Question of the Week – Number 3: August 27, 2020
“How often should I water my new plant, and for how long?”
The person asking the question said they had a new tree on drip irrigation, and they told me they ran the system every day for 20 minutes. They wondered if that was adequate. However, they didn’t include a photo or any background information.
Here’s why I told them I couldn’t answer.
I didn’t know the type of emitters they were using, so I didn’t know how many gallons of water those emitters would deliver per hour.
I didn’t know how many emitters they had hooked up per tree. In fact, I didn’t even know the size or type of tree.
They didn’t tell me the type of soil or where they lived. Conditions are quite different in sandy soils from clays and in Texarkana than in El Paso, just as examples.
I tried to compare watering plants to humans taking a drink of water. Our needs will vary a great deal. If we’re sedentary, sitting indoors watching a ballgame, we’re going to need a lot less water than if we’re outdoors mowing the lawn or playing ball with the kids.
My goal with newly transplanted trees and shrubs is to have a basin around each one so that I can fill that “reservoir” with water every 2-3 days during the hot days of mid-summer. I let it soak deeply into the soil, then I fill it a second time just to be sure they’ve been watered clear to the bottoms of their root balls.
I use a water wand with either a water breaker or, better yet, a water bubbler at the business end of the wand. That allows me to water at full or nearly full pressure.
I don’t water completely by clockwork, and I don’t meter out the amount, but that 2-3 day interval is fairly consistent for new trees and shrubs I plant out of 5- to 20-gallon pots, and I try to give each one of them about as much water as the size of the pot in which they were originally growing.
That means a 5-gallon shrub gets 5 gallons of water three times each week. A 20-gallon shade tree gets 20 gallons of water at the same frequency, but I’m quick to adjust it if those amounts or frequency don’t seem to fit.
Most people with drip irrigation systems, it seems to me, don’t run them long enough. If plants are lost in their first couple of years, it’s usually because they’ve been under-watered.
And, as for those water bags around tree trunks, a big “No thanks” from me. I very much prefer the way I’ve just described.
And finally, as for water meters to test soil for dryness, you have 10 of the best meters right there on the ends of your arms. Put them to use. Low-tech is best in this case!