Rogue Gardeners (I Reveal a Trade Secret)
Ed Crocker

Some time ago I wrote in this column that I disapprove of trade secrets and work hard not to harbor any. I obviously forgot my purposeful neglect in revealing one of our best sales aids; the inveterate stubbornness of homeowners, landscapers and architects to abandon drip irrigation systems next their homes.

It is not just drip irrigation systems -- though they are the most likely over time to lead to disaster -- but watering of any sort next to walls and footings that holds the potential for damage.

My first experience with the phenomenon of watering the base of one's walls was nearly twenty years ago in the little community of Doña Ana, just north of Las Cruces. The old adobe church on the plaza there had been abandoned for fifteen years or so and gone derelict. A group of committed citizens had gotten together to restore the church and had contacted Cornerstones Community Partnerships, for whom I was technical director. It was clear from the beginning that one wall in particular was going to be a real challenge. It was the east wall, enclosed by a courtyard where a former priest had kept a spectacular flower garden. His finest plants, and the thirstiest ones, were against the adobe wall that had no footing.

There was another problem in Doña Ana and that was that the wall in question had an adverse height-to-thickness ratio. Where a safe ratio is 10:1 (meaning that for ten units of height there is one unit of thickness) there we had a frightening 14:1. The first thing we did was shore the entire roof.

When we started repairing the wall we discovered that the adobe at the base had been so saturated for so many years that it had lost its clay binder and nearly fifty percent of the cross section of the wall was nothing but powder. We tried very carefully to replace short sections of wall base, but to no avail. Within hours of commencing our first workday, the wall collapsed. Fortunately, it collapsed outwards and we were all inside under the safely shored roof. As we emerged from the disaster we looked like floured dumplings with saucer-sized eyes. It was truly spectacular.

I am pleased to report that that is the last collapse I have caused (in fairness to myself, however, I was working in concert with a long-dead gardening priest). But it was far from the last time I have encountered wall bases, whether adobe, frame, concrete or Rastra-block, that have been damaged by flowers. We are currently designing a fix for a house that has the implausible detail of a half-covered portal where it is the half away from the walls that is protected. Beneath the uncovered part, immediately adjacent to the bearing walls, open to snow and rain and fed by a drip irrigation system, is a stand of rapidly growing aspens. It is a very pretty detail.

I know that I will be castigated for saying this, but drip systems don't save. They don't save water because in my experience every one will, at one time or another, fail. When that happens, when a piece of sand or rust gets stuck in the solenoid valve it is not usually discovered until a vast quantity of water has escaped. Drip systems certainly don't save money when the repair costs for a settled footing are calculated.

But of course, drip irrigation systems are a convenience and I can't buck that trend. (I really shouldn't complain since they are better than advertising in terms of job sales.) And, naturally, gardeners like to have their flowerbeds right up against the wall and nothing I can say is going to change that either. The best I can do in the circumstances is offer a cautionary note:  If you are going to plant and water right next to your house, at least have an interceptor drain installed against the day you or your system goes rogue.