Garden Column for the Salisbury Post
June 22, 2002
Darrell Blackwelder
I have to irrigate some of my plants every day just to keep them
alive, especially potted plants. I missed one hanging basket earlier this week and it was
completely dead the next day. I'm sure the drought is a problem for all of us now. This
extended drought is sure to be one for the record books.
I must sound like a broken record, but one must evaluate their water source before
committing to irrigate. If your water source is a private well, you need to determine if
it is it strong for constant irrigation. Unfortunately, vegetable crops require constant
irrigation. Many of the wells in Rowan County, especially older or shallow wells are now
at risk of running dry. Dr. Randy Gardner, tomato breeder with the North Carolina Research
Service, commented to a group of tomato producers at a field day last week that a healthy
tomato plant needs approximately 1.5 gallons of water per day to produce a normal crop. If
you have city water, can you afford the monthly bill? One has to be thinking also about
impending water restrictions in some areas.
At this point you have to ask yourself, what plants do I want to save.
Lawns are pretty much gone throughout the county. Fescue and fescue bluegrass blends have
all gone dormant and will remain this way until appreciable rain and cooler temperatures
returns. Grass will survive three weeks without any rain. If you're able water an inch
every three or four weeks just to keep the roots alive. The tops will still be brown but
the roots will survive.
Low pressure drip or trickle irrigation systems are excellent methods
of conserving water by metering water near the root systems of valuable landscape plant
materials. This system greatly reduces waste from evaporation and helps prevent foliar
diseases. Trickle irrigation systems meter water exactly from plant to plant, while weep
hoses are somewhat less reliable and should be avoided.
The ideal time to irrigate is in the early morning, avoiding
evaporation during the heat of the day. Avoid irrigating late in the afternoon or at
night. Night irrigation provides cooler temperatures without sunlight; ample opportunity
for foliar diseases to develop. Use a coffee can or similar vessel and a ruler as a
measuring device to measure the amount used if you use overhead irrigation. Shallow
irrigation is of no benefit causing more damage by to stress plants. Check the soil often
to make sure plants are receiving an adequate water supply. If you have a drip system,
place a small vessel beneath the hose to measure the amounts from drip emitters.
Automatic timers ease the task of irrigation and reduce waste by
eliminating over watering. Water timers meter water by gallons or by amount of irrigation
time desired by owner.
T here is really no way to tell a person how much to water a plant a
week. Plant species, soil types, exposures are only a few variables, which exist, that
confuse us. Newly planted shrubs and trees may need more water than well-established trees
and shrubs. Dogwoods, rhododendron, azaleas, and camellias have shallow root systems,
easily drying out in this type of weather and may need extra water.
Remember, do not over water these shrubs, as overwatering kills trees
and shrubs
much quicker than droughts. Hydrangeas wilt during the heat of the day, but become turgid
in the evening and early in the morning. Therefore, close examination early in the morning
is the best time to guage when to irrigate.
Mulching is one of the cheapist and most effective methods of water conservation. Three
inches of organic mulches such as bark or pine needles conserves a tremdous amounts of
soil moisture. Wheat straw, shredded newspaper, and other organic material should also be
used in vegetable gardens as an aid in conserving moisture, especially around tomato
plants and other plants that are heavy drinkers.
I've had many calls about trees dropping leaves due to the drought.
These are calls I usually get in August not in mid-June. Birch and silver maples seem to
be the worst at dropping leaves early. Premature leaf drop is nothing new for these trees,
but I'm not so sure about this year.
We've been lucky over the past few years as the droughts have been only seasonal. However,
our current situation is becoming extremely serious. Take time to strongly consider your
irrigation practices before using this precious resource.
Darrell Blackwelder is an agricultural agent in charge of
horticulture with the North Carolina Cooperative Extension
Service in Rowan County. For archived garden columns or other
information visit the Master Gardener Web site at
www.rowanmastergardener.com or email
darrell_blackwelder@ncsu.edu.