Landscape Irrigation: Challenges & Strategies Dennis Pittenger, M.S.

Area Environmental Horticulturist University of California Cooperative Extension Los Angeles County/UC Riverside Presentation © 2015 Dennis Pittenger

Dennis Pittenger Area Environmental Horticulturist [email protected] Phone: 951.827.3320 CENTER FOR LANDSCAPE & URBAN HORTICULTURE

• B.S. & M.S. Horticulture, Ohio State University • 34 years experience – Landscape & urban horticulture – Education and applied research programs – Landscape irrigation mgt., plant water needs, weather-based irrigation control – Presentations, workshops, publications, Web

. • Los Angeles County/UC Riverside

Objectives • Gain perspective on landscape water use. • Learn 5 steps for reducing water demand in existing landscapes. • Discuss ideas for reducing water demand at school sites and issues regarding water conservation.

• Los Angeles County/UC Riverside

Essentiality of Landscape Water • • • •

Function Recreation Aesthetics Mental Well-being

•

Los Angeles County/UC Riverside

Average California Water Use Statewide Developed Water 20% Urban & 9% Landscape

7%

Agriculture

4% 1% 3% 2%

Indoor Residential

6%

Outdoor Residential Large Landscape Comm'l/Inst'l/Inds'l Other 77%

Environmental

Sources: Calif. Dept. Water Resources, 2013 Calif. Water Plan Update Chp. 3. UCLA Inst. of Env’t. and Sustainability, So. Calif. Environ’l. Report Card, Fall 2009.

California Urban Water Use Statewide Average 1998-2005

Source: Calif. Dept. Water Resources, 2013 Calif. Water Plan Update Chp. 3

Evapotranspiration (ET)

• Los Angeles County/UC Riverside

(G.S. Sibbett and L. Ferguson. 2005. Olive production manual. Oakland: UC Div. of Agriculture & Natural Resources Pub. 3353.)

• Los Angeles County/UC Riverside

www.cimis.water.ca.gov

Reference Evapotranspiration Average ETo (in.) – Pomona, CA Mo. Wk. Day

Jan 1.95 0.4 0.06

Feb 2.35 0.6 0.08

Mar 3.67 0.8 0.12

Apr 4.62 1.1 0.15

May 5.27 1.2 0.17

Jun 5.93 1.4 0.20

Jul 6.52 1.5 0.21

Aug 6.38 1.5 0.21

Sep 4.87 1.1 0.16

Oct 3.39 0.8 0.11

Nov 2.26 0.6 0.08

Dec 1.64 0.4 0.05

Annual 48.9

www.cimis.water.ca.gov → Sign-in → DATA tab Select closest station

• Los Angeles County/UC Riverside

Food Gardens & Edible Landscapes …..Same as cool-season grass

• Los Angeles County/UC Riverside

Percent of ET Required 1.00

More Leaves & Growth High Expectations

Turf 0.80

Perennials C

0.60

W 0.40

0.20

0.00 Copyright © 2010-2015 D. Shaw and D. Pittenger

Tr-Sh-Gc

Less Leaves & Growth Low Expectations

Most landscapes have non-functional turf and have been… Overwatered!!!

From: Irvine Ranch Water District Turf Removal Rebate Program

• Los Angeles County/UC Riverside

Zero-scape (Not Xeriscape)

• Los Angeles County/UC Riverside

Available at: www.ucanr.edu/cluh

• Los Angeles County/UC Riverside

www.ucanr.edu/cluh

• Los Angeles County/UC Riverside

Prioritizing Irrigation

• Los Angeles County/UC Riverside

Prioritizing Irrigation • Focus water on most valuable & difficult to replace plants • Trees/Shrubs/Vines/Grdcvr > Perennials > Lawn/Annuals

Prioritizing Irrigation • Schedule irrigation for trees!! • Turf easily replaced

• Los Angeles County/UC Riverside

Hierarchy for Reducing Garden & Landscape Water Demand • • • • •

Improve Irrigation System Performance Improve Irrigation Management & Schedules Adjust Cultural Practices Reduce Turf Area/Alter Plant Palette Reduce Total Planted Area

• Los Angeles County/UC Riverside

Improve Irrigation System Performance The irrigation system should distribute water as uniformly and efficiently as possible

