Wednesday, August 25, 2010
Hay, You Get Out of My Yard!
Mulches are an important part of well-maintained gardens. Mulch does marvelous things: it moderates soil moisture and temperature; it can add an aesthetic value; it protects tender plants from frost and sun damage; it can add nutrients to the soil; and it can reduce the quantity of weeds. Of course it only reduces weeds if you use the correct mulch.
My experiment was to use a different mulch in each of my beds. I'd saved bags of leaves from last fall, so had crushed, dried leaves; I saved grass clippings from mowing and let them dry out a little; I had bushels of hay from the barn; and I had some straw. I know straw works pretty well so left it out of the experiment. In one bed I put leaves, another was hay, another was leaves topped with hay, another was hay topped with leaves, another was leaves topped with grass, another was grass, and for a control bed I didn't use any mulch.
It was very windy when I first started the process. Within two days most of the leaves in the leaves-only bed and the leaves-on-top bed had blown away; I replaced as much as I could. The hay and grass stayed pretty constant and the other combinations of grass and hay with leaves stayed in place best. Phase one showed that grass and hay does a pretty good job, but when you mix grass and leaves together it does very well at staying where you put it.
After watering and summer rains, phase two began. As expected, the grass and hay began to mat down and compress. It did a great job of keeping the soil moisture from evaporating, but it also hindered some of the water movement from above into the soil. The combination of grass and leaves seemed better, but also had some compacting in places.
Phase three was the most interesting and annoying aspect of the test. The grass and leaves bed had almost no weeds. The control bed had a few weeds, but nothing out of the ordinary. All of the beds with hay had weeds and the hay-only bed was the worst; it developed into very grassy growth. Multiple weedings helped, but the grass kept growing back. My conclusion is that typical ranch hay has millions of seeds and if you use it in your garden you'll introduce a new crop of hay.
Though relatively inexpensive as a mulch, hay has added hours of weeding to my normal gardening tasks. As the summer progressed, I occasionally added a new layer or two of lawn grass to a few beds and they're all doing great as far as weeds are concerned. The beds mulched with hay continue to produce green, grassy weeds.
Bottom line: don't use hay as a mulch unless you intentionally want to grow more hay. I've used newspapers and straw with great success. Though leaving grass clippings on your lawn is the best thing to do, occasionally bagging some for garden mulch can be very cost effective. Leaves are also cheap and make a great additive to grass.