University of Wyoming Extension
Horticultural Drought Tips
Hybner (Formerly with the UW Research and Extension Center, Sheridan) and Karen
Panter (UW Horticulture Specialist, Campus) put together the following
tips on water conservation as it applies to maintaining lawns. Water conservation
is sure to be a major issue this summer as we again face water shortages
across the state.
- Irrigation - clay soil holds water VERY well (almost too well) and
needs less frequent irrigation
- water early in the morning
- for automatic sprinkler systems, check them to make sure they are operating
properly - not watering the sidewalk and driveway for example
- thorough, deep waterings less frequently are better than frequent shallow
waterings - after watering, dig down to see if water has penetrated to
a depth of 6 to 8 inches - if so, you've watered sufficiently - if not,
additional time may be warranted
- check to see what the soil type is under the turf - sandy soil does not
retain water well and will need more frequent
- watch those "micro-climates" - around any structure there will be places
where turf will dry out quickly and areas where it will stay wet longer
- know where these are and tailor your irrigations accordingly
- bluegrass will require about 2 inches of water per week under warm, dry,
windy conditions - measure this by setting out a can or jar and then irrigate
as you normally would - after irrigating, check the level of water in the
container and this will tell you how much you're applying at each
- consider alternatives to bluegrass - buffalograss, some fescues, many types
of groundcovers, as well as ornamental grasses can be used
- mow high - 3 inches is recommended - this increases grass' tolerance to
drought and insect/disease problems
- when mowing, never remove more than 1/3 of the height of the blades at
any one time - if you want 3" tall grass, mow when the grass is no more
than about 4" tall
- make sure your lawn mower blade is sharp - tattered grass blades will lose
more water than clean cuts
- avoid overfertilization - this will lead to lush, soft, tender growth that
will not tolerate drought conditions wel
- core aerate each year - this helps keep root systems healthy.
- Heat Stress: Burned foliage on trees
and shrubs doesn't necessarily come only from lack of water. Often new
construction of light-colored fences and even the addition of aluminum
or vinyl siding on a house near trees and shrubs can cause serious damage
to existing plants. Alert consumers that any time changes are made in concrete
areas, decks, siding, fences, or even removal of nearby trees and shrubs,
existing plantings will be affected - usually for the worse.
The reason is that reflected heat and light from these additions cause
the side of the plant nearest the change to be warmer and to transpire
water more quickly than it did before. Unless the plants are protected
by a barrier of some sort, the plant simply will not be able to take up
enough water to compensate for the higher light and temperature load. And
so the leaves burn.
- Beware those Sunday newspaper ads:
Oftentimes Sunday papers will contain advertisements for plant materials
that may sound good on the surface, but will not tolerate our climate.
Recent calls have brought up this timely subject. The calls concerned an
ad for zoysia grass, touted as hardy to -30F, drought tolerant, heat tolerant,
easy to grow, and the greatest thing since sliced bread.
Unfortunately, the facts are not presented in the ad. Zoysia is a warm
season grass that is only hardy as far north as zone 6...it is highly recommended
for zones 6 through 10. We don't have any zone 6s in Wyoming. Zoysia is
adapted to the southern part of the U.S.
Ads such as this are placed nationwide, without regard to local climates.
We've seen ads like this for austrees, hydrangeas, and many types of fruit
trees - most of which are not recommended here. Remember, buyer beware,
and if the product looks too good to be true, it probably is!
- Brown Evergreens: We are seeing
a rash of winter drought and frost injury, mostly on evergreens. This winter
was a cold one and was preceded by a warm, dry summer and several warm,
dry winters. If property owners did not water trees properly in previous
years, count on seeing brown branch tips and possibly death of entire plants.
- More Brown Evergreens: Spruces and
firs seem to be dropping like flies. Basically, several warm, dry winters
followed by this year's cold, wet one have done evergreens in. Root systems
were weakened by drought conditions previous to this year. Then, the recent
cold winter was too much for some tree roots - many succumbed to the cold.
This translates to brown needles and branch dieback on the above-ground
portions of the tree.
- The Right Tree in the Right Place:
For understandable reasons, people love to bring trees (and heaven only
knows what else) from the mountains to their back yards. Aspens, spruces,
firs, and other plants are too frequently dug out of the wild (with proper
permits of course) and planted in urban areas. Unfortunately, this almost
always leads to problems. Spruces, firs, and aspens prefer moist, slightly
acidic soils and protected areas. Urban areas may be protected, but our
soils are usually not moist and are almost always alkaline instead of acidic.
Asking a tree to make the transition is a pretty tall order.
Think about where they grow in the mountains. Then think about the typical
Wyoming urban back yard. Hardly similar.
Add to that the fact that most people do not know how to dig a tree
properly, probably don't do much to protect the root system during transport,
and may not even have the site prepared at the tree's new home. Talk about
a stressed-out plant.
We recommend that people purchase trees from a reputable, local nursery
staffed with knowledgeable employees. Commercially-grown plants will have
been properly grown and cared for and will have a much better chance of
growing and thriving in the urban landscape.
- Use of Antitranspirants: The proper
use of antitranspirants has been a topic of interest lately. We recently
saw a sample of spruce (we think) that was so covered with the stuff that
it was sticky and the needles were glued together. No wonder the tree was
in poor health.
According to Richard Harris, James Clark, and Nelda Matheny, authors
of "Arboriculture: Integrated Management of Landscape Trees, Shrubs, and
"Sometimes leaves are stripped off or antitranspirant sprays are applied
to plants in leaf to reduce transpiration during and after moving. The
species sprayed and the concentration of antitranspirant applied must be
carefully chosen. Antitranspirants seem to be more toxic to evergreens
than to deciduous species. Used with caution, the sprays may reduce water
loss not only during the growing season but also during the winter for
conifers and other evergreens."
There are several types of antitranspirants:
There are drawbacks to each of these. The reflective materials leave a
colored coating on the plant that may not be aesthetically acceptable.
These also reduce light penetration into the leaf, reducing photosynthesis.
The spray emulsions reduce water loss, but they also reduce carbon dioxide
intake into the plant, thus reducing photosynthesis. The chemicals that
keep stomata from opening seem to allow more carbon dioxide in than water
vapor out, so seem promising.
some are reflective materials that reduce absorption of radiant energy
(heat), lowering leaf temperatures and reducing transpiration
some are emulsions of wax, latex, or plastics that dry on the foliage and
form thin films that minimize escape of water from the plant
some are chemicals that "affect the guard cells around stomatal pores and
prevent stomata from opening fully, thus decreasing the loss of water vapor
The authors suggest that "repeated application can retard growth by
seriously reducing photosynthesis. Even so, film-forming materials are
the most commonly used antitranspirants and have a place when reduced transpiration
for a few days to 2 weeks is crucial."
Antitranspirants are tools in helping plants endure stressful, short-term
periods. They are not panaceas or replacements for adequate watering of
plant material or proper plant selection.