• Los Angeles County/UC Riverside

• Los Angeles County/UC Riverside

Distribution Uniformity (DU) DU 0.5 0.6 0.7 0.8 0.9

Irrigation Multiplier 2.00 1.67 1.43 1.25 1.11

• Los Angeles County/UC Riverside

Improve Irrigation System Performance Fix Obvious Problems

Improve Irrigation System Performance Effective Irrigation Controllers • Minimum 3 programs • Minimum 4 start times • Interval or day of week option • Station for each zone • Rain shutoff • Global % adjustment • Los Angeles County/UC Riverside

Hardware Improvements • • • • • •

No silver bullets – smart controller? 4+ programs/4+ starts/Global adj. Precision, Press. Comp. emitters 1 station per zone Rain shutoff & rain sensor Drip irr. non-turf areas

Improve Irrigation Management & Schedules • • • • • •

How much? How often? Irrigate 12 AM – 6 AM Set July runtime & cycles How much? How often? Adjust schedules monthly Use global % adjust

• Los Angeles County/UC Riverside

Avoid Runoff & Overspray • Cycle and soak • Run irrig. lines across slope • Low precip. heads & e heads

• Los Angeles County/UC Riverside

Estimated Irrigation Req’ts. Irrigation Calculators: www.ucanr.edu/cluh • Increase runtimes for system inefficiency

• Los Angeles County/UC Riverside

www.ucanr.edu/cluh

Easy Calculators

• Los Angeles County/UC Riverside

Improve Irrigation Management & Schedules Deficit Irrigate by up to 30% (short term) • Extend time between irrigations • Wet entire root zone • Trees, shrubs, groundcovers tolerate well • Cool-season grass less tolerant

• Los Angeles County/UC Riverside

Adjust Cultural Practices • Aerate turf • Raise mowing height • Reduce fertilizer – Slow release N

• Mulch exposed soil • Avoid heavy pruning

• Los Angeles County/UC Riverside

Reduce Turf/Alter Plant Palette • Functional turf only – Play & walk-on surfaces – Erosion, mud, dust control – Cooling

• Separate irrigation zone

• Los Angeles County/UC Riverside

Not Hydrozoned • •

Hydrozoned • Turf irrigated separately • Part 50%, part 80% ETo

Trees irrigated with turf All 80% ETo

Reduce Planted Area

Photo Credit: Larsen Landscape

• Los Angeles County/UC Riverside

Considerations When Reducing Planted Area • Potential Pros – Less water demand – Less maintenance – Similar cooling

• Potential Cons – Similar maintenance – Increased heat – Increased erosion – Altered habitat – Expensive to install

• Los Angeles County/UC Riverside

Take Home - Highest ROI Priorities • • • • • •

Prioritize irrigated areas Evaluate/adjust expectations Improve irr. sys. performance Landscape & irr. sys. maint. Improve irr. mgt. & schedules Reduce planted area

• Retrofit/adjust plant spp. mix

• Los Angeles County/UC Riverside

Questions???

• Los Angeles County/UC Riverside

Useful Equations Inches = Gallons ÷ (Sq. Ft. × 0.623)

Gallons = Inches × Sq. Ft. × 0.623 1 gal. covers 1 sq. ft. with 1.6 in. of water 1 Billing Unit = 100 cubic ft. = 748 gallons (1 sweep of meter needle = 7.48 gallons) 𝐢𝐧. 𝐨𝐫 𝐠𝐚𝐥. 𝐧𝐞𝐞𝐝𝐞𝐝 × 𝟔𝟎 𝐑𝐮𝐧𝐭𝐢𝐦𝐞 𝐌𝐢𝐧𝐮𝐭𝐞𝐬 = 𝐢𝐧. 𝐨𝐫 𝐠𝐚𝐥. 𝐚𝐩𝐩𝐥𝐢𝐞𝐝 𝐩𝐞𝐫 𝐡𝐫. × 𝐞𝐟𝐟𝐢𝐜𝐢𝐞𝐧𝐜𝐲 %

• Los Angeles County/UC Riverside

Dennis Pittenger Area Environmental Horticulturist [email protected] Phone: 951.827.3320 Center for Landscape & Urban Horticulture

• Los Angeles County/UC Riverside