QuestionQUESTION: I live outside Charleston, SC on land with 8 to 16 inches of real "dirt". Beneath the dirt is hard-packed clay. The water table is 12 to 18 inches beneath ground level. Basically, it's a drained swamp developed into a subdivision (much like most of the "lowcountry").
I have trees I'd really like to keep; "wet oak", sweet gum, and pine. The roots in much of the yard are growing at the surface, in some cases, above ground enough for the lawnmower to scrape the roots (and its set about 3" blade height).
How can I best cover the roots? The goal is cover/protect the roots, and cover the top with St. Augustine sod.
Thank you.
ANSWER: You can safely cover tree roots as long a sit is not more than about 2 inches of fill. More than this will damage the roots. I would use sand since you are going to sod the area. And since you are going to sod. Sand is better than clay soil since it will not compact as hard and damage the roots. I would just add sand to even with or just above the roots and lay the sod on top. Since the water table is not far beneath the surface over the years the roots may again become exposed from the growth. When this happens just add more sand.
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QUESTION: Could you explain what you mean by "damage the root", please. Forgive the ignorance. But, if I have a better definition of what damages the root and how it effects the root system &/or tree, it would help keep mistakes from messing up these guys.
Are there safe & effective ways to re-direct the root's growth path? Like away from the house foundation, sidewalks, like that?
Would landscape cloth before . . . or after the sand help or hurt?
With some of these roots being about the size of my forearm, would you recommend blending the sand with rock about the size of peas? A little bigger than sand, but very few sharp edges.
Your previous answer seems to suggest drainage is important.
Thanks, again!
Answer" Damaging the roots" referred to the added soil. When you add soil over roots it tends to compact the air spaces and the roots can not "breath". They need the air to grow. Clay soil has less air pockets than sand that is why I recommend sand and only a few inches deep. Also added soil will be heavy and compress the soil that is there. Sand tends to be less a problem than clay soils. Just do not add too much over the roots.
No the landscape cloth would not be advisable or needed. The cloth is to keep down weeds and provide some moisture holding help. You do not need any more moisture and the weeds will not be a problem here. Use only sand mixing it with rock will add weight and compress the soil that is there now and cause the air pockets to decrease.
Roots tend to grow toward water and unless the tree is within 5 feet of the foundation it should not be a problem to the foundation. No need to try to direct the roots growth away. Roots when they hit a foundation will either grow down under the slab or turn along the foundation. Down would mean possibly hitting the water table so I would think they would turn along the cement. If the tree is close to the house say 5 feet the large roots may push against the foundation but the main concern of trees near houses is the rubbing of the branches on the house. From what you have described the roots will not be a problem to the foundation.
Drainage is important in that the roots can not live in saturated soil for long and that is why they are coming to the surface to grow above the water table. Not really anything that can be done about this.
This can get pretty complicated and long so here is a web link that discusses roots airspace and water that will explain this process. http://www.grounds-mag.com/mag/grounds_maintenance_dont_stumble_surface/
