellant and everything you really need to make your lawn good enough.
Be-a-Better-Gardener is a non-profit service run by the Berkshire Botanical Garden in Stockbridge. Its mission to impart knowledge about gardening and the environment through 25 show gardens and a variety of classes informs and inspires thousands of students and visitors on horticultural topics every year. Thomas Christopher is co-author of Garden Revolution (Timber Press, 2016) and a volunteer at the Berkshire Botanical Garden. berkshirebotanical.org.