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Trees need water... but don’t overdo it!

Gardeners and landscapers have one thing in common with their “big brother” the farmer: complaining about the weather. Ask any farmer about rainfall and you’ll be told that it is nowhere near enough or it is way too much. Unlike Goldilocks’ third bowl of porridge at the three bears’ house, it is never “just right!”

At this time of year, we try to remind ourselves about the old adage that April showers bring May flowers... not to mention shrubs, bushes and trees. So with April finally behind us, we can assess whether or not our landscapes are actually getting the “just right” amount of water... for once.

Too much water can be as bad (or worse) than not enough water for your trees and shrubs. After all, if your soil is turning dusty from a dry spell, you can always turn to your trusty garden hose. But drying out waterlogged soil is a whole lot harder!

Here are a few quick watering tips for you to bear in mind...

When you’re watering trees, remember that much of the water will be absorbed by the roots at or beyond the drip line, not at the base of the trunk. The root system of a mature tree can spread out 1 to 3 times the width of the canopy, so that’s the most efficient area to give your trees a drink.

When it comes to newly planted or young trees that have yet to attain much of a canopy, water needs to be applied closer to the trunk area. New trees need more water than established trees. As the tree matures and the canopy spreads, widen the watering area. Once a tree is established, reduce the frequency of watering.

Best time to water: Early morning or evening, so that less of the water will evaporate in the midday sunshine. If you’re watering in the evening, avoid watering the foliage as this can promote the formation of mildew and fungus.

Don’t flood ‘em! If you pour on too much water too fast, you’re only adding to the problem. You can cause erosion and compact the soil, as well as wasting valuable water. Never apply water faster than it can be absorbed by the soil.

Allow the soil to dry somewhat between watering. This allows oxygen to be absorbed more easily. Use a soil probe or your own version consisting of a thin metal rod. If you can push the probe fairly easily into the soil but meet resistance at a depth of about 4 to 6 inches, it’s time to reapply the water. Bear in mind that this a rule of (green) thumb. If your nursery gave you specific watering instructions, be sure to follow those.

Applying a layer of mulch under the tree’s canopy will keep the soil cool and help to avoid evaporation. It will also keep you from mowing too close to the delicate roots and trunk where the whirling blades can wreak serious havoc!

You can more comprehensive information about watering trees at http://ag.arizona.edu/cochise/mg/wateringplants.htm and you can easily click on a link to that site when you find this column archived under the “Plant Man” heading at my Web site www.landsteward.org

Your specific needs can vary depending on your soil type, location and weather conditions. I’ll be happy to provide some personal advice on the kind of trees and shrubs that will work best for you and your landscape. Send me a few details at [email protected] and I’ll offer some ideas.

And now for a reader question...

QUESTION: “Last year I planted Red Sedum. What should I do this year to prepare the plant for this growing season.” – Louise Kraybill

ANSWER: To prep your sedum for the new growing season, cut back to the ground any old growth. Do not cut any new growth. At this time make a light application of organic fertilizer and then put down fresh mulch (up to 3 inches of organic compost is best) around, but not on the plants. Water until the soil is totally moist and water weekly during summer if there is little/no rainfall. This should get your plants off to a great start.

The Plant Man is here to help. Send your questions about trees, shrubs and landscaping to [email protected] and for resources and additional information, or to subscribe to Steve’s free e-mailed newsletter, visit www.landsteward.org