The Garden Guru: Embrace the darker side of the landscape
04/04/2014 12:00 AM
04/03/2014 12:10 PM
We gardeners are certainly a curious lot, and this is the time of year when our minds start cranking out questions. Without a doubt, the one that I’m asked most frequently: “What kind of grass can I grow in the shade?”
It’s something that crosses almost every homeowner’s mind as shade trees grow larger and shade patterns become broader and heavier.
We Texans love shade, but it’s not good news for turfgrass. St. Augustine and fescue, our two most shade-tolerant grasses, both require four to six hours of direct sun in the summer if they’re going to thrive or even survive.
We’ve spoken here before about how you might be able to salvage such an area for turf. I won’t go into great detail again, but it involves determining for sure that the heavier the shade, the worse the grass does.
That usually means that you start at the trunk (heaviest shade) and work your way out to the drip line. If it’s a shade issue, the grass will get progressively more vigorous as you move away from the trunk.
If you decide that shade is indeed involved, and if you’ve already tried St. Augustine (fescue requires too much water here), perhaps you can remove one or two low-hanging branches so that more sunlight can reach the grass early or late in the day.
Those are the steps if you’re insistent about having turfgrass beneath trees. Let’s assume that you’ve tried those without much success. Rather than wasting more time, money and effort hoping that some miracle grass will solve all your problems, it’s time to move on.
Here are the next two most common questions I hear, along with my comments in reply. First: “Can I add fresh soil to cover the bald spot beneath my shade trees? I’m seeing tree roots, and I think the soil has eroded.” My answer is almost always to discourage bringing in any new soil beneath trees.
Oh, if you can see actual erosion, where that area is significantly lower than the surrounding area, I guess there might be a time when that could be needed. However, those are very rare, so think before you react.
What is almost always the case is that the tree roots have grown larger and worked their way out of the ground. Almost all large trees have 90 percent of their roots in the top foot of soil. As the trees’ trunks grow larger, so do their roots, and those that are closest to the soil surface actually grow up and out of the ground. Covering them accomplishes nothing. They’ll merely continue getting larger, until once again they’re up above grade.
Your only good solution: Leave them in place. They’re part of the character of the tree. Don’t risk harm to the tree by bringing in soil.
One of the best ways of concealing those roots and the bare soil as well is to establish a new planting bed to grow where the grass is thinning and dying. And that’s precisely where the second most-asked question pops up: “Is it OK to make a circular bed — a tree ring — around my tree, so I can grow flowers around its trunk?”
I hate to sound like a negative kind of guy, but that’s not usually a good plan either. Almost all flowers require as much sunlight as grass or more, so they’re likely to face the same fate. And those that do survive probably won’t bloom very well. Even the shade-loving types may have trouble competing with tree roots for moisture and nutrients.
But, at least for me, the really big reason I don’t use tree rings is purely personal. I’ve never thought that trees’ trunks were their most beautiful feature, and I’m not fond of drawing undue attention there by planting color right up against them.
A plan that works
My own solution is to develop elongated and irregularly curved beds to enclose the trunks and shaded areas, even extending a few feet farther to allow for future growth of the trees’ canopies. My goal will be to establish a shade-tolerant ground cover there — one that can act as a neutral green transition from the tree to the turf.
I use generous amounts of regular mondograss beneath our pecans, but I also have large beds of liriope, wood ferns, aspidistra (must be covered in cold winter weather) and even purple wintercreeper and Asian jasmine.
I like color in our landscape as well, so I’ll find a few pieces of garden art that are tasteful and that bring compatible colors to their surroundings.
I also have large concrete stepping stones arranged in groupings of three or five toward the outer edges of the ground-cover plantings. Those stones allow me to place large containers filled with caladiums, begonias, coleus and other shade color atop the stepping stones in the growing season, then leave them as neutral elements during the winter.
Texture is also your friend when it comes to bringing interest to your shade garden. Use plants with a wide variety of landscaping textures. Aspidistra contrasts with wood ferns for shorter plantings.
Oakleaf hydrangeas look really nice alongside most hollies if you want something taller. Or mondograss alone has a nice, soft texture about it if all you want is low ground cover.
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