Overhead Watering: Should You Do It?

I have and use an over-head watering system in my gardens. And, according to almost any gardening article and book, that is not a wise thing to do. Okay, Mr. Master Gardener person why do you do it when the world says not to do it?

There is a concept called “rain.” I did not invent the concept, but it has been around for quite a while. Since, well, since a long time ago. The argument is that over-head watering is bad. That is a myth. The issue and problem regarding over-head watering is when you water your plants.

Folks tend to water when it is convenient for them, not when the plants need it. You work all day and watering your garden in a business suit or go-to-meetin’ clothes before you leave your home is not practical. So now you return home and change clothes and figure the time is convenient for you. Late afternoons can be very hot. Okay, maybe not this year so far, but last year we had a very hot and dry summer. So you get out the hose and spray the plants, remove the dust, and you figure you are done. Not so much.

It is better to water deeply, than lightly. If your soil is a sandy-loam mix, you may need to water more frequently. If your soil is a clay-loam mix, which is a bit more typical in Edina, you can water less frequently. Not sure what you have? When was the last time you had a soil test from the University of Minnesota? For a $17 bill they will tell you exactly what type of soil you have, along with what if any fertilizer you need.

Watering your container gardens at the end of the day can be okay. Containers, in general, need to be watered more frequently than your “regular” garden. Last year during the hottest days I watered twice a day—early morning and late afternoon or early evening. The water did not touch the leaves of the plant, but the soil surrounding the plants in the container. I typically leave about 2 inches from the soil line to the top of the container. I “flood” the container in those 2 inches, let it soak in, then repeat the process at least two more times or until the water is slow to soak in. I have about 40 containers, so yes that takes a little time, but it is an effective method. It eliminates any wastage through evaporation. Again, I am watering the soil. I am not spraying the plants, thus reducing any foliar disease issues. And by keeping space between the top of the container to the soil line, the soil remains in the container where it belongs rather than spilling out over the top onto your deck or patio.

My over-head watering system takes care of my regular vegetable and herb gardens. The system comes on at 03:15 in the morning and turns off at 05:30. The water pressure in Edina is fantastic most of the time and especially great in the early morning hours, before folks are up and about. Do not use over-head watering or any watering during the day, especially during the hottest part of the day. There will be too much evaporation and you will waste a lot of water. 

When you water early in the morning, the plants have time to dry out. This reduces any foliar problems and diseases, which is the primary complaint against over-head watering. Rain, which is an over-head watering process, can cause these diseases to occur especially if that day and subsequent days are rainy, overcast, and cooler than normal (read faux spring, 2013).

You can use a drip-irrigation system, which is very efficient and conserves water. You can also mulch your garden to keep the soil cooler while conserving moisture. If you water by hand (e.g., by hose), water the ground and don’t get the leaves wet. If you water using an over-head system, water early in the morning, before sunrise.

You cannot control when it rains. You can control when you water. Water when the plants need it, not when it is convenient for you to do so.