The black death — aka landscape fabric — stifles your soil and looks lousy when it inevitably peeks through.
Sometimes I try to be fair and balanced on an issue so I don't sound like some kind of gardening zealot. Today isn't one of those times. I think landscape fabric sucks.
There, I said it. I regret using it in nearly every case that I have, and I try my hardest to show my clients why they shouldn't use it either. I'm not judging you if you want to try using the stuff — I understand why people want to. But after 17 years of designing and maintaining gardens professionally, it's a rare garden where I go "Oh yeah, that landscape fabric really worked out well!"
Here's why I hate it so:
1. It sucks the life out of your soil. Your soil is the happy home of billions and trillions of microorganisms which break down organic and mineral matter into usable nutrients for your plants to use for growth.
What's that mean in normal language? Your established shrubs and trees don't have to depend on you to fertilize them, because you've got this crazy army of micro-beasties making fertilizer out of your existing soil. How's that for a money saver?
I'm not a scientist, so I don't know the stats on it, but I can tell you what I have seen over and over again with my own eyes: After 10 years, you pull up the landscape fabric, and that soil is dead. Like — dead, dead.
Soil that started out cool, crumbly, loose — a soil that plants could stretch, wiggle their toes and relax into — becomes hard, dusty and impossible to dig with your hands. There's no organic matter left, water runs off the surface, and it's tough to dig new planting holes. I don't know what's going on under a microscope, but what you can see with your bare eyes is a big soil fail.
2. It kills the earthworms. Or at least it makes them go away. Earthworms like to do two things that are incompatible with landscape fabric: They like to eat compost, and they like to poke their heads out of the soil periodically to breathe and wriggle and do their earthwormy thing.
Earthworms rock because they keep your soil aerated with all their tunneling and wiggling, and their castings have all kinds of nutrients that help your plants grow. A soil without earthworms quickly becomes hard and sad.
3. The compost disappears surprisingly fast. In like three years, a substantial dose of compost or manure can break down and be used up by plants. The natural way is to have a slow, steady dose of compost making its way into the soil from the surface — either leaf litter or a layer of composty goodness or your wood chips slowly breaking down and adding organic matter to the soil.
This keeps the earthworms and soil microbes happily chomping away and creating free fertilizer for you, keeps the soil aerated and crumbly from all that happy earthworm wriggling, and keeps the soil cool and able to hold moisture.
4. Plant roots grow on top. Plants like to grow in happy mulchy stuff. You put happy mulchy stuff on top of your landscape fabric to hide it and keep it from degrading in the sunshine. Your plants send out roots on top of the fabric into the mulch, and then can't find their way into the soil because there's this crazy barrier blocking them.
This makes your plants less tolerant of drought and stress, makes them more dependent on you to water because their feeder roots aren't plugged into the damp depths of the soil, and makes it harder for them to extract nutrients from the soil because so many of their roots aren't actually in the soil.
This is even sadder when you rip up your landscape fabric in 10 years, which you will because by that time it will no longer be functioning as a weed barrier (stuff only lasts so long). You'll be inadvertently ripping out all kinds of plant roots entangled with the fabric.
5. The fabric is butt-ugly, and you will know this because a stiff wind will blow the mulch off. The landscape fabric will become exposed anyplace where you didn't smooth the soil below thoroughly enough, or where you have too steep a slope, or if there are whooshing ornamental grasses that brush back and forth against the ground in the wind.
Sprinting dogs, digging cats, kids and heavy rains can all expose your landscape fabric. And a black plasticky moonscape is exactly what we dream of when envisioning our ideal garden, riiight?
6. If you get behind on your weeding, it's a nightmare. So, it's supposed to cut down on your weeding time, right? And it sort of does, for the first year or so when the weeds in the top of your soil would have all been sprouting. Beyond that, you're weeding the same amount you would have otherwise, and if you get behind, watch out!
Once the weeds' roots get entangled in the fabric, it's very hard to remove them effectively. The weeds' roots firmly grip the threads in the landscape fabric so that all you can do is rip their tops off. Fun times.
In addition, you need to put wood mulch on top of the fabric to prevent the sun from degrading it, but wood mulch does break down into compost in time. That means in five years, you essentially have a layer of delicious growing medium on top of your fabric for weed roots to sprout in. What was the point of landscape fabric again?
7. It's a petroleum product. Yuck! I'm not some kind of "plastics must die" purist. Some of my favorite gardening tools have plastic handles or plastic parts. But if we can avoid supporting the petrochemical industry by saving ourselves labor and doing something great for our gardens, then that's just another benefit in the "no landscape fabric" checklist. I won't even get into what chemicals it might be releasing into the soil.
8. It's expensive and time-consuming to install. At about 50 cents per square foot, plus 12 cents a pin, those square feet add up fast. The installation rates about a two on the "damn it" scale — you'll probably only let fly with a couple of expletives while putting the stuff down. But it will take up your afternoon and make any future planting a "damn it"-worthy task in itself.
9. It limits your flexibility. You know how so much of gardening seems to be planting something and figuring if it doesn't do great you'll try it someplace else? Or shifting plants a couple feet to the right when they overgrow your pathway? It's a process of experimentation, at least for most of us.
And it's not an easy process with landscape fabric. Dig up, sweep soil off fabric, patch fabric, cut new hole, dig hole, plant new plant, sweep soil off fabric and smooth soil perfectly again, re-pin everything, move mulch back. Whew! I'm ready for a nap.
10. Goodbye love-in-a-mist, cerinthe, and surprise volunteers. Your reseeding annuals won't come up where there's landscape fabric, or if they do, they'll fail rather suddenly just before bloom because they can't get their roots into the soil. Like to do annuals or casually tuck in bulbs each fall? No planting decision is casual with landscape fabric down, and if you do cut a hole in the fabric for some bulbs, you better hope the gophers don't push them around. I've seen bulbs pushed a foot or two off the mark and try to come up from under the fabric. Very sad indeed.
So what's your alternative? Well, briefly, use a shedload of mulch! Good, weed-free wood chip mulch — a nice thick 3- to 4-inch layer of it — keeps any weed seeds on the soil surface from sprouting. It breaks down slowly, adding a little something to the soil as it goes, and you can always rake it to the side to plant or allow re-seeders to spread.
Genevieve Schmidt has written for Fine Gardening Magazine, Garden Design Magazine and other publications. She lives in Arcata, and owns Genevieve Schmidt Landscape Design and Fine Garden Maintenance. A version of this column appeared previously on her blog, northcoastgardening.com.