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Water, Water Everywhere

Water is the lifeblood of our gardens, and most gardeners regard it like liquid gold. It is also the most misused and misunderstood commodity in the garden.

Water is surrounded by myth in the Northwest. The first myth is that it rains a lot here. It does rain frequently, but it does not always rain abundantly. It may rain four to five days in a row here and produce less than 1⁄2" of actual rain. The second part of the myth is that it rains all the time. The truth is that we tend to have wet springs and falls but dry spells in both summer and winter. So our natural pattern is wet periods followed by periods of semi drought to drought.

Add in our denser soils and the influence of many large trees (the soil can stay dry in the tree's canopy, and the tree roots can suck up all the moisture in the root zone), and it is easy to see why many of our landscapes are in semi-drought conditions. In fact, the majority of winterkill in the Northwest can be attributed to drought stress, not cold itself (freezing can desiccate plants while inhibiting their ability to pull moisture from the ground, while cold dry winds suck moisture from everything they touch).

So what is a gardener to do? First, water wisely. This means thoroughly watering new plants in with long, slow soaks. It means watering established plantings infrequently and deeply. (Think of each plant and its root system as being in its own container. When you water, you want to try to "water the container"). And finally, it means checking to make sure that water is actually penetrating into the soil.

Second, water efficiently. This means adapting watering tools to watering situations. For spot watering (no bed ever dries out completely evenly) or for watering containers, a sturdy watering can, filled by hose or from a rain barrel, is often all you need. Or choose a good watering wand with a positive shut-off. Many now come with heads that have different spray patterns so you can adjust for different situations. If you are going to be dragging a hose around, you might want to invest in hose guides. These can cut down on the frustration of crushed or broken plants at the edges of borders.

For new plantings, especially trees and larger shrubs, treegators are an incredibly efficient way to water. (You've probably seen them used by the city on newly planted street trees.) These are bags that fit around the base of a new tree or shrub and deliver 10-20 gallons of water over a period of 1-2 weeks. Once trees are established most require little supplemental water. If they do, a deep root irrigator does an excellent job. This is a probe that puts water under the soil at the level of the roots.

Treegator Original	Treegator Jr, Pro

Large landscaped areas, vegetable gardens, or raised beds are best watered with soaker hoses or drip irrigation systems. Soaker hoses work best in situations where plants are arranged in rows, such as hedges or vegetable gardens. Soakers are limited in the area they can cover (about one foot on either side), and the amount of water they deliver can be inconsistent over the length of the hose. For this reason you should try to limit the length of soaker hoses to 25 feet per leg with no more than 75 feet running at once. Maximum length of a single hose is 50 feet.

A drip system is by far the most efficient way to deliver water to plant material. Drip irrigation can utilize soaker tubes, drip emitters, microsprays, and flood irrigators all in one system to irrigate a variety of plant materials. Drip systems utilize a central distribution line (usually 1⁄2" plastic) with sprinkling devices attached to it directly or with small 1⁄4" tubes called "spaghetti". Drip delivers water in small amounts over time directly to the root zone, so water can be better taken up by the plant with less waste. Drip systems are easy to design and set up, and they require minimal maintenance. They are also very easy to retrofit and adapt to the garden as it changes.

Finally, be consistent in your watering. Soakers and drip systems can be fitted with timers, so that areas can be watered automatically or when you are out of town. However, remember that things always change in the garden, so just because a system works now doesn't mean it will always meet your needs. And remember, as always, the staff at Sky is here to help with advice for your specific situation.

By Charlie Shull
Skylights Spring/Summer 2009, Vol 24, No. 2

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