Edmonds Landscape and Construction Services Ltd.

Greenfacts
Volume 6.8 (1994)
Edmonds Environmental Services

There Is More to Mowing Than Just Cutting The Grass!

Mowing is what makes individual grass plants into turf and it is the most important and regular cultural practice you perform in maintaining your lawn. Mowing cuts off grass blades but does not injure the plants growing point at the surface of the soil (called the crown. Thus, grass plants are able to send out new blades and form a thick, dense mat of vegetation. If mowing ceased, grass plants would continue to grow and produce flowing stems and seeds.

Stress! Stress! Stress!

Did you know that improper mowing practices could be the primary reason for weed, insect, drought, and disease problems on your lawn? When mowing, a large portion of the plant biomass is suddenly removed and this continual removal week after week is very stressful to grass plants. No other lawn care practice has more effect on the overall health of your lawn than mowing. It is therefore very important to seasonally adjust your mowing practices to reduce the level of stress placed on your turf.

Start By Raising Your Mowing Height

Most lawns are mowed low for that "golf green" appearance. Each grass species, however, is physiologically and anatomically adapted to an optimal mowing height. Thus creeping bentgrass utilized heavily on golf courses is adapted to a low mowing height and can tolerate a cut as low at 7/64". The dominant species on most lawns, however, are Kentucky bluegrass and fine fescues which grow best at a mowing height between 3-4". Therefore, one of the best things you could do for the health of your lawn would be to go into your garage, and raise the height of your lawnmower blade as high as it will go.

Modify Your Watering Practices to Promote a Healthy Lawn

During unusually dry summers in Nova Scotia many lawns show signs of moisture stress. As a result, watering of lawns
has become a daily ritual for many homeowners. Watering must be done correctly, however, or more harm than good can result.

First of all, watering is not necessary to prevent your lawn from dying. The brown grass is not dead, it has simply become "dormant" as a protective survival measure. It is completely natural and the grass will begin growing again as soon as we receive significant rainfall.
If you want green grass throughout the dry summer months utilize the following watering strategies to ensure that you don�t put unnecessary stress on your lawn.

Only water when your lawn begins to show signs of drought stress. One signal is a colour change of grass from green to dull blue-green. Over watering is just as detrimental to turf as drought.
Water deep and infrequently. Shallow, frequent waterings promote shallow rooting and a lawn "hooked" on water. Most grass requires approximately an inch of water per week. The moisture should penetrate 4-6 inches to promote deep rooting.
Try to water early in the day. If you water in the evening, excess moisture can remain on the leaves into the night and this promotes turf fungal diseases.

Benefits! Benefits! Benefits!

There are many benefits from mowing high.

Deeper rooting of the grass plants
If you mow short, the plant has less leaf area available for photosynthesis (i.e. food production). Therefore, to maintain rapid regrowth of leaves following mowing, the plant will tap carbohydrate reserves in the roots. Thus, at a low mowing height, all the plant�s energy goes into growing leaves and root growth becomes a secondary priority. By mowing high and promoting deeper rooting, this helps the lawn recover more quickly from stresses such as heat and drought.
Leaf blades shade the soil
This reduces fluctuations in soil temperatures which stress grass roots and soil microorganisms. The shade also helps reduce moisture loss from soil via evaporation (see information on WATERING on page 1).
Reduction in weed population levels
Research indicates that for every inch a mowing height is raised, an approximate 10 fold decrease in weed numbers can be expected. The reason for this is that grass plants mowed higher are more vigorous and healthy and therefore are able to out complete most weeds. The shade resulting from longer leaf blades also reduces germination of new weed seeds.

Mowing high is particularly important during the summer. For the first few cuts in the spring and the last few cuts in the fall (especially the last mowing), you should lower your mowing height to 1-2.5" to increase turf density and prevent thatch accumulation.

Other Mowing Strategies

Mowing high is only one strategy in promoting a healthy lawn. Other important considerations include:

Make sure your blades are sharp. Dull blades tear grass and increase the incidence of fungal diseases.
Follow this simple rule, mow lightly and mow often. Avoid heavy cuttings as this weakens the turf plants.
Apply the "1/3 Rule". Try to cut no more than 1/3 of the leaf blade off at any one cutting. Removing more than 1/3 of the top growth exposes sensitive undergrowth tissues to intense sunlight, resulting in brown, sunburned turf. The plants could take weeks to recover from the stress and during this time the turf will be susceptible to insects and diseases.

In future issues of this newsletter, more details as to optimal mowing practices will be discussed. For the time being however, RAISE THOSE MOWING HEIGHTS!

Chinch Bug Alert!

If you notice round, yellow patches on your lawn, Chinch bugs may be the culprits! These bugs congregate in warm, sunny areas of turf and feed by sucking sap from grass plants causing them to die.

A simple procedure to test for Chinch is to insert one end of a coffee or juice can (with both ends cut out) about 2" into the soil. Fill the can with water and refill as necessary. Wait 10 minutes; if little 1/8" bright red bugs (called nymphs) with a white stripe across the middle of the body come to the surface, then you have a Chinch problem. Adults, 1/16" long, grayish black with white forewings will also be found on the fringe of damaged areas.

Large Chinch bug outbreaks are a symptom of a larger, underlying problem in the turf, thus outbreaks usually only occur on a lawn that is stressed. Therefore, your best defense is simply a healthy lawn! To control a current outbreak, try soaking infested areas with soapy water (1 oz. dish soap to 2 gallons water). Cover the area with a bedsheet to "capture" the bugs as they are driven from the ground by the soap solution. Vacuum or wash the sheet to remove the bugs.

Food For Thought

"Man did not weave the web of life, he is merely a strand in it. Whatever he does to the web, he does to himself� to harm the earth is to heap contempt upon the creator� contaminate your bed, and you will one night suffocate in your own waste"

Chief Seattle, 1854

Newsletter written by Brice Walsh, M.Sc.

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