Spray vs Drip irrigation
Updated: Jan 13
Clients tell me often, "Drip tubing is a pain. They get disconnected and geyser all over the place. Aren't sprinklers better and more efficient?"
No. Sprinklers spray out high and broadly and are best used in lawns that do well with that type of watering. Plants have roots around their base and need watering that is direct and efficient so a proper drip system is the best option for planting beds.
Drip systems are often installed incorrectly and then not well maintained, here's a good example:
If you walk around your neighborhood in the early morning, you've probably see this; broken drip tubing pouring out water. I came across this leak watering the wood of a birch tree. Not only is this major water waste, trees do not want the wood at their base watered because fungus will grow, which is one of the main causes of death in trees in our residential landscapes.
Ok, we see what's not right, let's understand what IS right by starting with some simple concepts.
In order to water efficiently with minimal to no water waste, how the water is delivered to the plant is important. There's two possible outputs; broad spray (from sprinklers on a high-flow valve) and emitters (from drip tubing on a low-flow valve):
When installed correctly, drip emitting line is the best choice for plants and sprinklers for lawns. What is wrong in the video isn't just the break in the line, it's that the install was wrong from the start. We don't want to stick emitters in a solid black feeder line, they aren't made for that. Let's forget about emitters because they are inefficient at watering around the roots of plants since they only drip in one place. The photo above shows emitting line that has built-in emitters every 6 or 12 inches, and that does a great job of watering plants.
This planting bed is watered with emitting line that is under the mulch layer and efficiently waters the roots of the plants.
When we broad spray plants, maybe only the foliage of the plant gets wet, but water doesn't get to the roots where it's needed. This is because plants often block the spray's throw, or the spray is too high above the plant or the soil is compacted around the plant so water just runs off.
Compacted soil happens in drought conditions and is a good reason to turn the soil so water can be absorbed (you see water running off on old lawns because the soil is compacted and can't absorb it).
Broad spraying planting beds also causes excessive weed growth, increasing garden maintenance costs and taking precious water away from the plant's roots where it's needed.
Below are sad looking gardens that are being water inefficiently with sprinklers. There's not many plants left because they have likely died. The water sprays overhead and doesn't make it to the roots of the plants:
This garden below has the best intention; using drought tolerant plants with a pebble mulch. Good idea? Not really, I'll get into why I don't like pebble as a mulch layer below, but they installed sprinklers which doesn't efficiently water the drought tolerant plants and wastes water by spraying the pebble.
I'm undecided about pebble as a mulch layer for a few reasons. One is that it gets very hot and emits heat. This heat can burn a plant's foliage and doesn't support the plants. Pebble mulch also doesn't support the soil beneath. A good natural mulch layer of ground wood preserves soil moisture so watering is reduced. Some people believe pebbles suppress weed growth, however not broad spraying a planting bed is the best way to reduce weed growth. There are wonderful ways to integrate pebbles into the landscaping, but maybe not as a mulch layer. Clients have also mentioned concerns that ground wood mulch is flammable. Not with a drip system below it that keeps it moist.
See the sprinkler watering this bed? There were probably more plants that died because of the inefficient, wasteful watering. Also, see all the weeds? That's from broad spraying the area.
I hope I have shed sunlight on the mystery of spray vs drip irrigation. Basically, we don't want to broad spray plants and emitting drip lines are the best option if installed correctly.
I hope you're enjoying the leaves changing colors and all the fall fruit that is available now.