Why drip beats spray in the desert
Spray heads throw water into hot, dry air, across rock and onto walls and sidewalks. A large share can evaporate or run off before it ever reaches a root. Drip emitters drip water onto the soil above the root zone, where it soaks down slowly. Weeds in the open spaces between plants get less water, and you are not paying to water rock.
Emitters: matching water to the plant
Emitters are rated in gallons per hour (GPH), commonly 0.5, 1 or 2 GPH. The goal is to give each plant the right amount of water based on its size and needs.
- Small shrubs and groundcovers usually start with one or two emitters.
- Larger shrubs need more emitters spread around the root ball.
- Trees need several emitters, placed in a ring that grows outward over time.
- Cactus and most succulents need little, and some established ones need no regular drip at all.
Place emitters over the root ball at planting so water reaches the roots that are already there. As plants grow, roots spread outward toward the edge of the canopy. Move emitters outward and add more over the years. A five-year-old tree with emitters still hugging the trunk is a common reason for shallow roots and poor growth.
Zones: group plants by water need
Putting trees, shrubs and cactus on the same valve forces a compromise that overwaters some plants and underwaters others. Grouping plants with similar needs onto separate zones, sometimes called hydrozoning, lets each run on its own schedule:
- Tree zone: long, infrequent runs for deep watering.
- Shrub and groundcover zone: moderate runs, somewhat more often.
- Cactus and succulent zone: occasional runs, or none once established.
- Citrus or other higher-water plants: on their own zone if possible.
When designing a new landscape, we place plants with this in mind so the existing zones can be used efficiently.
How deep to water
The run time on your controller matters less than how deep the water goes. Commonly cited targets for desert landscapes are roughly:
- Trees: about 24 to 36 inches deep
- Shrubs: about 18 to 24 inches deep
- Groundcovers, cactus and small succulents: about 8 to 12 inches deep
To check, run a zone and then push a long screwdriver or metal soil probe into the soil about an hour later. It slides easily through moist soil and stops at dry soil. Adjust run time until you reach the target depth, then let the soil dry between waterings. Deep, infrequent watering trains roots to grow down, where soil stays cooler and moister.
Change your timer with the seasons
The single biggest water waste in Valley yards is a controller set for July and left that way all year. Run time, the amount applied each cycle, generally stays similar across seasons. What changes is frequency, how many days pass between cycles.
- Summer: the most frequent watering of the year.
- Monsoon: skip cycles after a good soaking rain, and turn the system back on once soil dries.
- Fall: gradually stretch the days between waterings as temperatures drop.
- Winter: the least frequent watering. Many established desert plants need water only occasionally.
- Spring: gradually increase frequency as heat returns.
Valley water providers publish seasonal watering guidelines, and they are a helpful reference. Newly planted material needs more frequent water than established plants during its first year or two, so start on the generous side and taper as plants settle in. See our tree watering guide for tree-specific schedules.
Simple maintenance that keeps drip working
- Walk each zone while it runs a few times a year and look for missing, clogged or blown-off emitters.
- Watch for soggy spots or water bubbling up, which may mean a leak.
- Clean the filter regularly; hard Valley water and debris clog emitters over time.
- Flush the ends of drip lines periodically to clear sediment.
- Check that plants look healthy. Wilting in the morning or yellowing can mean too little or too much water, so probe the soil before adjusting.
How Three Timbers helps
When we design and install xeriscapes, we give guidance on optimizing your irrigation to cut water use: how plants should be grouped, where emitters belong for new plantings and how to adjust your schedule through the year. Xeriscape design and installation are back on our schedule now, beginning with a consultation walk of your property, then an MCAD design, then installation. If you are replacing turf, our grass to desert conversion page explains the full process. We back our work with a 100% satisfaction guarantee. If you're not absolutely satisfied with our service, simply let us know, and we will work tirelessly to make it right.
Plant smart, water less
Shop low-water desert perennials and natives at threetimbersshop.com and add planting at checkout. For a new xeriscape design and installation, with irrigation guidance included, call (612) 214-1955 to request a quote.
Frequently Asked Questions
How long should I run my drip system in Phoenix?
It depends on emitter size, soil and plant type. Run a zone, then probe the soil to see how deep water reached. Aim for roughly 24 to 36 inches for trees and 18 to 24 inches for shrubs, and adjust from there.
How often should I change my irrigation timer?
Adjust at least with each season. Keep run times similar, and change how many days pass between waterings: most frequent in summer, least frequent in winter, and pause after soaking monsoon rains.
Should I move my drip emitters as plants grow?
Yes. Roots spread outward toward the edge of the canopy, so move emitters outward and add more as plants mature, especially for trees.
Should cactus be on the same drip zone as trees?
Ideally not. Cactus and succulents need far less water than trees and are prone to rot when overwatered. Separate zones let each group get what it needs.
Does Three Timbers install irrigation systems?
Our role is guidance. As part of our xeriscape consultations and installs, we advise on grouping plants, emitter placement and seasonal scheduling to help you get the most from your system and cut water use.
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