I’ve grown accustomed to soaker hose irrigation under black plastic mulch. The plastic mulch warms the soil and holds the moisture. The soaker irrigation hose makes that occasional watering so much easier. But there are some pitfalls with that snaky hidden hose - and you have to get it right in the Spring because you can’t uproot your plants and remove the mulch later.
Buy a quality soaker hose. Whether it is going under plastic, weaved through your perennial bed or on open ground a quality soaker irrigation hose will make your life easier. If you feel better about it get one with a warranty - my last hose was 7 years. I bought a cheap recycled brand for my first hoses and they dried out, became brittle and snapped! A good soaker hose will last if you treat it with care.
Unroll the soaker hose and lay it in the sun. A black hose in the sun becomes a little easier to work with as it heats up. Unroll it and smooth it out the best you can.
Test it BEFORE you put it under the plastic mulch. The soaker hose becomes a season long fixture once it is under the plastic mulch so it needs to be in perfect working order before you put it down. While it is still in the sunlight hook it up to your tap and run some water through it. Pick up the hose and walk along examining it for holes or uneven watering patterns. Some hoses have a greater concentration of holes in some areas which tend to reduce the pressure further down the line. If you used it in a previous season you may have a hole from a garden tool as well!
Repair any irregularities and holes. Some times you just have to make do. One of my hoses is only a year old and I already put it down for the season when I noticed a hole. I had to repair it in place so any method of repair will do! Roofing tar to seal the hole along with a piece of plastic from a margarine container and a hose clamp did the job. If your hose isn’t under warranty consider cutting out the section of damaged hose and replacing it with a piece of copper pipe plus the hose clamps. Epoxy is another good choice because it can be put on a wet leak.
Consider and plan your layout. I have chosen to run my hoses lengthwise in my beds because they aren’t all that flexible to run in a zig-zag pattern from side to side. Do what your plants need but think about it before you do it.
Lay the soaker hose under the soil. If you have a nice soil you can just use a hand spade or hoe to make a furrow to put the hose in. If your hose is tough to bend consider using galvanized ’U’ shaped hooks to hold the hose in place. This is the same thing they use to hold plastic row cover season extenders in place. Remember that black plastic must contact the soil for maximum effectiveness so you should use the back side of the rake or a leveling board to smooth the soil when you are done.
Leave some hose hanging out each end of the bed. You’ll need to hook up to a tap, and you may need to do some maintenance. These are the most likely failure points unless you hit it with a shovel! You’ll see why in a minute.
Test your soaker again. Before you lay down the plastic, hook the hose to the water supply and test it. This is your last chance to make changes.
Lay down the black plastic mulch. If all went well you can finish the plot. You should do this with an assistant on a sunny day because the plastic will stretch better, and as it cools it will contract to fit the soil nice and snugly.
Maintenance. You should flush out your hose as often as you need. At least once a month for me. That’s why we left the other end of the hose hanging out. You can remove the end cap and water (and rust, dirt, etc) will escape at the same rate it comes in. Invaluable.
Pressure. I find my hose has too much pressure and water tends to pool and run out (no thanks to my clay soil). I will turn on the tap full blast and wait a few seconds until the system pressurizes (I can hear it), then back off the tap until I get the right pressure. You can also buy a pressure regulator which will give you the perfect pressure for your hose (find it on the label).
Quick connect fittings. These little devices allow you to snap your garden hose to the soaker hose instead of twisting on the threaded end. I prefer these. Without them your soaker hose attachment sits open throat on the soil and gets a little dirt in every time you connect. This means more frequent clogging and flushing. Using the quick connect fittings eliminates that.
Working with soaker hoses under black plastic mulch certainly helps speed up your favorite plants while cutting back the time you need to spend weeding and watering. Once you’ve gotten a few soaker hose tips you are ready to put these invaluable tools to work in your landscape to minimize your labor and reap season long rewards.