Mesquite in Therapy
This tree needs help.
For comparison, here’s a picture of a nearby tree:
This is what a healthy honey mesquite should look like in summer. You can even see that this tree is having a bit of a second round of flowers just now, due to recent rainfall.
Back to that first tree:
This tree is drought-stressed. Note that the ground slopes away toward the left rear of the picture. The tree is planted in the decorative rocks that go around the back yard, and has a small ring at its base that is supposed to be rainwater catchment or something. First off, no tree planted in the desert by humans (much less landscapers!) should be planted on a mound, ever. Clearly, any water falling anywhere near the tree will immediately run off to the left. And as a catchment basin, that little ring may have been sufficient 15 years ago when the tree was planted, but it definitely won’t do much good now. At this point, it has filled in and is higher than the ground around it, making it even less useful to the tree.
So I decided to dig a moat.
After considering everything I could think of regarding this project, from ground slope, to the current size of the tree and the likely depth of the roots, to the proximity of moby-sized rocks to use as retaining barriers, to how to handle overflow run-off, and — well, everything I could think of — I began work.
First, I removed and set aside the decorative rock ground cover so I can use it elsewhere in the yard. Then I marked out the size of the basin and where the overflow would go, and I started digging.
I started digging on the higher edge, since any pool I can get to form there will be most helpful to the tree in the short term, plus soften up the dirt for more digging. This will be a much bigger excavation than the garden bed last year, but it will only be a foot or so deep at the deepest end (i.e. the high side). I decided to keep the little ring around the tree, because it seemed like a bad idea to dig right next to the tree, possibly damaging roots. I’m hoping that roots further out will turn downward as they find themselves being scraped from above.
The digging is going a little faster than last year:
Along the bottom edge of the moat (that’s near the top of the picture), I’m setting a line of moby-sized rocks. In fact, the original moby from the yard is the white rock at the center of the line. The gray stones at the left are a sort of “french drain” that runs parallel to the house. I didn’t want that drain to actually run into the tree-moat, but to provide for overflow management from the moat. That overflow is planned to happen at the near (left) end of the moby-rock line, where it adjoins the drain. The basin will be most shallow at the moby-rock end (where the ground is lowest anyway). I’m already seeing water pool there when it rains, so yay.
This is the high end of the basin, where I’ve been putting most of the digging effort. It’s about four inches deep right now. The outer ring of rocks are about grapefruit-sized or bigger, and have been pulled out of this excavation. You can almost see the shapes of more such rocks in the dirt of the hole, too. This ring is supposed to prevent the entire back yard from washing into the tree-moat, which I’m sure it will try to do in years to come.
This part of the yard is every bit as stony as the other end (where the garden bed is), and I have already hauled buckets of gravel out to the driveway and cart-loads of dirt up to fill in the paths. As I work, I explain to the tree what’s happening and what the intention is, and ask advice about various aspects of the job. Did you think it was my idea to leave the little rock ring in place? Heh. And although it’s a little too soon to tell, this may already be doing her some good: she’s showing some effort at recovery too.
I take encouragement where I can get it.