Watering a yard here, and what it does to the design

In most of the country irrigation is a top-up for what the rain did not deliver. Here it is the water supply. Laredo averages 19.68 inches of rain a year, takes a large share of that in a handful of storms, and spends the rest of the year evaporating whatever is left off an exposed lot. Anything in a Laredo yard that is not a native shrub is living on what comes out of a pipe, and that fact shapes the design rather than just the bill. It is the reason a landscape built for this city looks structurally different from one built two hundred miles east.

Where the water goes

Almost all of it goes on turf. A lawn is a continuous, shallow-rooted, evaporating surface, and it wants water on a frequency that has nothing in common with what the shrubs around it want. Every other line on an irrigation bill is small next to it. So the first question worth answering is not what to plant, it is how much lawn the household genuinely walks on. Whatever gets stood on, played on or let a dog out onto is lawn worth its water. Half an acre of Bermudagrass down the side of the house is watered every week by a household that has not set foot on it since they moved in.

That is why turf reduction is the first move on most yards here rather than a last resort. It is not an aesthetic position. It is the only change available that reduces the water demand rather than redistributing it.

Spray and drip are not the same act

A spray head throws water through the air and lands it on a surface. On a July afternoon in this city, with the daily high averaging 100.3F and wind running unobstructed across most lots, a serious share of that output never reaches root depth at all. Some evaporates in flight, some drifts onto paving, and some sits on foliage and goes back into the air by mid-morning. Drip does none of that. It meters water onto the soil where the roots are, at a rate the ground can absorb.

Follow that through and the shape of a well-built Laredo yard falls out of it. The lawn shrinks to the piece that gets used and stays on spray, because that is what turf needs. Everything else becomes planted beds on drip, running on their own schedule at whatever hour suits them. Hard surface goes wherever nothing was going to thrive anyway. None of that is a compromise forced by scarcity; it is what a hot semi-arid climate rewards anywhere in the world.

Hydrozoning, and the mistake almost every system makes

The other half of the answer is zoning. A hydrozone is a group of plants with similar water demand served by one valve on one schedule. The most common irrigation fault in this city is a single zone feeding both lawn and shrub beds, which means one run time is trying to satisfy two requirements that are not close to each other. The result is a bed that gets overwatered into root problems and a lawn that never quite gets enough, on the same bill.

1. 1 Lawn, on spray or rotary heads. The thirstiest ground on the property and the only zone that has to be watered as a surface. Its size is a decision about how much lawn the household walks on, not a landscaping rule.
2. 2 Planted band, on drip. Emitters put water into the soil at the roots, so almost none is lost to evaporation or wind. In July that difference is most of the water bill.
3. 3 Dry edge. Cenizo, sotol, agave, yucca and native grasses, watered while they root and then left to the weather. This is the part of the yard that survives a drought restriction without anyone doing anything.
4. 4 Shade on the west side of the house. Afternoon sun is the load that matters here, so a tree placed for late-day shade does more for the house than the same tree anywhere else on the lot.
5. 5 The valve boundaries. Each zone runs on its own valve. One valve serving two zones has to be set for the thirstiest thing on it, which is how a bed gets a lawn schedule and drowns while the lawn is still dry.

Splitting that zone is usually the cheapest meaningful improvement available on an existing system, and converting the bed side to drip while the trench is open costs very little extra. Published ranges put a drip conversion on one zone somewhere between $400 and $1,500 depending on bed size and access. Against a summer water bill in this city, that is not a long payback. The irrigation page covers what the work involves.

Programming a controller nobody revisits

Controllers are where good intentions go to die. Three habits make the difference.

• Use seasonal adjust rather than four separate programs. Most controllers have a percentage dial that scales every run time at once. Set the schedule for peak summer, then dial it down through autumn and winter. It is a thirty-second job that saves a great deal of water and does not require reprogramming anything.
• Give the drip beds their own program. Sharing one with the lawn means the beds get the lawn's frequency, which is several times what they want. The bed then sits wet under the mulch where nobody can see it, and the first sign of trouble is a plant dying of something that looks like drought.
• Fit a rain or soil moisture sensor. Laredo averages 19.68 inches of rain a year and takes a meaningful share of it in a handful of storms. A controller running its usual cycle the morning after 2 inches of rain is pure waste, and a sensor interrupts that automatically.

The other item worth checking on any system is the backflow prevention on the potable connection, which is what stops irrigation water traveling back toward the drinking supply. It is not something a homeowner can eyeball, and it is the part of an irrigation quote worth having named explicitly.

New plantings, and the two summers that decide them

Everything new goes on drip from day one, whatever it will eventually run on. A shrub out of a small nursery pot has a root ball the size of a grapefruit and no way to reach water outside it, and an emitter sitting on that root ball delivers exactly what it needs without wetting the whole bed to get there. A spray zone trying to do the same job waters the gaps between plants and grows weeds in them.

Establishment watering is not optional and it is not brief. Shrubs and perennials need it through their first two summers; trees need two to three growing seasons of regular deep watering. The plants on the reliable list for this region are genuinely capable of living on rainfall, but only after their roots have left the original root ball, and the most common reason a drought-tolerant planting fails is that somebody turned the water off in month three.

Watering deep and infrequently

One more principle, and it applies to every plant on the lot. Deep, infrequent watering produces deep roots. Shallow, daily watering produces a plant whose roots sit up near the surface, in exactly the layer that dries out fastest and the layer that fails first the moment a hot dry week arrives.

That means a longer run time less often, cycled if the water starts running off before it soaks in. On a well-drained sandy loam, run-off is less of a problem than it is on clay, but a compacted lawn on a scraped lot can shed water surprisingly quickly, and a cycle-and-soak schedule fixes that without any hardware.

The summary

• Turf is where the water goes. Size the lawn to what gets walked on.
• Keep spray zones to lawn people use. Put everything else in beds on drip.
• Never let one valve serve two water budgets.
• Water deep and infrequently, and cycle the run where the ground sheds it before it soaks.
• Use seasonal adjust rather than rebuilding programs four times a year.
• New plantings need two full summers of establishment water, and trees two to three growing seasons.