Saving more bees: How and why I'm rethinking mulch in my garden

For years I have been a member of the chorus of natural gardening advocates who tout the benefits of using mulch liberally to suppress weeds, maintain soil moisture, control disease by keeping dirt from splashing onto plant leaves, and keep soil-dwelling pests at bay.

Even better, I have said, is to put down layers and layers of newspapers to form a solid—but natural! decomposable!—barrier to really suppress the weeds for a full season or longer. 

Between the boxwoods: lots of mulch, and emerging crocuses

Then I learned about ground-nesting solitary bees. These gentle hardworking pollinators include several genera of wild bees, sometimes called digger bees or mining bees, and they need access to bare soil to excavate their nest tunnels. 

This 5-minute video from the University of Minnesota condenses an hour of effort by one such bee (genus Colletes), diligently working to move a couple of small wood chips out of her way and then digging a tunnel in a sheltered spot next to a rock. Imagine that bee laboring to move several wood chips out of the way and then encountering a thick barrier of newspapers—or worse, black plastic. Game over, little hapless bee.

The widespread use of mulch is a matter of real concern to bee advocates, like those at the UC Berkeley Urban Bee Lab, who call it "mulch madness"—and the use of black plastic weed barriers they dub BPI  for "black plastic insanity." (If you click on the link, you'll see a photo of a beautiful little green sweat bee,  genus Agapostemon, emerging from her underground nest.)

There's no reason to fear these gentle bees; they don't have a hive to protect, and it is very unlikely they will ever sting you. While the Cornell Department of Entomology says these bees will not sting unless handled, many species will even tolerate gentle handling, as the children of Sabin Elementary School in Portland, Oregon, will testify. Their playground is home to thousands of Andrena bees—the kids call them "tickle bees" and have adopted them as the school mascot.

A little patch of bare soil to the left—the beginning of a more bee-friendly garden

So what's a conscientious gardener to do?

Mulch less, mulch sparingly, mulch lightly—and don't replenish those bare spots that emerge as our old mulch breaks down or gets moved around. Plant groundcovers for living mulches that leave space for the bees. Get into the zen of pulling weeds once in a while. When we don't have the time or inclination to weed, we can focus on edging to give the perception of a neatly contained garden.  (Trust me on this—I have gotten compliments on a very weedy garden with tidy edges.)

And no more laying down of layers of newspapers—unless we want to shred them first, as researchers at the University of Ohio did to encourage ground-nesting squash bees, which they found to be more effective than honeybees at pollinating squash, pumpkins, gourds, and other related crops. They determined that a mulch of shredded newspapers and grass clippings was best at both keeping weeds down and supporting these valuable pollinators.

Other loose, lightweight mulches, such as leaves and the hulls of various types of nuts, are also good alternatives to wood chips and barriers. These are not only easy for the bees to work around, but they also get blown about by the wind, exposing a bit of soil here and there in the process, as found by the Xerces Society in their test fields in California.

Ground covers make attractive natural airy mulches. In one of my gardens, I planted periwinkle (Vinca minor) amongst the bulbs and perennials and a chokeberry (Aronia) shrub.  The periwinkle has spread and interwoven itself throughout the garden so that I really couldn't spread woodchips without burying it, so I stopped trying to mulch it, and have found that I only need to pull a few weeds from time to time.

Tulips emerging amid a very loose mulch of leaves, plant debris, and perwinkle

This garden is lightly mulched by happenstance with the leaves that fall on it, the debris from previous years' ferns, astilbe and other plants, and the periwinkle sprawling everywhere. I have come to appreciate the aesthetics of the variety of textures and shapes in this mix of light mulches and plants. And by mid June, the perennials hide most everything else anyway. 

Most importantly—for the bees especially—here and there, patches of bare soil have become exposed. And that's where I first noticed little bees hovering over the ground last spring, shortly after learning about them.

