If you're a longtime reader of this column, you know at this time of year I almost always talk about watering, especially trees and lawns. This year is no exception. While we may not have any major concerns about water availability this year, higher water rates and the health of our plants make it important.

One of the major dilemmas that home gardeners face is determining what's enough, what's too little and what's too much water. While this may seem perplexing, it's as simple as checking the soil with a trowel or spade. I've often suggested a soil probe to make this easier. The probe takes out a core of soil when pushed into the ground and removed. If the soil is wet: it's too much. If the soil is dry: it's too little, and if the soil is moderately moist: it's just right.

How deep should the soil be? That depends on the plants you're watering. Most tree and shrub roots that are absorbing water are in the top 12 to 18 inches of soil. The effective rooting depth of the grass in your lawn is 6 to 8 inches. The rooting depth of other garden plants will vary, but an average depth is 10 to 12 inches.

Your goal should be to apply water to these depths only when needed. The frequency and amount you need to apply will vary with the type of soil, the weather and the amount of water your system applies. Timers have made the task of watering different areas of the lawn and landscape much easier, but they're typically misused. The "set it and forget it" method of watering each set 15 minutes a day (or twice a day) isn't good for plants. It provides shallow irrigation that wastes water and leads to grass and trees with shallow root systems, making them more vulnerable to drought and heat stress. Adjust your timer so more water is applied less frequently. Also, check the moisture in the soil and adjust your timer accordingly.

Drip irrigation is an excellent way to conserve irrigation water and is much more efficient (as much as 60 percent) than using sprinklers on trees, shrubs and garden plants. However, drip irrigation needs to be installed properly and managed with care. When installing drip on established trees and shrubs, note that the water-absorbing roots are not next to the trunk. The water should be applied at the dripline (the outer reach of the tree canopy) and beyond. A circular star pattern, starting at the drip line, of emitters works well for trees. Again, you can't simply "set it and forget it." You will still need to periodically check the soil in various parts of a plant's root system to make sure your drip is working well, that you have the right amount of emitters, and that the soil moisture is "just right."

Some other tips for watering "just right:"

-- Check your lawn thatch every spring. If it's greater than 1/2-inch thick, power rake to remove the thatch before the middle of April. Thick thatch impedes the penetration of water into the soil.

-- If lawn soil is compacted, aerate the area with a hollow-tined aerifier. This makes it easier for water to penetrate and move in the soil.

-- Deep-water established trees once a week during hot weather.

-- Mulch garden and landscape beds with a 3- to 4-inch layer of bark or well-rotted compost. Stay away from rock mulches, as they absorb heat and increase plant water needs.

-- Water slowly to avoid runoff.

-- When possible, water at night or early morning when there is less wind and temperatures are cooler.

-- Regularly check your sprinkler irrigation system for any problems such as leaks and broken or improperly functioning heads.

Irrigate properly to conserve water and maintain plant health. If Goldilocks can get it "just right," you can too.

* Marianne C. Ophardt is a horticulturist for the Washington State University Cooperative Extension Office in Benton County.