Reining in water

Compared to the measly 1 inch of rain that fell on the North Carolina Arboretum in March, last month’s rainfall was a deluge! More than 6 inches saturated our corner of the Earth.

Although the rain brought an incredibly beautiful spring season, such fluctuations make it difficult to predict the weather even for the remainder of this gardening season, let alone for future ones. Consider, too, the rapid growth of our region and the increased demand this places on both private and municipal water supplies.

Will we get to the point where the availability of clean, fresh water, combined with changes in weather patterns, affects and influences landscape development and garden management?

It already has. Drought-stricken municipalities routinely place water restrictions on nonessential uses, including gardens and landscaping.

But even here in the mountains, we need not take our rain for granted. Instead, we need to rethink water use in our gardens and landscapes and start doing our part to conserve, protect and manage this limited and essential resource.

The term Xeriscape (meaning “dry landscape”) may be familiar to readers who’ve lived in areas where extended dry conditions are a way of life. Today, growing an irrigated fescue lawn in a Western desert region just doesn’t make sense. But back when lawns were seen as a status symbol, responsible water use simply wasn’t part of our vocabulary. It wasn’t until the early 1980s, when many parts of the West began experiencing serious drought conditions, that wasteful and consumptive water use was brought into sharper focus.

In Western North Carolina, where annual rainfall typically ranges from 48 inches in Asheville to 90 inches in the Cashiers/Highland area, Xeriscaping may seem ridiculous. But it’s not all cactus gardens and rock mulch: It’s really just a fancy name for good, basic gardening practices.

Whether you’re creating a new landscape or working with an existing one, begin as you would in any design process — by taking a good look around. How is the house oriented in relation to the sun? Which areas receive sun between noon and late afternoon? These will dry out faster than those in the shade and will thus require plants that can tolerate drier conditions, possible supplemental watering and more mulch.

Can you use trees, trellises or arbors to bring in more shade? Does the site tend to get a lot of wind? If so, use a windbreak or a mixed planting to slow down winds that dry out plants and soil.

Mulch is a must. I recommend using anything you can get your hands on: leaves, bark, paper, cardboard or any combination of them. Besides shading the soil, it reduces the competition by discouraging water-greedy weeds.

But when water does fall from the sky, do you know where it goes? Next time we get a real downpour, grab your umbrella and check it out. You’d be surprised how much potential there is in the concept of capture and reuse. The simple act of installing a rain barrel or creating a water garden can help put the water that falls now to very good use when and where it’s needed later.

Plant combinations of grasses, ground covers, perennials, trees and shrubs with similar growing requirements that are suited to the site. It’s better to incorporate trees in these beds than to stick them in the lawn, where they have to compete with the turf for water and nutrients. But don’t plant a bed of impatiens or other water-thirsty annuals around the base; go with a more companionable dry-shade-loving ground cover or mulch.

Soil preparation can never be overrated. A good mix of clay and organic matter (such as leaf mold or compost) will drain well in the heaviest of rains and still hold moisture during dry spells. Healthy, well-drained soils encourage strong root systems, helping plants become established and remain self-sufficient for years to come. But pampered plants that are fertilized with excessive amounts of nitrogen and given a lot of supplemental water may produce a lot of top growth that tends to droop at the slightest sign of heat.

Planting in the fall or early spring helps helps most plants get established before the heat of the summer arrives. But recent additions to your yard or garden may need extra water until they’re able to tolerate extended dry spells on their own. Perennials and small trees and shrubs may require supplemental watering for a year; larger trees may need help for the first two or three years.

Think irrigation. For newly planted ground-cover beds or annual vegetable beds, soaker hoses can help deliver water to the roots. Pay careful attention to these systems, however, since lines hidden under mulch can easily be cut and keep releasing water till the damage is discovered.

You may have noticed that I didn’t mention irrigating annual color beds; these should be greatly minimized or relegated to containers. If you are container-gardening, be sure to use polymer crystals that help retain moisture (most potting soils include them). A nearby water source eliminates water waste due to cut hoses or ill-fitting washers.

When it comes to monitoring how long and how much, a wand and shut-off valve at the lead end of the hose and a finger to stick in the soil make the best watering system. The wand puts the water right where it needs to go: at the base of the plant. The shut-off valve is helpful when moving from plant to plant. And the finger tells you exactly how deeply the water is penetrating.

If you need more hammock time, a slow-running hose (very slow) at the base of a tree provides the kind of slow soak those deep roots need. Automated irrigation systems are fine so long as a human remains involved; clocks and rain sensors aren’t much help in knowing when a plant needs water.

And then there’s the matter of turf. In common practice, it’s the ultimate resource guzzler and the greatest competitor for water, nutrients and light. But that’s only because we insist on keeping lawns lush and green for as long as possible.

Did you know that most grass types used in our area are cool-season varieties? This means they actively grow during spring and fall and go dormant in the summer and winter months. And when that happens, they slow down and even turn brown (horrors!) Yet many people are convinced that they need actively growing green grass even during the dog days of summer.

Learn to accept a not-so-perfect carpet of green. Let the grass flag a little and even turn a bit brown. Meanwhile, focus on practices like fall aeration and fertilizing, which encourage strong, healthy root growth. Better yet, reduce the amount of lawn you have by converting some of it to ground cover or shrub beds.

And whatever steps you’re prepared to take to use water in your garden more efficiently, start now. It’s really no different than turning off the water when you brush your teeth or shave. The plants will work with you, the weather gods will smile down on you, and future generations will be grateful that you did your bit to keep their drinking water clean.

[Alison Arnold is director of horticulture at The North Carolina Arboretum. She can be reached at 665-2492.]