Publications (Paul's Blog)

November 19, 2009

LAWN GRASS VERSUS SHADE TREES

Filed under: Uncategorized — Paul Dowlearn @ 6:52 pm

The age old battle continues. Homeowners are dedicated to their lawns. More time, money, and precious water is spent on the American lawn than any other landscaping feature. On the other hand, most people enjoy the benefits of shade, especially here in Texas where summer is the long season. Outdoor temperatures are normally uncomfortable to say the least and can get downright dangerous. Problem is, lawn grasses are sun lovers and large trees deny the shorter grasses their share of sunlight. Most folks want their lawn to be lush and beautiful right up to the trunk of that tree. However, Nature has a different plan, and so the stage is set for the homeowner to attempt to have their way with Nature.las1
As ridiculous as it is, the way this has been done is trim the trees to allow more sunlight, plant more grass, trim trees again a few years later, plant more grass, trim trees, plant grass, trim trees, and so it goes. When you look at this logically, trimming trees reduces shade, the very thing we planted them for. Planting more grass means continued mowing, watering, and fertilizing chores. The combination of trimming trees and replanting grass results in higher maintenance. Yet nearly all homeowners say they would like to spend less time and money in their landscape. If so, then we need to consider alternatives that will result in lower maintenance.
The evolution of an average landscape goes something like this……….When a housing addition is first built the newly planted trees are small. The environment is somewhat akin to our Texas prairie. Grasses thrive in these conditions (full sun). Your new homeowner finds the cheapest way to cover the bare soil is to sow Bermuda grass seed. So most of us will start out with a bermuda grass lawn. We are anxious for our trees to grow at this point. We will fret over them and give them extra water, mulch, and perhaps some fertilizer to speed growth.
After twenty years or so our trees begin to mature and the neighborhood environment begins to change. Some folks who have planted faster growing trees or have planted lots of trees will have already begun to fight the battle with shade. Bermuda is the least tolerant of shade in comparison to the other grasses we have to choose from. Most folks will switch to St. Augustine as a more shade tolerant choice even though purchasing sod is expensive and labor intensive. Your average homeowner is still able to accomplish the dream of lush lawn and shade trees at this point. All is well.
Another decade or two later and the neighborhood is full of large trees. The homeowners have finally received the comfort and other benefits of shade. The outdoor environment is now much more tolerable. We are no longer living in a semi-arid prairie. Now we have a cooler, moisture retaining, woodland environment. However, instead of being satisfied with this obvious improvement, the hapless homeowner begins tree pruning in earnest, perhaps even totally removing a few, all for the sake of grass.
On any given day, you can visit any older neighborhood and find your local tree guys happily employed. Meanwhile just down the street, another company is installing sod. So goes the battle between shade and grass. Is there a better alternative or a happy medium to this endless cycle? Which choice gives us the greater value or benefit?
Although many people probably don’t think about it, grass does absorb energy from the sun and does have a cooling effect. Grass also gives us oxygen in exchange for carbon dioxide as all plants do. Our Texas Water Resource Board lists our best choices in lawn grass in terms of water usage as follows. Buffalo grass is most drought tolerant requiring quite a bit less water and mowing. Zoysia grasses are listed second. Bermuda, the most popular variety, actually takes third place and St. Augustine comes in fourth. Fescue, which is often used as a last ditch effort to grow grass in shade did not even make the list.
If you are interested in low maintenance then you will easily surmise that more of us should be considering buffalo and Zoysia. In reality, over 90% of the lawns in Texas will consist of bermuda (number 3) or St Augustine (number 4) or a combination of both. Both are high maintenance water loving grasses.
When it comes to shade, zoysia varieties are the better choice. Zoysia grass will tolerate as much shade as St. Augustine with less water and mowing. It is perfectly cold hardy and resistant to insects and disease. A new variety called Palisades zoysia has done very well as an alternative here in North Texas. It is a wider bladed variety that can be cut with a rotary mower. It blends well with bermuda and is darker green than St. Augustine. It is not the miracle grass of our dreams and will have to be replaced after the trees have been thinned just like any other shade tolerant grass. However, it is a much better choice for most Texas lawns.
Sooner or later, homeowners living in older neighborhoods will be faced with this choice. Less shade or less lawn grass? The only real long term solution is to switch from sun loving grasses to shade loving las2 woodland plants or to use hardscaping such as wood decks, sitting areas, and pathways instead of living groundcovers. Our urban forestry professionals will tell you the shade tree is much more valuable than grass. These guys have a point system to evaluate and put a dollar value on trees. As far as I know, there is no real estate value placed on lawn grass other than aesthetics.
My personal choice for shade would consist of blooming perennials and woody shrubs combined with pathways and sitting areas. To me, this is much more pleasing than a simple groundcover. Nature is about diversity and a shade garden can certainly be diverse. Color can be had during Spring, Summer, and Fall plus we can choose a few evergreens for Winter. On the other hand, if all you want is a green groundcover to fill in where the grass won’t grow, there are plenty of choices.
Most people prefer a groundcover that is not very tall. Our old standby traditional choices are Asian jasmine, English ivy, trailing periwinkle, ajuga, and violets. Problem is that with the exceptions of ajuga and violets, these plants get at least two feet tall plus the Asian jasmine and English ivy can climb. Not really what today’s low maintenance landscape calls for.
Some lesser known but shorter groundcovers would include horse herb (calyptocarpus vialis), ground ivy (glechoma hedera), sedum (several species), dichondra (d. carolinensis), blue plumbago (ceratostigma plumbagnoides) and golden groundsel (senecio obovata). All of these grow less than a foot tall (some mere inches) and are quite mowable if need be. They will thrive in deep shade but will be dominated by your lawn grass where sunlight is available. All you need do is get some started around the tree trunks and allow it to spread until it hits the lawn. Keep the whole thing neat with the lawn mower if you so desire. As the tree grows (and it will) your shade loving plants will grow out with the shade line.
When I suggest this to folks as an alternative that really makes long term sense I am usually met with several questions. Number one is “Is this invasive?” The answer is yes, BUT not near as invasive as the bermuda grass you already have. Invasiveness is actually a desirable trait in a ground cover. You really do want it to get out there and cover that bare patch…………Right?? The second question………Will it take over my grass?? Again, few plants are as aggressive as bermuda grass. Any of these groundcovers will mingle with your grass at the point of contact unless you provide some sort of border to separate the two. Your grass will dominate in the sun, the groundcover will dominate in the shade, and the two will mingle in the partial shade. Grass after all is simply a groundcover
So the answer to that age old battle between lawn grass and trees is that the tree gives us homeowners the greater value. In addition, the tree will continue to grow larger unless it is cut completely down. Cutting trees down for the sake of grass does not make sense fiscally plus it is environmentally irresponsible. Climbing trees is dangerous. That job is best left to professionals who are generally not going to risk injury at a cheap price. The best thing is to switch to plants that will grow well in shade. Think pathways, ponds, sitting areas, and etc. Be innovative. Or be prepared to spend lots of time and money attempting to force grass where it does not belong.

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