Winter Landscape Irrigation Tips

Home Grown  by Keith Reed
Now that winter has settled in, it’s easy to forget about our landscape until next spring. Or, at least it will be as soon as we get all our leaves under control! Note: We talked about leaf management a few weeks ago.

One task that should not be overlooked is the need to keep an eye on irrigation needs. When we talk about winter irrigation, the first question asked is always when and how much? That’s a difficult one as the answer is the one clients really don’t want to hear: it depends!

The answer is difficult because of our wildly fluctuating winter weather and high variability found in Oklahoma soils and landscapes. Here are some general tips that should help with the decision-making process.

  • If you have a mature, well established landscape, you may not need to do any supplemental watering, unless it is extremely dry. Last winter should serve as a standard for this. We were in drought conditions for most of the winter and had several significant cold snaps. If you suffered no landscape losses coming into this last spring, winter irrigation is probably not something you need to be concerned about.
  • If you did have plants that failed to make it through the winter of 2017-18, chances are they were either evergreens, plants marginally hardy to our zone (7) or newly planted. Plants that meet any of these parameters will tend to need supplemental water.
  • If your landscape does have plants that fall into the “might need water” category, unless we receive significant rainfall, it’s a good idea to go out and check the soil every few weeks for signs of soil moisture. The simplest way to do this is to simply brush aside the mulch. If it’s moist, conditions are ideal. If you don’t see any signs of moisture, investigate a little further by probing the soil several inches deep. I’ve found that a large screwdriver work great for a soil moisture probe. With a little practice, you can get a good feel for moisture levels by simply sticking it in the ground and judging the resistance required to push it in. Since every soil is different, you’ll probably need to dig a few small test holes or two to help you better access what differing moisture levels feel like. After a little practice, you’ll even be able to gauge moisture just by feeling the steel screwdriver shaft. Many people find this tip handy enough that it becomes their year around tool for gauging landscape water needs. It’s quick, easy, effective, and as handy as your nearest garden tool bucket.
  • When irrigating, apply enough water that the soil gets wet at least several inches deep. For large shrubs or trees, the goal should be to wet the soil 10 to 12” deep. A good slow soak is the best way to achieve this.

For more information on this or any other horticultural topic, you can contact Keith Reed, the Horticulturist in the Payne County Extension office. Keith can be reached via email at keith.reed@okstate.edu, phone at 405-747-8320, or in person at the Payne County Extension office, located at 315 W. 6th in Stillwater.

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