By: Sylvia McNeill © 2021 McNeill’s Tree Service
Living in an area of limited rainfall and still desiring to have some vegetative growth is often challenging. Whereas I do recommend planting reasonably for your area, making use of rain water is a great way to augment irrigation for landscape plants and trees. This may not allow a tropical aspect or thick English garden design, but it certainly may expand what is possible.
An inch of rain produces approximately .623 inches of water per square foot surface. Therefore, a 1000 sq ft roof can gather 623 gallons of water per inch of rain. That’s significant.
Two common terms used for rain water collection are harvesting and redirecting. Harvesting is where you collect the water in a container of some sort to be used later. Redirecting is literally directing it to an area to be used at that time.
Harvesting depends on the ability to set up receptacles in strategic areas and may be somewhat problematical on the size of the container vs the amount of rainfall. Being able to collect the rain water and use during dry spells, though, is wonderful if you can manage it.
The simplest method may be redirecting gutters. Instead of simply letting the water flow out of a gutter close to a house, additional piping can be added to channel that water to an area that can absorb the water for plant use. Every roof surface on our property has gutters that are redirected to planted areas. (Ok, full disclosure, my garden shed still needs its gutters but they are coming this year.)
The photo above shows the gutter coming off the east roof of the horse barn being piped into the center of this grove. They receive half of this roof as the other half goes to a mountain ash and blackberry patch on the north side of the barn. This grove was watered prior to installation of this gutter.
The grass areas are never watered, receiving natural precipitation only. When the rains dry up, so does the grass. It goes dormant and greens up upon receiving what nature allows.
The oak tree in the photo below received augmented water during establishment and dry spells. It was planted as a liner off site in 2010, moved here in late 2011 or early 2012. In 2016, it received its own dedicated gutter from the lower deck roofing on the east side of house (left side in photo). The upper house roof goes to honeylocust on the south side of the house. The full west side of the house (right in this photo) goes to the three ash trees.
As you can see in these photos, we use an abundance of mulch. It helps immensely if you have a mulched area around your plants as it will absorb and hold the water much longer than bare, mineral soil. As the mulch breaks down, it enhances the soil in many ways as well as adding plant available nutrients. We use whole tree chips. And, yes, that is easy for me to say since this is a by-product of our business. However, chances are there are companies in your area that supply whole tree chips for varying prices.
A side comment: We have received calls from people requesting chips saying they would “let us” dump chips at their place to save us money on dump fees. My suggestion would be to not start off the conversation in that manner as some areas don’t have to pay to dump chips. We don’t because there are already so many people who want them, we have never had to take chips to a landfill. Large companies in urban areas may well have to pay dump fees. Best to contact a company and simply ask what their policy is for delivering chips.
Back to water collection. Check out your state’s limitations on water harvesting, if any, to be sure you are compliant. Many states encourage this practice, but there are some states that have restrictions or limitations. These may range from how much water you can collect, to the use you make of it. Googling collecting rainwater will bring up websites with information on restrictions or conditions for the various states.