How Should I Water My Plants?

Posted by

Two weeks ago, my topic for this column was that we need to be watering our plants due to the dry fall weather. Two things have happened since that article. First – It rained. We finally received a nice steady fall rain event. However, the precipitation totals varied throughout West-Central Illinois. In Monmouth this past weekend, that area only received 0.3 of an inch. Farther south, Perry, Illinois had over two inches of rain. Regardless, we're happy to get some much-needed precipitation.

The second thing that happened - I received some feedback about my previous article on watering. While my article stated you should be watering, a reader was curious on how should we water our plants.

Most homeowners' watering technique resembles what I see on TV or the movies. When it comes to Hollywood, often the person doing the watering is a nosy neighbor or the upstanding homeowner with the perfect yard. The culprits are usually hosing down the top of their hedge in the background of a scene. How do they get such a good yard when they water their plants so wrong?

Watering the leaves of a plant makes little sense. Plant leaves do not absorb water. Water uptake is the job of the root system. Additionally, continually wetting down a leaf surface often leads to foliar disease issues. Moral of the story: Do not water your garden like John or Jane Hollywood does on the big screen.

When watering trees, shrubs, perennials, or vegetables direct the hose to the soil. Most of us use a watering nozzle with different spray settings. I prefer to use the 'shower' setting the gives a broad, yet gentle pattern. Don't blast your soil with a sharp stream of water as that will lead to soil loss and splatter of soil onto your plant, which is another vector for plant disease. (Mulch helps reduce soil splash)

The primary question the reader asked was, "How long does it take to water each plant?" As with most things, the answer is "It depends." Primarily the duration of watering depends on how fast your nozzle delivers water. In college, professors had us calculate gallons per minute, based on water pressure, hose diameter, and hose length. That was in the classroom. Standing out the garden, hose in hand, trying to work a calculator, checking friction loss coefficients, and deciphering your shorthand stretches the chore of watering beyond cumbersome into absurd.

Outside of the classroom, we have the benefit of in-field trial and error. (AKA- make it work or your plants will die) Take your hose and a timer. Water the soil on one side of the plant for thirty seconds. Go to the other side and water for one minute. Dig through the mulch on both test sites. Is the soil beneath wet? Did the water wet more than just the surface of the soil? Use a hand trowel to dig or better yet your index finger to probe the ground. How far down did the water get? If you can feel moisture under the soil surface, you likely are applying enough water. Established plantings should be irrigated to a soil depth of six to eight inches. That equates to about one inch of rainfall or irrigation per week. Clayey or sandy soils, weather, mulch, plant density, etc. influence soil moisture levels and irrigation demand.

After experimenting with the timer, you may find that you have to stand at each plant for two minutes, or maybe even longer!

If like me you do not have the patience to hover over plants with a hose for an hour, consider drip irrigation. My vegetable garden is watered via a drip irrigation system, automated with an irrigation timer. In the past, drip irrigation was a foreboding term. Not anymore. Most garden centers now sell drip irrigation systems in kits, with all the parts and instruction you need. If you can hook a garden hose up to a spigot, you can install a drip irrigation system.

In my yard, trees and shrubs get watered with a hose set to a slow drip and placed near the base of the plant for an hour or two and moved about every twenty minutes. A five-gallon bucket with holes drilled in the bottom has the same effect.

Hopefully, this clears up the question of how should we be watering our landscape and garden plants. For more questions, you can always contact your local Extension office. Is that rain I spy in the forecast? Hooray! Time to put that hose down and let Mother Nature take back over.