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Janet Hartin
Environmental Horticulturist
Keeping Plants Alive Under Drought and Water Restrictions in the
Coachella Valley
Sustainability
“meeting the needs of today’s
population without diminishing the
ability of future populations to meet
their needs.”
Why Garden Sustainably?
Save
Money
Improve Garden Health
Protect
Water Quality and Wildlife
Sustainable Landscaping……
Leaves a greener footprint for our children’s children
Sustainable Landscapes
• Incorporate plants suitable for climate/location
• Conserve water
• Nurture and protect soil
• Prevent/reduce pest problems
• Conserve energy/Reduce pollution
• Encourage wildlife
Select plants recommended for your Sunset Zone
And
Microclimate
USDA Zone 9
(Not As Specific As Sunset Zones)
Sunset Zones Are Smaller and More Accurate
Riverside County Includes Zones 13 (desert) and 18 and 19 (valley cities) Let’s Look at Drought Efficient Examples for Sunset Zone 13 (Coachella Valley)
Acacia pravissima
(small tree) - Yellow flowers
- Attract birds
- Fast growing
Acacia rigidula
Blackbrush acacia
(Shrub or small tree) ‐ Tolerates heat and drought but also irrigation seepage from nearby lawns
‐ Bark and foliage nice contrast Grevillea ‘Canberra Gem’
(shrub or small tree)
‐ Bright red flowers In spring
‐ Relatively disease and insect resistant
Parkinsonia hybrid ‘Desert Museum’ (Palo Verde)
‐ Excellent thornless , sturdy specimen tree ‐ Grows to 30’
‐ Deep yellow flowers
Fremontodendron californicum
(shrub or small tree)
‐ Yellow flowers in spring
‐ Fast growing
‐ Glossy green foliage
Acacia redolens ‘Prostrata’
Prostrate Acacia
(groundcover)
‐ Grows to 1‐2’ tall, spreading
‐ Rapid coverage for slopes
‐ Great for erosion control
Wedelia trilobata
Yellow Dot
(Groundcover)
‐ Rapid spreading to 1‐1/2’ high and 6’ wide
‐ Dark green leaves accentuate yellow flowers in summer
‐ Takes some shade
Shade, wind, poor soil, power lines, etc.
Sustainable Landscapes
Conserve Water Through:
1. Hydrozoning 2. Scheduling irrigations based on plant needs
3. Making sure sprinklers/drip systems work properly
4. Using mulch and soil amendments effectively
Hydrozoning: Placing plants with similar water needs in the same irrigation zone
Plant Water Use
• Varies Among Species
• Influenced By Climate and Microclimate (as previously discussed)
• Varies by Density of Planting
Adjusting your irrigation timer seasonally can save a lot of water and keep plants healthy!
(‘Smart” controllers are only as smart as the dummy who programmed them.)
Monthly Reference Evapotranspiration (ETo) (water used by cool season turfgrass) 12
Reference Evapotranspiration (in./mon)
Palm Springs
Riverside
10
San Francisco
8
6
4
2
0
Jan
Feb
Mar
Apr
May
Jun
Jul
Month
Aug
Sep
Oct
Nov
Dec
Maximum Applied Water Allowance (MAWA) = (ETo) (0.7) (LA) (0.62)
ETo = Reference Evapotranspiration (inches per year)
0.7 = ET Adjustment Factor
LA = Landscaped Area (square feet)
0.62 = Conversion factor (to gallons)
*Maximum Applied Water Allowance = _______ gallons/year
Example of Maximum Applied Water Allowance (MAWA):
Hypothetical Landscape Area = 5,000 sq ft
MAWA = (Eto) (0.7)* (LA) (0.62)**
MAWA = (71.5) (0.7) (5,000 sq ft) (0.62)
MAWA = 155,155 gallons per year
*ET Adjustment Factor ** Conversion factor from inches to gallons
‐ High water using plants use as much water as cool season grass.
‐ Medium water using plants use about 30 percent less.
