Don't Buy Weedy Soil and Mulch!
I hate weeds. You hate weeds. So isn't it a kick in the pants when you discover the doofus responsible for all the new weeds in your yard is YOU? And it all started when you ordered that truckload of topsoil, manure, or mulch.
Such was the horrifying experience of two readers who recently emailed Grumpy. One had spread bulk topsoil over his yard, only to find himself the proud owner of a beautiful new patch of ground ivy. Another topped off her planting beds with bulk mulch and now boasts a superb collection of nutgrass.
The key word in both cases is "bulk" -- in other words, soil and mulch not delivered in bags, but scooped up into a truck from a landscape supply yard and dumped with great fanfare at the home of an excited and innocent gardener. Yes, bulk materials cost a lot less per cubic foot than bagged materials, but there's a trade-off. With bagged topsoil, manure, and mulch, you pretty much know what you're getting. Just read the label and stick to name brands.
However, with bulk material, you have to take somebody's word. Chances are, you'll get what you want. But you may also get what you don't want. So let's talk a little bit about how to safely buy bulk products.
Topsoil Topsoil and fill dirt are NOT the same. Topsoil is the rich, dark, pleasantly smelly layer of earth that typically covers the top 6-8 inches of undisturbed ground (unless you live in the Heartland, where topsoil goes down for many feet). The smell comes from a wealth of organic matter containing billions of healthy microbes that plants love. Fill dirt, on the other hand, has only one use -- filling holes. It's usually sterile, compacted, heavy clay that lies under the topsoil. It's good for growing nothing.
Here are three simple way to improve your chances of buying good bulk topsoil.
1. Buy from a local supplier you know. Ask where the topsoil comes from. Ask if it contains any organic matter. Ask if it has weeds.
2. Buy only screened topsoil that does not contain rocks, twigs, trash, or debris.
3. If you're suspicious, buy just a pot of topsoil, take it home, water it, and see if anything comes up.
Manure Cow, horse, and sheep manure start out as grass and other plants. The digestive systems of these animals allow seeds to pass right through in mint condition. So never use bulk manure that hasn't been properly composted for a year to kill the weeds.
Mulch As with topsoil, buy from a local supplier you know. Bulk mulch such as shredded hardwood and ground pine bark should have far less weed seeds than soil, because it didn't start out on the ground. So just inspect it to make sure it doesn't contain any leaves, stems, or vegetative matter. Make sure it's been composted for a year too, because fresh mulch will rob the soil of nitrogen as microbes break it down. DON'T buy mulch made from shredded pallets, pressure-treated lumber, or scrap wood. These could contain harmful chemicals or destructive insects, such as termites and borers.