HomeMy WebLinkAboutM_The_Truth_About _Drought-Tolerant_ Plants_200323_v1Dan Gilchrist (/blog?author=59d56b97a8b2b0c031be0409) ·
June 4, 2018 (/blog/the-truth-about-drought-tolerant-plants)
Drought tolerant* or low water use* are terms we use often in
Northwest gardening. You see them on many of our plant signs
and information sheets at Swansons. More so each year, as we
recognize the importance of saving water in the face of our region's
growing population and potential effects of climate change.
Also, we see ever more examples of how beautiful a well-designed,
drought-tolerant garden can be!
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THE TRUTH ABOUT
"DROUGHT-
TOLERANT" PLANTS
[*Note: "drought-tolerant" plants can generally handle longer, dryer
conditions than plants labeled "low water use." But the boundary
between them is pretty thin (see definitions below). To simplify, we will
use the more common term "drought tolerant" to refer to both types
here.]
There are a lot of misconceptions about drought-tolerant plants —
what they are and how to properly plant and care for them.
Drought tolerant does not mean zero watering. If you are looking
for "stick 'em in the ground & forget 'em," sorry, we can't help
you much. Few plants will survive that strategy for long, unless
they are tapping into a water source other than the gardener. Most
of Swansons' signs actually say, "drought tolerant once
established." We also use the more inclusive term waterwise and
have a series of care sheets titled as such.
(images: Swansons)
THUS, THE UNEMBELLISHED TRUTH:
Drought tolerant does NOT mean ZERO watering!!! This comes with
two corollaries:
#1: Drought-tolerant plants need one to two (preferably two) growing
seasons of proper establishment, including regular, effective watering, to
make them truly tolerant of future drought periods.
#2: Most drought-tolerant plants will need some supplemental
watering during future extended drought periods, although generally
less than other plants which prefer more water.
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There are exceptions — plants which seem to thrive or survive for
years without any help. They somehow find water on their own.
But we should not expect nor count on those rare plant heroes.
Some popular drought-tolerant plants for the Puget Sound region
include lavender, rosemary, juniper, sedum, rockrose, sedum, and
yucca. Plants adapted to drier conditions have a variety of ways to
conserve water, including fuzzy or glossy leaves (which reduce
transpiration) or succulent tissue (which stores water). But our
concern in establishing them is their root system — best drought
tolerance for any plant is enabled when the roots grow deep so they
can find water when the upper soil zone dries out.
Of course, if we ever experience a prolonged, severe drought,
everything would need watering at some point. Our goal here is to
prepare them for more routine dry spells.
Even the drought-tolerant plants on New York City's High Line need
periodic watering. (image: Wikimedia Commons)
SOME DEFINITIONS
"Drought tolerant" — will survive extended periods without
additional water after being established with regular water and
fertilizer for two growing seasons. The plant may, however, look
marginal and neglected without some supplemental watering
during dry periods in later years.
"Low water use" — the plant will need periodic watering after
Low water use the plant will need periodic watering after
being established, but can be minimized with the careful
management of watering habits.
"Growing season" — spring-summer-fall. "Two growing seasons"
essentially means two calendar years not counting winters.
"Establishing a plant" — planting and caring for a plant (especially
the roots) to ensure that it can thrive with minimal intervention in
the future.
HOW TO ESTABLISH YOUR PLANTS
How do you "properly establish" a plant (drought tolerant or not),
and get those roots deep, for two growing seasons? Many of our
resources listed below explain watering techniques more fully, but
let's summarize their important points here:
• Prior to planting, prepare the soil to make it easier for the roots to
grow. Dig the hole 2 to 4 times the diameter of the rootball and 1
to 1.5 times as deep. Add up to 25% compost to the backfill mix,
especially if the native soil is compacted or hard to dig. This
increases both water-holding capacity and air spaces allowing the
roots to "breathe."
• For each and every plant in the ground, water the soil where the roots
actually are right now. This means water the small root ball when
the plant is new, or the diameter (at least) of the plant's branches
(the "dripline") on an older plant. This goes for either watering by
hand or irrigation system, which may need careful adjustment to
get the water to the right spots.
• Water to saturate the entire the root zone (width & depth). Make
sure the water penetrates through the upper layers of crusty or
powdery soil. Initially, it can be like trying to wet a dry sponge. It
may take some patience and ingenuity to get the water to soak in
rather than run off the top.
• Let it dry out a bit before watering it again. How long? It's hard to
specify, as there are many factors; it might be a couple of days to a
couple of weeks. Maybe every day during hot, dry weather. Best
thing is to check the soil moisture every few days at first. Roots
need a rhythm of water and oxygen. Too dry is not good —
constantly wet isn't much better. Too frequent, shallow watering
makes shallow roots, which may suffer during the next drought.
• Mulch the soil surface with compost or other organic material. This
reduces soil water loss, helps surface water infiltrate better and
bolsters soil health and fertility.
After a couple of growing seasons, you can gradually wean your
plants off the watering routine, but check them occasionally for
individual water needs, supplemental mulching, or other needs. By
the way, this is a good routine for establishing almost any kind of
plant.
Proper watering to help establish new plants. See a pattern here? (image:
Swansons)
Is it still worth it to plant drought tolerant plants if they need as
much pampering as other plants for the first two years? Absolutely!
They still require less water and general maintenance than
moisture-loving plants. We don't suggest purging your garden of
moisture lovers. We merely ask you to consider the areas where
drought tolerant plants can save you a lot of future watering and
work. Then take the extra steps to ensure that your plants get off to
a healthy start.
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Tagged: drought-tolerant plants (/blog/tag/drought-
tolerant+plants), Drought tolerant (/blog/tag/Drought+tolerant),
low water (/blog/tag/low+water), Plants for dry areas
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Watering tips (/blog/tag/Watering+tips), saving water
(/blog/tag/saving+water), Watering plants
(/blog/tag/Watering+plants), seattle gardens
(/blog/tag/seattle+gardens), pacific northwest gardening
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RESOURCES
Our website has a virtual flood of online and printed resources for
choosing, planting and caring for drought-tolerant plants:
Watering 101 (http://www.swansonsnursery.com/watering-101)
Best Watering Practices for Your Northwest Garden
(http://www.swansonsnursery.com/blog/2014/08/15/best-
watering-practices-for-your-northwest-garden?rq=watering)
Protecting Your Plants This Summer
(http://www.swansonsnursery.com/blog//protecting-your-plants-
this-summer-7-water-wise-tips?rq=watering)
Our Northwest Gardening Tips
(http://www.swansonsnursery.com/nw-gardening-tips/) page has a
whole section of care sheets on Waterwise Gardening.
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