Zone Minutes

Bermuda and winter rye get about 3/4 inch each watering, which wets the top 6 to 10 inches. How many days to wait comes from AMWUA's month-by-month table. Rye is not watered from June through September. Seed it between October 10 and November 10. Dormant Bermuda can stay off in a rainy winter.

Weekly plant use is Phoenix-area historical reference ET for that month, times a crop coefficient, times seven days. Bermuda uses 0.73, the AZMET acceptable-turf factor. Desert trees and shrubs use 0.36. The applied amount is higher than plant use because no system is perfectly even: sprays are grossed up at 65% efficiency, rotors 75%, MP rotators 80%, drip 90%, bubblers 85%.

The plant and the month set how many inches to put down. Sprays, rotors, MP rotators, and bubblers each have a typical speed, so you do not enter a rate or a square footage. On drip, you only pick the emitter size. A bigger emitter finishes sooner.

Most valley yards are clay. Heads often put water down faster than the ground can take it, and the rest runs into the gutter. The calculator breaks a long run into shorter ones and tells you how long to wait. Skip a visit after a real soaking rain. This math does not subtract rainfall.

Germination is not the winter rye schedule. For the first 10 days, put down about a tenth of an inch, four times a day, and stop before dark. Days 11 through 21 drop to twice a day. After that, switch to the normal rye plan. Drip will not sprout seed.

Citrus uses the University of Arizona orange table, by canopy size. Grapefruit and lemon get 20% more, mandarins 10% less, and a tree growing in turf 20% more. On clay, mature drip runs every 10 days in October and November, inside UA's 5 to 10 day range. Each watering should soak at least 2 feet deep, out past the drip line.

Shrubs use the AMWUA Landscape Watering by the Numbers soak: 4 gallons for a 2-foot canopy, up to 20 gallons for 6 feet. That wets the root zone 18 to 24 inches. High-water is the safe interval for a mixed bed. Desert-adapted, including Texas sage, waits longer. The guide does not classify lantana, oleander, or natal plum. Run time is the gallons divided by the total gallons per hour on the plant.

No. These ET totals are valley-floor planning averages, on the order of 70 inches a year, in the range of the Phoenix Encanto record. Flagstaff, Payson, and even Tucson need their own numbers.