Many gardeners will use a variant of black plastic mulch on the soil combined with a soaker hose under the mulch when dealing with pepper plants and other heat loving plants. I’ve used this combination successfully for many years but I’m starting to notice certain plant stress signals that are leading me to believe that caring for peppers doesn’t stop once the plastic is on.
The benefits of the plastic mulch and soaker hose irrigation are clear. The mulch helps warm the soil faster in spring time, it prevents weed growth and it seals the soil off from the drying air keeping it moist so you don’t water as often. The soaker hose makes watering easy. You just connect one hose to your garden tap and let it drip for a good long time. In my case, only once every two weeks or so.
But within two weeks of planting this year I noticed some stress signs on my peppers. In the evening the pepper plants were appearing to wilt. The leaves curled, the offshoot stems drooped and the veins in the new leaves appeared to be more like a squiggle instead of a straight line. A quick search on the Internet revealed that they were likely suffering from some sort of environmental stress. After ruling out most diseases and temperature issues the most likely cause was watering.
Apparently peppers like being moist, but not wet. The way the soaker hose waters is somewhere in between. I plant my peppers according to Johnny’s Selected Seeds recommendation of two rows spaced 18” apart on the plastic. I place the peppers in the rows between 8” and 12” apart to try and create some shade as some varieties suffer from sun scald. This works well, except that the soaker hose has to be laid between the rows. I run it down one end and back up the other. With the planting hole and the stakes, the hose can’t get too close to the plants. Seeing as how the hose goes in before the plants there is a little guess work involved. After watering I noticed that the area around the hose is soaked but the outer edge of the plastic is completely dry. It is very hard to get a good watering.
What are the options? First, get yourself a good water meter. This is a little hand held device used to measure the degree of water in the soil. Great for potted plants. I measured right around my peppers at the planting hole and it measured about a 2 out of 10 just four inches down right at the edge of the planting hole. I thought that was too dry so I kept watering from the top in the hole everyday. However, on the other side of the planting hole the number was 4-5 out of 10. Probably too wet considering the black plastic doesn’t really let water escape.
You can consider next year winding your hose like a snake from left to right all the way down the plastic. This gives a better watering pattern but is very hard to bury in the dirt and if you have more than one plot it is prohibitive. It is also hard to find the exact location of the hose when planting and you probably sacrifice some preciseness in plant spacing. Or you’ll hit the hose with a hand shovel like I did.
The method that I will try next year will include drip irrigation from the top with small emitters. This is a tiny hose that lays on top of the plastic that you cut at the right length and add an emitter at the soil level of each plant. The advantage of doing this includes placing the water exactly where you need it and also provides the ability of adding a syphon through which you can feed a fertilizer solution. The disadvantage is that you need to be sure you will space your peppers correctly so that you can reuse the same hose next year. On the plus side, the hose isn’t very expensive.
Although the soaker hose method works well for some commercial growers, there may be another way if you are having trouble. Try adding an emitter style irrigation from the top this year and observe the results of your peppers. You may find it a good compliment or replacement to your soaker hose.