Commercial Irrigation Design Support

Hydrozoning, which is the whole idea

A hydrozone is a group of plants with similar water needs, watered together. It is the concept that separates a system that can be tuned from one that can only be compromised.

When turf and shrubs share a zone, there is no correct run time. Turf wants frequent shallower watering, shrubs want deeper and less often. Whatever the schedule, one of them is wrong every week.

Sun and shade matter as much. The same plant in full afternoon sun and in building shade needs meaningfully different water, and on one zone the shaded area is permanently over watered.

Getting this right at design costs nothing extra. Fixing it afterwards means moving valves and pipe, which is why it so rarely gets fixed.

If turf and shrubs share a zone, there is no run time that is right. One of them is wrong every single week.

What to ask a landscape designer about water

Irrigation is usually an afterthought in a landscape design, which is how properties end up with beautiful planting on a system that cannot serve it.

Four questions catch most of the problems. How are the zones grouped and why. What is the assumed pressure and has it been measured. How does this planting get watered through establishment, which is different from how it gets watered afterwards. And what does this design cost to run in water per year compared with what is there now.

The last question is the one designers are least often asked and the one property managers care most about after the first bill.

Designing changes into a system that already exists

Most commercial irrigation work is not a new system. It is changing an existing one to suit planting that has changed around it.

The most common case is a turf conversion. Turf comes out, low water planting goes in, and the spray heads stay. Spray on a turf schedule then drowns a planting that wanted a quarter of the water. Six months later the planting is dead and the bill has not moved.

A conversion is an irrigation project with plants attached. Converting the zone to drip is the work, and the planting is the visible part.

The second common case is a bed that has grown in. Shrubs planted at nursery size now block the spray they were designed around, so the back of the bed is dry while the front is soaked. That is a head placement problem that gets treated as a watering problem.