by Julia Frisbie
posted June 3, 2021
Every year when my family asks me what I’d like for Mother’s Day, my answer is the same: to finish setting up this year’s drip irrigation system. By mid-May I begin to think ahead to summer drought, and I also get tired of hand watering all the transplants. Finishing the drip irrigation is a big task, but a fun one (we call it the adult equivalent of LEGOs) and it brings me great satisfaction.
By using drip irrigation, we:
- Waste less water by delivering it only where needed
- Cut down on weed pressure by reducing the surface area that gets wet
- Avoid fungal infections by keeping leaves dry
- Put it on “autopilot” when we travel, get sick, or get busy
If you’re worried you might forget or be unable to water, an automatic timer that can be programmed to run every morning is a good investment. Having your system on autopilot all the time isn’t optimal, but it’s better than NOT watering!
There are lots of good ways to set a drip irrigation system up. I’m going to explain my process step by step. Please know that it’s not the only “right” way.
First we bought a hose splitter, a backflow preventer, a pressure regulator, a timer, and a filter, and screwed them all together between the spigot and the adapter that connected it to the ½ distribution tubing:
That’s a lot of stuff! But it’s important for the usability, safety, and longevity of the system. Start up costs (both money and time) probably prevent a lot of people from installing drip irrigation. What’s worse, a lot of the supplies are plastic. In a class I took at Polyface Farms, another student asked Joel Salatin how he justifies the use of materials made from fossil fuels like plastic and gasoline. His answer was that for each situation, he asks himself: is there a less energy-intensive way to do this? That’s why he digs ponds to catch and store rainwater rather than relying on the aquifer, and places his ponds upslope of his fields so that gravity can move the water rather than a pump. But when it comes to actually delivering water to plants, he uses poly tubing, because it allows him to do more with less. He told our class, “there are virtuous and unvirtuous uses for everything. Drip irrigation seems like a virtuous use of plastic because it keeps us from wasting water.” Salatin’s not a perfect person, but I think his reasoning makes sense in this case.
- Following the instructions in Curtis Stone’s The Urban Farmer, we outlined each of our main annual beds with a closed loop of ½ inch distribution tubing:
- Then we ran two ¼ inch drip lines down the middle of each bed, attaching them on either end to the ½ inch distribution tubing. We inherited our drip lines from my grandfather, and they have an emitter every 12 inches. You can get lines with different spacing, or lines that are spongy like a soaker hose instead. That’s the backbone of the system. If you have a single garden area, it’s all you have to do! The couplers are easier to work if the tubing is warm, so I either do this on a hot sunny day, or I carry a thermos of hot water with me to soak the ends of the drip line in before I try to work with them.
- Because our garden tends toward complexity (a polite word for chaos), we also ran ¼ inch tubing from the ½ inch distribution lines to any areas outside the plot that we knew would need extra water. This allows us to place emitters at the base of perennials that are just getting established, and mini-sprinklers in our raised beds.
- At the end of each growing season, the ½ inch distribution tubing stays in place, but everything else is subject to change. If I need to temporarily remove ¼ inch tubing to prep a bed, I do so without a second thought, because it’s easy to put back. And on Mother’s Day each year, I double-check to make sure things are as they should be for the coming summer drought.
If you set a timer to operate your drip irrigation system automatically, I recommend setting it for as early in morning as you can stand to hear the water start running through the pipes. From Chan and Gill’s excellent book Better Vegetable Gardens the Chinese Way, page 67: “For as long as the Chinese vegetable growers can remember, they have always been getting up early in the morning to water their plants. They do not do this just because they like to, but because the way they understand the plants tells them that this is when the water is needed most.” They note that the plants need water to begin their day’s work of photosynthesis, and also that a blast of cold water can wash the leaves clean of bugs, and even of a light frost in early fall. (Your drip lines won’t be blasting any leaves with water, but that’s still good to remember for supplemental hand watering or fertigation.)
The first two years we gardened here, we were working with layers of cardboard, mulch, and arborist chips on top of sod. I knew it would take a lot of water to decompose that cardboard, and I knew that my plants would develop relatively shallow roots, so I set the system to water everything every morning. It allowed us to get good results even in marginal soil. I was thankful to put it on autopilot while we were distracted/exhausted by the birth of our son, and while I was busy nursing him and pulling wood chips out of his mouth.
As our soil has gotten deeper and richer in organic matter, it holds water better. For a few years, while our son toddled behind me and learned the names of our plants, I ran the system every other day or every third day. I supplemented the drip irrigation system by fertigating by hand with a diluted fish/kelp mixture by hand about once a week. I would always skip the drip irrigation for a day or two beforehand so that the plants would be ready to absorb as much as possible on “Stinky Fish Day” and get the maximum benefit. (“Stinky Fish Day” earned its name because I would absolutely reek by the time I came inside for breakfast, and be guaranteed time and space to take a shower by myself– a lovely side effect for any working parent.)
Last year, most parts of the garden only needed water once a week. After several years of rotational grazing by poultry, our soil’s fertility was through the roof, and I didn’t need to fertigate much other than dumping dirty duck water on my dahlias. So, I replaced “Stinky Fish Day” with “Drip Irrigation Day,” and only ran the system once a week. I did my spot watering by hand. (Spot watering is like spot cleaning for people who would rather do garden work than housework.)
How can I tell when to water? In the spring, when seeds are germinating and transplants are just getting established, I water almost every day that it doesn’t rain. In the summer, I usually garden barefoot, and although the top layer of mulch is dry to the touch, my feet can tell by its temperature and texture whether or not the soil beneath needs water. To double-check, I stick a finger in up to the second knuckle. If it’s dry that far down, I water. Some plants absorb a lot more water than others, so just because one area is dry doesn’t mean the whole garden needs a drink. It pays to walk every path every day and feel around. This year, we’re adding ball valves to our irrigation system so that I can toggle different areas on and off, pleasing both my thirsty cucumbers and my drought-tolerant tomatoes.
The great thing about a homemade drip irrigation system is that it can grow and change with you over time. When you’re starting out, it can be simple. As your soil (and your relationship with plants) becomes deeper and healthier, you can tweak it. Ecosystems get more complicated as they mature. Drip irrigation can support the emergence of complexity gradually and with grace.