What is Hydrozoning?

Hydrozoning sounds like the reason you get jittery on slippery roads, but it’s actually a water-wise landscape design that benefits your plants and the planet. Whether you live in a dry climate, want to conserve water, or wish your flowers would stop drowning when you water your grass, hydrozoning could be the perfect solution.

So grab a glass of ice water (it’s important to hydrate yourself, too!), and let’s dive into what makes hydrozoning a sustainable landscaping choice.

What is hydrozoning? 

Hydrozoning is the landscape design practice of clustering together plants with similar water, sun, and soil requirements to conserve water and improve plant health. It minimizes both underwatering and overwatering, which means happier plants and less water waste. When done correctly, a hydrozoned lawn can reduce your water use by 20% to 50%.

Hydrozoning is one of the key principles of xeriscaping (creating a drought-friendly landscape). It means you can focus on watering specific areas of your lawn or garden and feel confident that the other parts will stay healthy. 

5 steps to start hydrozoning

Here’s how to design your own hydrozoned lawn. 

1. Draw a bubble map

Brainstorm how you want to hydrozone your lawn by drawing a bubble map of your yard, including where you want grass, a flower or veggie garden, a rock garden, or any other major yard element. 

Observe your lawn over a few days. Take note of the sunlight, water, and slope profile of different areas.

• How much sunlight do different portions of your lawn receive?
• Do you have shady areas where grass doesn’t grow? 
• How does rain flow across your lawn? 
• What areas get the most and least water?
• Are there hills or slopes that dry out quickly?
• Do particular areas of my lawn have more sandy, silty, or clay soil? 

Design your bubble map based on how your yard naturally functions. You want to work with your topography, not against it. A shade garden can fit perfectly in a dark, moist corner of your yard where other plants won’t grow. Likewise, sunny, sandy slopes with southern exposure may dry up too easily for turfgrass, but a wildflower garden will thrive.

If you hand-water your lawn, place plants with high water requirements close to your house so you don’t have to trek to the back of your lawn with a hose twice a week. Make the back corners of your lawn more desert-like, choosing plants with lower water requirements. 

Decide which plants you want to keep and which don’t belong in your new landscape. Include landscape elements that won’t change (like trees, patios, decks, and sidewalks) in your bubble map.

This is just your first creative step, so have fun choosing your dream lawn design! Play around with the size and shape of each hydrozone area. You can always change your bubble map to make your design more water-friendly. 

Pro Tip: If you have sprinkler lines installed, keep them in mind as you design. Each bubble should have its own sprinkler line. (More on that in Step 4.)

2. Divide your lawn into irrigation zones

Think of your lawn as having four hydrozones. These zones tell you where you can go easier on the water and where you need to let it flow. 

The four zones are the: 

• Routine irrigation zone
• Reduced irrigation zone
• Limited irrigation zone
• Non-irrigated zone

With your bubble chart in hand, match up each bubble with the type of zone that corresponds with its design goal and level of use. For example, you would label your native plant garden a limited irrigation zone.

Routine irrigation zone

The routine irrigation zone (aka the principal irrigation zone) is the part of your lawn that gets the most use and requires the most frequent watering: Twice a week or more.

The routine irrigation zone is made up of turfgrass and water-loving shrubs and trees. If you use your backyard frequently for hosting, or if your kids play on it, it will probably be a routine irrigation zone.

Plants for the routine irrigation zone: 

• Durable turfgrass like Kentucky bluegrass
• Water-loving trees and shrubs like cottonwood, eastern red cedar, and elderberry bush
• Vegetables and small fruits

Water needs: 

Twice a week or more (18 gallons of supplemental water per square foot per year). 

Reduced irrigation zone

This area (aka the secondary irrigation zone) does not get as much human use as the routine irrigation zone, but it occupies a prominent visual space. Shrubs and flower beds close to your home are often a part of the reduced irrigation zone; they tend to require weekly watering and the soil must be kept moist. 

Plants for the reduced irrigation zone:

• Flower beds with flowers like columbine and anemone
• Eye-catching shrubs 
• Some trees like arborvitae
• Fruit trees

Water needs: 

About every 7 to 10 days (10 gallons of supplemental water per square foot per year). 

Limited irrigation zone

Known as the minimal hydrozone, this is the part of your lawn that gets little human use and has low water requirements. The corners of your lawn, strips of grass between the street and sidewalk, and the area around your fence line are often limited irrigation areas. The limited irrigation zone contains hardy plants that need watering only during dry spells. 

Plants for the limited irrigation zone: 

• Native plants like potentilla and purple coneflower
• Drought-tolerant grass like tall fescue (goes dormant during summer)
• Ground covers like blue catmint and creeping thyme
• Some mixed flower and shrub beds

Water needs: 

During dry spells once plants are established (3 gallons of supplemental water per square foot per year). 

