Perennial Notes Excerpts


These Perennial Search stories come from our archives. Horticulturist Jim Harrington installs and maintains landscapes throughout greater Atlanta. He is a past-president of GPPA. His conversation with editor Paula Refi was passed on in the Summer 2002 issue of Perennial Notes, and bears repeating for this and future summers of drought.

"Watering: A Word to the Wise"
By Jim Harrington

from Perennial Notes, Summer 2002

Perennial Notes: What, in your experience as a landscape professional, are the most common ways in which gardeners waste water?

Jim Harrington: Too many people are watering plants when they're not even showing signs of stress. I see gardens that look great, and the irrigation systems are running. Only a few plants, like hydrangeas, need regular watering. We need to educate people about which parts of the landscape actually require regular irrigation.

PN: Does this mean that you object to irrigation systems?

JH: No, they're just not something that you turn on and then forget. They should only be turned on when the plants show a need for water. I'd like to see a law requiring that all irrigation systems be equipped with a device that overrides the system if it's raining or the soil is wet.

The Georgia Department of Natural Resources website displays current outdoor watering restrictions.

PN: Is there a part of the landscape that has a higher requirement for water?

JH: Fescue grass in full sun. More water goes for that than anything else. My own Zoysia lawn was watered once so far this year. It's an established lawn, and I don't water it unless it needs it.

PN: What makes perennial plants better able to adapt to drought?

JH: Because they live longer, they have the ability to become more established with time. In this way, they're different from annuals, although certain annuals, if established well enough, are low-water plants, too. Whenever you plant anything, just make sure you have great soil.

PN: What actually happens to the plants when they are over-watered?

JH: When you over-water, the deeper profile of the soil is saturated. The deeper roots are deprived of oxygen, and they die. Then you're stuck with having to water all the time because the remaining roots are in the top few inches of the soil where they dry out faster.

PN: If we need to water, how should we do it?

JH: The water has to go down at least six inches. How you apply it depends on the plant. Drip irrigation works for new shrubs, but established shrubs shouldn't need this. Drip doesn't work in perennial gardens. I prefer to water by hand with an open hose because it delivers more water.

PN: What about watering wands and special low-pressure nozzles for hand watering?

JH: I think they deliver less water in the same amount of time and the plants end up not getting enough. I find there are very few people who enjoy watering after the first five minutes. The first plant gets a lot of water, then it tapers off, and the last plant doesn't get enough.

PN: How important is mulch?

JH: Always use lots of mulch. The plants don't care what kind, but some mulches work better than others in different applications. For example, bark nuggets don't work on a hill, and hardwood mulches isn't very good at controlling weeds.

PN: Do you use water retention granules?

JH: In every application I possibly can. It reduces the amount of water I need by 50 percent, and that's a conservative estimate. Grass, shrubs, vegetables, pots - you name it, I use it. It's worth its weight in gold. It isn't cheap, but I replace so few plants that it's worth it. It's less expensive if you buy it on the internet at It comes in three granule sizes. I don't use the smallest, but I like the medium granules for new sod and the course for everything else.

PN: What do you see happening to our gardens in the future?

JH: Well, people aren't going to stop building, and gardeners are the ones who will be cut off first when water is scarce. If we gardeners don't take the initiative to water properly, we're just not going to have enough water. As people who want to be able to garden, we need to make a statement.

The water restrictions we have now don't work. Instead of educating homeowners about how to water properly, they just forbid us to water. The people who are wasting the most water are the ones doing it while they sleep, not the little old lady who wants to hand water her pots and flower beds. She's being unfairly punished. If a total water ban comes, the landscapes with irrigation systems pumping all the time will be the first to bite the dust.

PN: Any parting thoughts?

JH: Only water when the plants show stress, and then apply to reach a depth of six inches. Don't over fertilize during droughts and pray for rain.