Irrigation 101

June has been a spectacularly disappointing month for me. Not because sales at my garden center were disappointing, not because the abundance of moisture we received; it was because I got sick with an ‘upper respiratory bug’ that took nearly the entire month to get over. This bug was one of the worst to hit me in my life.

So gardeners, if I provided bad information to you let me be the first to apologize as I am well again and clear of mind. So let’s visit about a subject most of Wyoming hasn’t had to deal with up to now—irrigating your landscape.

Mother Nature turned on the water spigot for May and June and just like a snap of her fingers, she turned it off. I want to take the approach of irrigating your landscape with the health of your plants first and foremost. But I also want you to conserve water and save you up to 20 percent on your water bill. Let’s go.

First things first, soil type matters and all gardeners’ soils are different. Some of you have sandy soil, others clay and the rest are in between. So what works for me in my sandy soil, doesn’t work for you if you have clay soils.

It has everything to do with water percolation into the soil. As you can imagine water easily percolates thru my sandy soil much faster than a gardener with tight clay soil. So what takes me twenty minutes to irrigate to a depth of twelve inches of soil depth may take the same gardener with clay an hour or more to get to the same depth.

Thinking along these lines, my sandy soils dries out faster and I must irrigate sooner than the gardener with clay soils has to.
So naturally I hate it when so called irrigation specialists set your irrigation system to come on every other day for 15 minutes. It makes no sense to me. It doesn’t reflect your soil type nor does it take into account plant health.

Understand this: almost all roots of plants live in the first twelve inches of the soil. Roots need oxygen as much as they need water in the soil to survive. As you can imagine as you go deeper into the soil, oxygen becomes the limiting factor. So irrigating past twelve inches is a waste of your water resource. Likewise, under irrigating forces roots closer to the surface where they dry out faster, creating an inefficient water wasting.

So if irrigating to twelve inches into the soil is the way to go, how does a gardener figure it out? The next time you plan to irrigate, time the irrigation. Afterwards, with shovel and a ruler in hand, dig up a portion of the soil and measure how far the water went into the soil. If it went only six inches, increase the time of the irrigation till the water penetrates to a depth of twelve inches, and record that time.

That time will never change, you’ll always irrigate for that time. What changes is the frequency of irrigating, when it’s cool out that frequency maybe every 10 days in May and September. In the middle of July with temperatures in the 90’s it might be twice a week. Even with my fast drying sand, I only need to irrigate twice a week.

All lawn fungal disease issues stem from poor irrigation practices— basically gardeners are irrigating too frequently, creating a ripe moist environment for the fungus to thrive.

By irrigating deeply and infrequently, the fungus issues go away, and your landscape plants will thrive.

Originally published in the Casper Star-Tribune, June 28, 2015