Georgia Gardener Newsletter Design Tip: June 14, 2007
Even with watering restrictions now down to a single irrigation day per week for some Georgians, it's still possible to have a nice garden and preserve
any plants you currently have in place. The article below briefly touches on the concepts of xeriscaping (dry gardening) but mainly
covers the pluses and minuses of the various forms of irrigation available.
Xeriscaping and Irrigation
As our local population increases, water availability is becoming an issue of great concern. While we usually have ample rainfall (not this year),
the storage capacity of our local reservoirs has not changed. Mandatory outdoor watering restrictions have been in place for several
years and these restrictions won't be eliminated any time soon. As a result, our landscapes often take it on the chin.
It stands to reason that if you want to have a nice looking landscape and conserve water, certain landscape changes are in order.
The term xeriscaping (dry landscaping) became part of our vocabulary several decades ago in the western states.
Faced with extreme droughts and often total watering bans, creative gardeners adapted. Loosely applied,
xeriscaping means using techniques and plants that do not need more water than is supplied by precipitation.
This varies from places like Phoenix, with less than 10 inches of annual rainfall, to Atlanta with an annual rainfall of 50-55 inches.
Creating a Xeriscape:
When it becomes necessary to irrigate your landscape, which methods are the most effective, timesaving and cost efficient?
This will depend upon the size of your landscape, the plants and the amount of time and money you wish to spend.
- Use locally native plants whenever possible. These plants have spent eons adapting to the local soil and climate.
There are also many suitable non-native plants from similar climates.
- Group plants together based on their water requirements. Place those needing the most water closest to a source of irrigation.
- Site plants based upon needed sun exposure and soil. Install the plants correctly by adding organic matter to the soil and monitor
them until they are established, which can take from 1-3 years, depending upon the species and size.
- Use a 2-3 inch layer of organic (not synthetic) mulch and replenish (not replace) it 1-2 times each year.
- Reduce or eliminate turf, especially thirsty turf like Fescue.
- Reduce fertilizer use during dry periods, especially those high in Nitrogen.
- Install a rain gauge and water deeply only when needed.
Without a doubt, this is a very convenient method of irrigation. You can set the timer and forget it.
Automatic sprinklers can cost thousands of dollars to install, especially if you have multiple zones and a large landscape.
There are drawbacks. Automatic sprinklers will run as set whether your landscape needs irrigation or not.
I've seen sprinklers running during a downpour. They also can be very inefficient, losing as much as 50% of the water to evaporation.
Many systems are also set incorrectly and water the landscape too frequently and for too short a time period leaving plants
susceptible to diseases and shallow, drought-prone roots. My advice is to turn the timer off and manually start the system
only when you need to water. The system should run only once or twice a week (if it's really dry) and only long enough to put
one inch of water on the landscape. Use a tuna fish or cat food can to determine the needed duration. Water in the early morning
to reduce water loss to evaporation.
Drip Irrigation Systems
Drip systems deliver water directly to the root zone of plants, either individually or in small groups. Like automatic sprinklers,
these can be set to timers. Above ground tubing is run through the landscape and each plant has its own head that connects to the main tube.
Usually all tubing is concealed below a layer of mulch. The amount of water delivered to each plant can be individually set based
upon the plant's needs. This is one of the most efficient irrigation systems since water is delivered directly to the plant and very
little evaporates. The drawbacks are that it can be expensive and time consuming to install. Somewhat complicated calculations are
needed to set the system for the correct amount of irrigation. If you make changes to your landscape (transplanting or installing
new plants), you have to change the irrigation system. Drip systems are not designed to irrigate turf areas and you have to remember
to turn the system off if there has been sufficient rainfall.
Soaker Hoses (Pictured Above)
I refer to soaker hoses as the poor man's drip irrigation system. I will say that this is my favorite system of irrigation.
Porous hoses are “snaked” through the landscape around the base of plants and covered with mulch. Water drips slowly from the hose
directly to the ground. Little is lost to evaporation. Soaker hoses are inexpensive and easy to install. If you make landscape changes,
simply reposition the hose. The drawbacks are that they must be attached to a spigot with a standard hose and are usually manually run
(although I've seen crafty gardeners devise timer systems). They are not designed to irrigate turf areas. You will also need to calculate
how long to run the hose to deliver the desired amount of water. Since they uniformly distribute water over the entire length, this is
where the practice of grouping plants together based upon water needs becomes important. Typically, a soaker hose will deliver 1 gallon of
water per foot per hour if you have average municipal water pressure.
Watering by hand is still a good way to make sure that the correct amount of water is given to each plant, but it's very time consuming.
Still some gardeners enjoy the task as it also gives them the chance to visually inspect plants and deal with potential problems early.
Once again, only water once or twice a week and in the early morning.
Gray and Rain Water Collecting
According to the state of Georgia administrative code, gray water is any wastewater produced in the home, including bathroom sink,
washing machine, and shower water, that has potential for nonpotable reuse. Gray water can not originate from a toilet or
kitchen sink. (Source: www.rivercenter.uga.edu).
While it's possible to utilize water from these sources (and I have done so in the past), it's an awful lot of work for a meager amount
of water. You may find that the water you save from these sources will have limited use for containers or small beds. I've had better success
using the water produced from the air conditioning unit being piped to beds where it's needed. This doesn't reguire extensive changes to
existing piping (as with washing machines) as the water is already being pumped into the landscape.
I have used rain barrels in my landscape for years. I have two 70-gallons barrels that receive water from downspouts that have been cut
to empty into the top of the barrel. If the barrels are placed up on a frame, access is easier for filling buckets and gravity will help
the water to travel through a hose.
Rain barrels can be a great way to save small amounts of water that can be used for containers or small beds.
Image Courtesy of Karen Alexander. Email for
Once again, 70 gallons doesn't go far, especially if the barrels are bone dry from lack of rain, but it can be the difference between life
and death for a small garden.
How Much Water?
Simply put, if your landscape receives an inch of water per week over the entire area (either by irrigation or rainfall) that's plenty for
most plants. For individual plants, four gallons per foot of height per week is usually sufficient.
Mandatory watering restrictions are in place and are always subject to change. Some counties and municipalities have stricter
rules. Currently, the state mandated restrictions are as follows:
There are some exemptions for farms, vegetable gardens, new landscapes and commercial operations. If you are unsure if you are subject
to tighter restrictions, call your water provider.
- Odd-numbered Addresses: Tuesdays, Thursdays and Sundays between midnight and 10 AM
- Even-numbered Addresses: Mondays, Wednesdays and Saturdays between midnight and 10 AM
- No outdoor watering on Fridays
Should we face even more harsh or total watering bans, you may have to make tough choices on what lives and dies in your landscape:
- Lawns and Annuals: Let them die. These are easily replaced and don't take long to mature.
- Perennials: These should be next on the list of things to let go. Many have the ability to go dormant in extreme conditions.
They are also easily replaced and mature quickly.
- Trees and Shrubs: Every effort should be made to save your trees and shrubs since they are the most expensive to replace and take
the longest to mature.
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