Water-wise gardening in Palo Alto

Palo Alto's climate is kind to gardeners in most ways. Frost is light, summers are warm and sunny and something is in bloom every month. The catch is water. NOAA's normals for the Palo Alto station put annual rainfall at about 15 inches and almost all of it falls between November and April. From May to October a garden lives on whatever you give it. That water comes from the Sierra Nevada by way of Hetch Hetchy.

A water-wise garden is built around that pattern. It groups plants by thirst, waters deeply but rarely, keeps soil covered and leans on plants that evolved for dry summers. Done well it uses a fraction of the water of a lawn and still looks good in August. This guide covers the rules, the techniques and the free help available. For the bigger picture of where Palo Alto's water comes from, see our water conservation guide.

The watering rules that apply

Palo Alto's permanent water use rules sit in Chapter 12.32 of the municipal code and apply in wet and dry years alike. Section 12.32.010 is the one gardeners meet most often:

• No midday watering of lawns or purely decorative landscaping with drinking water between 10 a.m. and 6 p.m.
• Exemptions to the hours rule for trees, edible gardens and hand watering with a bucket or a hose with a working shut-off valve.
• No runoff into gutters, driveways, sidewalks or streets.
• Prompt repairs of broken sprinklers and leaking irrigation lines.

The code does not assign watering days. During a declared shortage the city can add tighter limits, so watch for notices from City of Palo Alto Utilities in a drought year. The state's ban on watering nonfunctional turf, which starts in 2027, applies to public, commercial and HOA land. The city says single-family yards are excluded.

Group plants by thirst

The biggest waste in most yards is a single irrigation schedule for everything. A lawn, a rose bed and a row of rosemary all get the same 10 minutes, so the rosemary drowns while the lawn still browns at the edges. Landscape designers fix this with hydrozones, which simply means putting plants with similar needs on the same valve.

Keep the thirsty zone small and close to the house or the kitchen door, where you see it. Put the toughest plants at the far edges and in hot west-facing strips. Our native plants guide lists where to buy local species that fit the very low zone.

Irrigation that wastes less

Drip for beds and shrubs

Spray heads throw water into the air, onto paths and over leaves. Drip lines and emitters put it at the roots. Most beds, foundation plantings and new native gardens do well on drip. In-line drip tubing, with emitters built in at a set spacing, suits dense plantings. Point emitters suit widely spaced shrubs. Add a filter and a pressure regulator at the valve, flush the lines once a year and check for chewed tubing, since squirrels and rats sometimes bite drip lines in summer.

Rotating nozzles for lawn that stays

If you keep a patch of lawn, high-efficiency rotating nozzles apply water more slowly than old fixed sprays. That cuts runoff on Palo Alto's heavier clay soils. Running each zone in two or three short cycles with a break between them, often called cycle and soak, helps even more.

A controller that reads the weather

Weather-based or smart controllers adjust run times to temperature and rain. The single most useful setting is the one many people forget: turn automatic watering off after the first soaking storms in fall and leave it off until spring. Our weather guide shows when the rain usually arrives.

Free help: the Water Wise Outdoor Survey

Valley Water, the Santa Clara County water district, runs a free Water Wise Outdoor Survey. A trained irrigation professional visits, runs the system and flags problems such as broken heads, overspray and schedules that run too long. You get recommendations for repairs and upgrades, some of which may qualify for rebates.

• Who qualifies: single-family, multifamily and commercial properties in Santa Clara County with landscapes under half an acre and a valve-operated irrigation system.
• Who does not: yards watered only with a hose or a portable sprinkler.
• What it does not include: surveyors do not make repairs or hunt for underground leaks, though they can help tell an indoor leak from an outdoor one.
• How to book: the online request form or (408) 630-2000.

Surveyors can also hand you a do-it-yourself indoor survey kit on request. Pair the visit with the city's WaterSmart portal, reached through MyCPAU, which shows hourly use on smart meters. A jump at 3 a.m. on watering days is your irrigation; a steady line all night may be a leak.

Equipment rebates

Valley Water's Landscape Rebate Program pays toward several water-saving upgrades. The city lists it on its Ways to Save page as the route for Palo Alto residents. The program covers:

• Irrigation equipment upgrades, including weather-based controllers, rain sensors, high-efficiency nozzles and flow sensors from Valley Water's qualified lists
• In-line drip conversion of existing spray zones
• Landscape conversion of lawn, covered in our lawn replacement rebates guide
• Rain barrels, cisterns and rain gardens, covered in our rain barrels and graywater guide

Valley Water's main page did not list per-item amounts for irrigation equipment when we checked in November 2026, so look them up in the online portal. Two rules matter more than the amounts. First, apply and wait for written approval before you buy or install anything. Second, funding runs until June 30, 2027 or until it runs out, with applications handled in the order received. The conservation hotline is (408) 630-2554.

Soil and mulch

Much of Palo Alto sits on old orchard and creek-plain soil that leans toward clay. Clay holds water well but drains slowly, so frequent shallow watering keeps the top inch soggy while deeper roots stay dry. Water longer and less often and let the surface dry between sessions.

Mulch does more for a dry garden than almost anything else. A layer of wood chips or shredded bark, about 2 to 3 inches deep, keeps soil cool, slows evaporation and smothers weed seedlings. Keep it a few inches back from stems and tree trunks to avoid rot. Arborists often give away chips from local jobs. Avoid plastic sheeting under mulch: it starves the soil of air. Valley Water's landscape conversion rules no longer allow plastic weed barriers either.

Leaves are mulch too. Instead of bagging them, rake them under shrubs. Gas leaf blowers are banned in residential areas, a rule explained in our leaf blowers and noise guide.

When to plant

Fall is planting season in Palo Alto. Soil is still warm in October and November, winter rain waters new roots for free and by May the plants have a head start on the dry months. Late winter suits bare-root fruit trees and roses. Spring planting works but expect to water new plants weekly through their first summer.

1. October to December: plant natives, shrubs, perennials and trees. Turn irrigation off after soaking rain.
2. January to March: plant bare-root fruit trees, prune deciduous trees and check drip lines before growth starts.
3. April and May: restart irrigation gradually as the soil dries. Refresh mulch.
4. June to September: water deeply in the early morning. Watch new plantings closely during heat waves.

Pruning a large tree in a dry spell? Check the rules first. Many trees in Palo Alto are protected and need notice before work, as our tree permits guide explains.

Where to learn more locally

Valley Water runs free webinars through the year. Its spring 2026 lineup included sessions on finding outdoor leaks, garden design and rethinking the lawn. The city has also hosted Landscape Conversion 101 sessions, listed on its events calendar. For inspiration in person, Gamble Garden shows mature plantings in Old Palo Alto. Nurseries in and near town are listed in our garden centers guide. If you want to grow food without a yard, our community gardens guide explains the city's plots.

Frequently asked questions