Dear
Bethany:
For
many, watering seems to be the hardest subject to figure out.
There are many factors like sun exposure,
soil types, the rate of soil percolation, plant types, plant
maturity, and most importantly, the type of irrigation system
you have installed.
Soil
types like calachi or clay will require less water than sandy
loam or decomposed granite. Most of the valley soil has areas
of sandy loam, clay, and calachi. So, depending on the soil
types you plant in, you may have to monitor the moisture content
for a few weeks to adjust the timer for a perfect watering schedule.
With
the development of drip irrigation and digital controllers,
watering has become more
efficient.
The new controllers will allow skip day options as well as percentage
use controls. Drip
emitter’s
allow water to be placed directly in and around the root zone
with little or no waste. Watering should occur in the early
am hours when winds and evaporation are lowest. As the sun warms
the air, the plant will absorb water and transpire (this is
called trans‑evaporation) causing healthy vigorous growth.
There is no need for several waterings per day. The only time
watering should be scheduled several times a day is during the
seeding process to keep the surface layers moist.
I
recommend installing emitters based on plant size and type.
I also recommend using a one hour schedule minimum and using
the skip day mode to reduce watering schedules versus reducing
the time itself.
Emitter
schedule
1- 1 gallon emitter per 1 gallon shrub
1- 1 gallon emitter per 5 gallon shrub
3 -2 gallon emitters per 15 gallon tree
4- 2 gallon emitters per 24” Box tree
6-2 gallon emitter per 36” Box tree
NO
emitters to cacti or agaves. If hand watering cannot be completed,
place a 1 gallon emitter 1 to 2 feet from the cacti or agaves
root zone.
Drip
systems around trees should be looped near a mature drip line
(the area where the tree canopy reaches at maturity) and the
emitters should be placed by way of ¼” poly tube close to the
new root ball. As the tree matures, cut back the emitter lines
to the new canopy area. I find that the Rainbird® Xeribug emitters
work best because they can be placed in the primary 5/8 poly
tube and the ¼” extension tube can be placed near the root zone.
As the tree grows, the ¼” tubing can be cut back without relocating
the emitter itself. It is always wise to place trees on a separate
valve.
New
plantings will require more frequent watering than mature or
established plantings.
The
average establishing period for new plantings is six months
to one year.
The
rates and times are based on a drip irrigation system with sized
emitter schedules per type of plant.
Let’s
say you have an average soil that perks well. Good percolation
is where soil is clear of any standing water within a few hours.
A general watering schedule will work well. Below is a general
watering schedules for most plant types, based on watering for
a period of one hour. This schedule allows for the best, healthy
looking plants.
Mature
native plantings, such as Mesquite, Paloverde, Creosote, and
brittle brush can go for extended periods between watering,
sometimes up to 100 days.
Without
knowing your soil types or conditions, I can only generalize
your watering needs. These guidelines are for basic, non‑native
plantings. Monitor your plants reactions for several days to
determine if this will meet your current needs.
If
this guideline seems too technical, here’s a simpler solution.
During spring and fall use 50 to 60% of your summer time
schedule. During winter
use 25 to 30% of your summertime use. Do not lower the time
increment, but rather reduce the number of watering days.
Craig
Allison has over 30 years of landscaping and nursery experience.
He previously held positions as a Faculty Associate at Arizona
State University’s School of Landscape Architecture and taught
design at the Desert Botanical Gardens in Phoenix. Craig has
over 50 published articles and has made appearances on ABC 15’s”Sonoran
Living Live” and on “Your Life A to Z” KTVK ch3. He currently
owns and manages Carefree Gardens, a retail nursery located
at the corner of Carefree Highway & Central Avenue in Desert
Hills and designs for New Garden Design and Landscape, Inc.
Call in or Listen to Craig Sunday mornings from 8 to 9 am Sunday
mornings starting May 21 on KFNX 1100 am talk radio.
If
you have landscape or garden questions you would like answered
email your questions to AskCraig@carefreegardens.net
or fax your questions to Carefree Gardens “ask Craig” at 623‑742‑7216.
Past articles can be found at www.carefreegardens.net.