‐ Low water using plants (drought tolerant) use 50 ‐ 90 percent less. Low, Medium and High Water Use Hydrozones
Drought Efficient Landscape (requires regular water until established
(first season) then cut back
Consult these Resources for Help Determining Irrigation Needs of a Wide Range of Plants:
Water Use Collection (UCD)
‐ http://ucanr.edu/sites/WUCOLS/
‐ Local Water Districts
http://www.cvwd.org/ http://www.dwa.org/
‐ Living Desert/Wellness Park, etc.
http://www.livingdesert.org/
http://www.dhcd.org/Wellness‐Park
Water Needs of the Same Species
are Higher in Heat Islands
• Landscape plants in heat islands require up to 50% more water than the same species in a park setting
The Denser The Planting, the More Water it Needs
Examples of Dense landscapes
Examples of Low Density Landscapes Requiring Less Water than Denser Ones
Water an inch or Two Below the Current Root Zone to Draw Roots Down
‐ Avoid runoff (common in heavy clay soils)
‐ Avoid losing water below the root zone (common in sandier soils)
Irrigate Established Plants Less Often But Deeper Than Newly Planted Ones
(Most overwatering occurs in established landscapes while most underwatering occurs in newly planted landscapes)
Monitor Soil Moisture with a Probe, Trowel, or Straightened Metal Coat Hanger
Drip systems apply water directly into root zones, reducing soil evaporation. They are recommended for non‐turf/groundcover plantings. Irrigate outward in the root zone of the plant (left). Incorrect (right). Keep plant crown dry. Sprinkler systems are recommended for irrigating turf and groundcovers but need to be checked regularly for problems such as:
•
•
•
•
Broken heads
Sunken heads
Non‐vertical heads
Wrong spacing
Irrigation system wastes more
water than the lawn
Warm‐Season Lawns (Bermuda, Buffalo) Use Less Water than Cool‐season Lawns
(Tall Fescue, Rye) Lawn Watering Guide for California
http://ucanr.org/freepubs/docs/8044.pdf
Misleading advertising – cool season grass uses 25 percent or more water than warm season grass and neither are low maintenance.
If you have a lawn, grasscycle or compost clippings! • Saves time/money
• Adds organic matter to lawn
• Recycles nutrients
• Reduces greenwaste
in landfills
Water cycling may be necessary to avoid run‐off when using sprinklers. Divide the total amount of water required per day into 2‐4 cycles applied closely together before soil dries out. If you’re no longer using and enjoying your lawn, consider replacing it
with a lower maintenance, drought tolerant alternative.
Turf is a poor choice in small and oddly shaped areas and on slopes!
Consider replacing turf with low maintenance drought efficient alternative groundcovers
Acacia redolens ‘Desert Carpet’
Baccharis ‘Centennial’
Dalea greggii
Other Methods to Conserve Water in the Landscape
Minimize the use of water to clean sidewalks and driveways
Remove weeds that compete with
landscape plants for water
Improve waterholding capacity
and/or drainage
with compost
mixed evenly into
soil
(6” – 1’ deep)
Don’t Let Water Get Away!
Permeable surfaces
Infiltration Basins
Water Collection
Consider Recycling Graywater (‘laundry to landscape’ systems) on non‐edibles
Apply Mulch Around Plants
Mulch Conserves Water and Beautifies Landscapes
Keep mulch several inches away from tree trunks and avoid volcanoes! Avoid Over‐fertilizing (non edibles need very little)
• Creates flushes of weak growth
• Increases water requirement
• Leads to waterway pollution
Runoff contributes to pesticide and nitrate/phosphate pollution in our waterways
Following are Suggested Methods To
Maintain Various Landscape Plants
During Water Restrictions and Severe
Drought
Trees and Shrubs
(prioritize them over flowers/lawns)
• One or two deep irrigations with a garden
hose several weeks apart in spring and
summer will often keep these valued plants
alive through summer
Fruit and Nut Trees
• Keeping them alive and
producing fruit may not
be possible.
• To produce a good crop,
deciduous fruit and nut
trees need adequate
water in their root zones
continuously from
bloom until harvest.
Vegetables
• Vegetables are difficult to
maintain during a drought.
• Water is most critical from
seedling stage through root
establishment and during
flowering and fruiting.
(Con’d)
• Tomatoes, beans, and root
crops such as carrots require
regular watering and are not
drought tolerant.
• Vine crops such as squash
and zucchini often fare
better and can be kept alive
with a few waterings once or
twice a week through the
season.
Groundcovers
• Groundcovers often survive on
about half the amount of water
received under optimal
conditions.
• To avoid serious drought stress
non-native thirsty
groundcovers need irrigation
monthly spring through fall.
Yellow Dot
Lawns (maybe it’s time to switch?)
• Traditional warm-season lawns (bermuda and
buffalograss) are more drought-resistant than cool
season grasses (ryes and tall fescues) and may come
back after several weeks of dryness.
• Reduce irrigation to ½ of recommendations in the
UC lawn watering guide
(http://anrcatalog.ucdavis.edu/pdf8044.pdf)
Thank you!
Janet Hartin Email: [email protected]
Phone: (951)313‐2023
Coachella Valley MG Helpline:
Ph: (760) 342-6437
E-mail: [email protected]