NEIGHBORHOOD GARDEN FOR MARCH 6, 2010

 

MYTH BUSTERS:LAWN CARE

BY GEORGE EDGAR

 

          There are a number of gardening myths about how to plant, how to take care of trees and shrubs, how plants grow, and lawn care. Today I want to deal with some of the myths about lawn care and see if they are fact or fiction.

GYPSUM WILL BREAK UP HARD CLAY SOIL!!! (FICTION) For years advertisers have told us to add gypsum to break up hard clay soil. Gypsum is a salt also know as calcium sulfate (calcium and sulphur). Both are micronutrients needed by plants, but the soils in Southeast and South Central Nebraska have sufficient amounts to grow grass and most plants. The addition of gypsum is used to amend sodic soils found mainly in arid regions of the Western United States . It is also somewhat beneficial to saline soils found in parts of Southwest Nebraska . Adding organic matter such as grass clippings, leaves, peat moss, or compost is the best way break up the hard clay soil most of us have.

MOW LAWN SHORT SO DON íT HAVE TO MOW AS OFTEN!!! (FICTION) In East and South Central Nebraska, mowing your lawn shorter than 2.5 to 3.5 inches only stresses the lawn, especially in the hot summer. Grass does not like to be mowed and always desires to get back to a length that is not stressful. To get there, it will grow faster if mowed too short. Mowing at a height of at least 2.5 to 3.5 inches shades the soil and the crown of the grass, keeping them cool, thus reducing stress and the amount of moisture loss from evaporation. So donít mow short. In the spring I set my mower as high as it will go and leave it there all summer.

GRASS CLIPPINGS LEFT ON THE LAWN WILL CAUSE THATCH!!! (FICTION)  This is a myth that is passed on quite often as the reason to bag clippings. The truth is, grass blades are 90% water and full of nitrogen. If you leave your grass clippings on the lawn (even if you donít have a mulching mower), they will supply the equivalent of one application of nitrogen per year. Thatch is due to mowing your lawn too short and over fertilization. Thatch is composed primarily of grass crowns and leaf sheaves. Core aerating at least once per year will open up your lawn and allow those stems to deteriorate naturally and add organic matter to your soil, thus breaking up all that hard clay stuff. Also, if you do this you will not have to power rake which is very hard on the grass.

Grass clippings left on the lawn are good organic material and will help break up clay soil. I do not understand why people bag grass clippings and then pay someone to take them to the landfill. What a waste!!!!! The only time you need to bag grass clippings is when you mow off more than 1/3rd of the blade.

          I GET WEEDS IN MY YARD BECAUSE SEEDS BLOW IN!!!

This is partly true. Many weeds do come from seeds that have are blown in, or are brought in by birds, or other animals. However, most of the seeds that germinate and then grow in your lawn come from weeds in your yard that go to seed and then the seeds drop onto the soil where they will germinate and take hold if you have an unhealthy lawn, or a thin lawn, or bare spots. Most weeds seeds will be choked out in a healthy lawn that is not mowed short.           What is a healthy lawn? One where the cultural practices do not stress the grass. For a bluegrass lawn or a turf type tall fescue lawn, the four major cultural practices that stresses lawns and thus promotes weed growth are:

          1.  Mowing too short. In addition to stressing the grass as I said earlier, University research has found that if you mow grass at only 1.5 inches high, the weed infestation rate in tall fescue is 45% and in Kentucky bluegrass is 55%. A lawn mowed at 2.5 inches has an infestation rate of 23% in tall fescue and 25% in Kentucky bluegrass. A lawn mowed at 3.5 to 4 inches has an infestation rate of only 2% in tall fescue and 7% in Kentucky bluegrass.

2.   Compaction of our hard clay soils. This is caused by traffic from kids, pets, and adults walking and playing on the lawn, and even by lawn mowers, especially heavy riding mowers. Also do not walk of on wet lawns or gardens. Your footprints really compact the soil. The lawn needs to be core aerated at least once a year either in the spring or fall to relieve compaction and break up the hard clay soil. It also allows for proper drainage. Grass has a hard time growing in hard compacted soil.

          3.   Improper watering practices. Correct watering means watering deeply, especially in the spring and fall. Put on 1.5 inches of water per week during the growing season, and apply at least 1/2 inch minimum when you water so that the water gets down to the deepest roots. Shallow watering creates shallow roots. And do not water after 2:00 pm in the afternoon so leaves will dry before evening. A drop of water on the grass blade or on a plant leaf overnight is needed for most disease organisms to grow. Water properly and avoid disease problems.

          4.   Over or under fertilization. Over fertilization really stresses the grass, especially if applied in the early spring. The most beneficial fertilizer is the application of a winter or late fall fertilizer after Halloween. If you  only fertilize once per year this is when to put it on. 

          The best times to seed a new lawn or re-seed a thin lawn are from April 15th to May 15th and from August 15th to September 15th.

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