Slugs, landscape fabric, and blossom-end rot, oh my!

OK, I admit it. I gave you a bum steer about slugs in my last column. I wrote that using beer as bait to kill the slimey, leaf-destroying creatures doesn’t work. Have you heard this theory? You’re supposed to put a shallow cup or saucer full of beer next to plants being ravaged by slugs so when they slide over for a taste (slugs supposedly love beer) they fall in and drown. End of slug problem. Well, it hasn’t worked for me. But several readers e-mailed to let me know the trap has worked just fine for them.

So I did some research on the subject and discovered two important things thanks to Jeff Gillman’s great book, “The Truth About Garden Remedies: What Works, What Doesn’t & Why.”

First, not all species of slugs are attracted to beer. Second, as Gillman so aptly puts it, “a poorly designed beer trap will attract a slug without actually trapping it.” Ah-ha! Turns out, I was setting my little dishes of beer on the ground, which meant the slugs probably couldn’t climb up the side to have a drink (and die, of course). If you want this to work, you have to make sure the lip of your cup or dish is even with the surface of the soil. Gillman also suggests that the beer be about an inch below the top of the cup so slugs have to lean out a bit to get it, ensuring that they’ll lose their balance and tumble in. (I know this sounds horrible. I go back and forth all the time on letting the poor things live and wanting to commit mass slug murder.)

In addition to their slug-trapping stories, readers have sent several gardening questions lately, so I’ll answer some of those here. One gardener asked about landscape fabric. Should she put some down before planting her new perennial garden? Heavens no. Though you see this stuff used by professional landscape companies all the time, landscape fabric (also known as weed barrier cloth) should never be used in an area where you want to plant living things.

Not only is it completely hideous (and some of it always winds up showing), it doesn’t allow water to penetrate the soil in the same way it would normally. It also prevents adequate oxygen from getting to plant roots where it’s needed. And just wait till the day you want to move a shrub or plant something new and you have to maneuver around that thick layer of yuck.

If you want healthy plants, skip the landscape fabric and use mulch instead. Shredded hardwood is always a good choice, and there are several sites in Minneapolis where you can get it for free. Check out this website for a location near you: Shredded leaves and cocoa bean mulch also work well, particularly around annuals and perennials. It sounds like overkill, but mulch should really be 3- to 5-inches thick if it’s going to help prevent weeds and retain soil moisture.

Several readers asked about how to care for their lawns during this seemingly unending drought we’re having. While we don’t have watering restrictions in Minneapolis, so you can technically water to your heart’s content, visions of staggeringly high water bills and an awareness of the impact of one’s own water usage on the planet tends to moderate how often we reach for the hose.

If you want your grass to be green and actually growing rather than holding its own, you’ll need to make sure it gets an inch to an inch and a half of water every week. As I’ve said in the past, you can easily figure out how much an inch is by putting out a rain gauge or an empty soup can or something before you turn the sprinkler on. You can get by with less water (a half inch a week or so) if you’re just looking to keep your grass alive. Grass is tough but it can get too brown and crispy to recover. Remember, you don’t have to do any extra watering if it rains enough to keep things happy.

Another reader asked why some of her tomatoes have big, nasty black spots on the bottom. This common malady is called blossom-end rot. It usually happens when tomatoes don’t get enough calcium. While there may be plenty of calcium in the soil, the tomatoes aren’t able to take it up the way they need to. Keeping your soil evenly and consistently moist will lessen the chance that this problem will happen again.

Thanks for your questions and happy gardening.

Meleah Maynard is a Master Gardener and freelance writer, living in Linden Hills. If you’ve got a gardening question you’d like her to address in her column, you can email it to [email protected]