I started setting up rain barrels to capture the water coming out of our downspouts several years ago, and have been adding new ones yearly. This year I decided to try out soaker hoses from MrDrip.com that are designed to work with rain barrels. I first got the idea from an article in August/September 2012 issue of Mother Earth News.
I have run loops around each of my 4′-wide raised beds, evenly splitting the lengths between the four rain barrels. The photo on the right is from the bed where I recently harvested the last of our potatoes and where bush beans are growing in the area harvested earlier. We’re now in drought conditions and have received less than a quarter inch of rain in the last seven weeks. While the soaker hose only appears to be watering about 4″ of soil, when I dug down 12″ I found that the soil was still moist enough to create a ball 12″ away from the soaker hose. And that’s the advantage of this method — it encourages deep root development of the plants.
When I first started using the soaker hoses, I was skeptical they were working. After a summer of use, I am coming to learn the pattern of how they work. The first 10-15 gallons of my 50 gallon drums are distributed by the soaker hoses in about 12 hours. It takes another 24 hours to move the next 10 gallons. The rate of flow continues to slow over the next week, but small amounts will continue to trickle out even a week after the barrels were last filled, and the soil 12″ down stays slightly moist. Occasionally I find that the flow stops prematurely, or doesn’t start once barrels are refilled. In those cases, I need to hookup a hose connected to the city water and push a little water through the soaker hoses to re-open the pores. I’m not fully sure why this is needed, but it was recommended by the support folks at Mr. Drip and has solved the only real problem I’ve had to date with these hoses. To simplify the task, I’ve attached to the end of my hose a ‘Y’ attachment with independent shutoffs for each branch. This way I can turn on the water at the house end of the hose, then go to the rain barrels and attach a couple of soaker hoses and turn the water on and off several times to each soaker hose with just enough pressure to get them running while I watch to make sure I’m not sending too much water and risking bursting those hoses.
The height of the barrels determines the rate of flow and how much water will eventually remain in the barrels. Things seem to stabilize once the water hits about 3′ above the top of the soil. For two of my barrels, that means they stop flowing at around 20 gallons left, while on the other two that takes them down to around 10 or 15 gallons.
Given this pattern of water flow and the effective soil water retention, I’ve gone to leaving the valves on my rain barrels open all the time. It takes about a quarter inch of rainfall to fill my barrels. When the rain is less than that, having the rain barrels partially empty allows for them to be refilled most or all of the way with little overflow, and combined the barrels and soil maximize the amount of water retained on the property and especially in the beds where the fruits and vegetables are growing.
Given the recent drought, I’ve had to start using city water to fill the barrels to keep the raised beds watered and the plants growing. But our overall use of city water for the gardens is down considerably as this method assures the water is placed directly at the root level of the fruit and vegetable plants. In the past, I used various sprinklers that not only watered the garden beds, but the pathways as well. Wind further blew the water away from the target fruit and vegetable beds, including onto the street. Water on the leaves of plants is more likely to evaporate before being absorbed by the plants. Further, while I would use a water timer to shutoff water to the sprinklers, I could never confidently determine how much water was actually feeding the soil because of all the variables listed. For a number of reasons, then, this soaker hose method, even when I need to resort to using city water, is far more efficient at providing a controlled amount of water to the specific target zones of growing fruits and vegetables.
Update 8/10/14: I didn’t take the soaker hoses in last winter but left them in place. They worked alright this spring, but as the summer has progressed I’ve had a hard time keeping them working in spite of flushing them out with city water periodically. While on this year’s Master Gardener’s garden walk, we visited a home that has been using standard, off-the-shelf soaker hoses with their rain barrels. I’ve been giving it a try and I’m finding it does indeed work. The flow is much greater, though, so I’m working to find the right level of open for the spigot to keep the water from running out in less than 24 hours. The experiments continue…