Non-irrigated zone

The non-irrigated zone (aka the elementary hydrozone) gets all its water from rainfall and requires zero supplemental watering. It includes the spots around utilities, mulched areas, and natural vegetation.

Plants for the nonirrigated zone:

• Native plants like yarrow and rabbitbrush
• Buffalograss (goes dormant during summer)

Water needs: 

No irrigation (0 gallons of supplemental water per square foot per year). 

3. Refine your design

Now that you’ve mapped out your zones, you may want to amend your lawn design so that more of your yard needs less water. 

Ask yourself if there are grass areas where you can replace Kentucky bluegrass and other high-water grasses with lower-water grasses like buffalograss and blue grama. Consider building some beautiful flower beds where you initially planned turfgrass. Hydrozoning isn’t anti-turf: It’s just about using turf wisely and limiting it to where it’s needed.

Remember to keep existing sprinkler lines in mind when designing. For hydrozoning to work, each zone must be watered by a separate irrigation valve to get the right amount of water on the right schedule. 

If thirsty Kentucky bluegrass and hardy native flowers are on the same sprinkler line, it defeats the purpose of hydrozoning: If you water based on Kentucky bluegrass’s needs, native flowers will drown, and if you water based on native flowers’ needs, Kentucky bluegrass will dry out.

4. Plan your irrigation system

You can hydrozone no matter what type of irrigation system you have, whether you water by hand, have sprinklers, or use a drip or bubbler system. 

However, with poorly planned irrigation systems, gardeners apply twice the amount of water plants actually need. A well-placed irrigation system saves you from this watery mess. 

• Drip irrigation systems are perfect for mixed flower and shrub beds, perennials, small fruits, and vegetables. These irrigation systems deliver water directly to plant roots, so you minimize water loss from evaporation. Drip irrigation is best for smaller or irregularly shaped spaces, and most drip irrigation systems cost $295 to $775.

• Sprinklers are best for large trees and expansive turfgrass. The spray from each sprinkler head should reach or overlap neighboring sprinkler heads to ensure uniformity in water coverage within each zone. It’s best to have an overlap of 10% to 20%. Most sprinkler systems cost $2,400 – $4,200.

Many irrigation systems are set to water your entire lawn on the same schedule and at the same depth, which means trees, grass, and garden plants all get the same amount of water at the same time, no matter how much water they really need. 

If you’re using sprinklers, then each hydrozone must be on a separate irrigation valve so you can customize the watering schedule and depth based on different plant requirements. 

Pro Tip: To minimize water waste, avoid sprinkler irrigation on spaces less than 5 to 10 feet wide.

5. Pick your plants

Here’s the fun part! Choose beautiful plants based on the water, soil, and sun requirements of each hydrozone. Your local nursery or cooperative extension office is a great resource for information on the best plants for dry, wet, sunny, and shady areas. 

As you pick out plants, think about how their needs fit within the hydrozone: Sure, petunias are gorgeous, but their watering needs don’t match with coneflowers and other drought-tolerant plants, so they don’t belong in your limited irrigation zone. Remember, hydrozoning is all about grouping plants with similar water needs.

Native plants are the real heroes of hydrozoning. Native plants naturally thrive in your region, so they don’t need fertilizer, pesticides, or watering once established. Plus, they attract butterflies and bees, so you can forget the hose and enjoy a colorful show outside of your window. Explore your options using the National Wildlife Foundation’s native plant finder. 

Once you’ve designed your ideal hydrozoned lawn, begin the grass removal process to give native plants a fresh place to grow. 

Where to hydrozone

No matter where you live in the U.S., you can hydrozone within your garden or throughout your landscape. No matter how small your space, hydrozoning helps save water and keep your plants healthy. 

Hydrozoning benefits

• Lower maintenance than a full grass lawn: By confining your grass to one hydrozone and adding more native plants, shrubs, and wildflowers to the rest of your yard, you’ll have less mowing, fertilizing, and watering to do.

• Water-efficient: Reduces landscape water use by 20% to 50% to protect the environment and prevent waste.

• Saves money: You don’t have to spend as much money on water, expensive chemical treatments, and plant replacements. 

• Rebates: You may be eligible for savings if you xeriscape.

• Saves time: Simplifies your watering work.

• Reduces polluted runoff: The deep roots of native plants and drought-tolerant shrubs reduce erosion and runoff during storms.

• Uses fewer chemicals: Native plants require no fertilization or pesticide, and healthy non-native plants don’t need as many chemicals as overwatered or underwatered ones.

• Streamlines your lawn: Limit your grass without going grassless.

FAQ about hydrozoning

Hydrating with hydrozoning

Hydrozoning is the solution to accidentally waterlogging your wise old oak tree while trying to give your thirsty grass the water it needs. You can DIY your own hydrozoned lawn, or sit back, sip a refreshing ice water, and let your lawn get the special treatment from a local team of lawn care experts.

Main Photo Credit: California Bureau of Land Management | Flickr | (CC BY 2.0)