Soaker hoses under black plastic mulch - an update

While getting the soaker hoses ready for the ground this year I made some observations that may be useful.

I performed my useful start of the year soaker hose maintenance, having missed cleaning up hoses before putting them away in the fall. I followed my tips article at Tips for soaker hose irrigation.

I laid out my hoses in the sunshine, connected them to the water supply and checked them for leaks. So far so good. I’m surprised at how much longer quality hoses last. Next I shut off the water and took off the end caps. To my surprise, something similar to algae had formed at that end of the hose. Almost as large as a tree leaf. I scooped it out and then turned the water on again to flush out any sediment that was in the line.

Some changes in recommendations I would make from my original tips article.

When using soaker hoses under black plastic or infrared transmitting (IRT) mulch, try leaving it above the soil instead of burying the hose in the soil. Last year I made the mistake of burying the hose too far away from the center of the plastic, toward the outside. Peppers, being a shallow rooted plant, and clay soil holding water, didn’t mix well. What I discovered was that the area around the hole in the plastic where the pepper was planted, would dry out really quickly, partly due to exposure to sun and wind, and partly due to the concentration of roots (and potting soil from the transplants) in that zone. When it came time to water my peppers, the soaker hose wasn’t close enough to reach the plants and depended on leaching water from the hose to the plant. The result was that the soil was sopping wet all season (peppers hate that) except for around the holes. I wound up watering by hand all season, every day, with a good soaker hose watering once a week. Had I placed the soaker host above the soil instead of burying it, the water would have spread out evenly across the top of the soil and then soaked in. So that is what I am trying this year.

I know, this violates the rules for using black plastic mulch. The plastic is supposed to be in contact with the soil tightly in order to have maximum effect. You can’t lay the hose on top of the soil and have the plastic contact the soil perfectly. It is a trade off, but one I’m willing to try. I attempted to push the soaker hose into the soil, just enough to lay flat, and I did it when the hose was a little warm and wet after sitting in the sun so it was pliable. Anyone who has tried to put plastic mulch down tightly on clay soil knows how hard it is. Bottom line is that is you try this, recognize it is a trade off.

In your own garden tests, try laying the soaker hose on the soil under plastic mulch, and another plot with it buried in the soil under plastic mulch and see which performs better for your soil type and plants.