Another part of the same garden, with coral bells, emerging star of Bethlehem (Ornithogalum), more periwinkle, and a little bare soil, which you can see in the lower right 

I didn't plan it that way, but now I'll be looking to replicate that happy mix elsewhere in my yard.

Wrenifications

The wren first appeared in our backyard a couple of weeks ago, announcing his presence with what the Cornell Lab of Ornithology describes as a “rush-and-jumble song.” I was delighted to see him checking out the small bird house near the patio, then became alarmed when he headed over to the slightly larger one by the kitchen garden, because I thought the chickadees were still using it.

Wrens are known to be real estate hogs, stuffing many houses with twigs to form “dummy nests” so that other birds can’t use them; they sometimes go even further than that and actively eliminate the competiton. According to Cornell, wrens are sometimes the main reason for nest failure of bluebirds and chickadees, as well as some other species, which is why many birders don’t like them. So I was worried that the little fellow was going to do harm to the chickadee chicks.

I scurried over to shoo him away, saying, “You get away from there! That’s the chickadee house! You use the other house!”

“You’re talking to a bird,” said my husband from his seat on the patio.

The wren scuttled onto a perch in our neighbor Sue’s lilac bush, and I noticed that she had a bird house next to her garage also. Aha!  No wonder our yard is a magnet for the little speculator.

I didn’t hear any peeps coming from the chickadee house, so I decided to inspect it to see if the chicks were okay (a well-designed bird house will be easy to open so you can keep an eye on its inhabitants). What I found was a clearly abandoned nest. I then remembered seeing chickadees in the lilacs about a week ago, fluttering their wings like fledglings, but as they looked identical to the adults (not scruffy like robins) and I did not see them on the ground, I hadn’t put two and two together.

So I apologized to the wren, and he was soon happily stuffing twigs into both of our bird houses and, I suspect, Sue’s as well.

“In spring, the male establishes a small breeding territory by singing from exposed perches and putting stick foundations in prospective nest holes,” wrote Donald and Lillian Stokes in their Field Guide to Birds.

After several days of this, there was suddenly a noticeable absense of the wren’s musical bravado in the morning. Had his mate selected some other house down the block? If so, I was indeed sorry. They may be bad birds, but they’re voracious insectivores, and as a gardener first and bird watcher by extension, I would dearly love to have a family of wrens on pest patrol in my garden.

Then one morning I heard not only his by-now familiar burbling call, but a whole lot of chittering. I looked out the window to see two wrens engaged in a lively discussion as one perched on a nearby branch while the other went in and out of each of the houses.

It was fun to see this “songful tour of inspection,” as described by Christopher Leahy in The Birdwatcher’s Companion, after which the female chooses a nest and finishes it. And she’s a clever bird in setting up housekeeping, for she is known to stash a few spider egg sacs in the nest so that the spiders will devour any parasites that may infest the chicks, say the folks at Cornell.

I’m having a hard time telling which house she chose, as they appear to be dallying about both houses still. They are very active little birds, and the sexes look alike, so I find myself wondering if there is, indeed, only one female. According to Leahy, the name wren, which comes from the Anglo Saxons, has a traditional second meaning of one who is lascivious, possibly because of the polygamy of male wrens.

Rescuing the Peonies

Last June, before we actually closed on our purchase of this house, I stopped by with a handful of Popsicle sticks and a Sharpie to label the peonies along the south side of the then-empty house, noting  the color of their blossoms. I reasoned that by the time we moved in, their petals would have long since dropped and withered and I wouldn't know which were pink and which were white, and I thought I might want to dig them up and move them in the fall, with an eye to some to-be-determined color schematic.

But our house offered plenty of projects to keep us busy and I didn't get to the garden at all last summer. That's just as well, because it allowed me a full growing season to observe and photograph the garden. Among the things I observed was that nearly all the peonies were afflicted with splotches on the leaves and spots on the stems, most likely caused by one of several fungal diseases of peonies, especially if their spent stems and leaves are left to rot in place over winter. It also looked like some of the buds had failed to open at all.

Not remembering the blossoms themselves as anything special, only that some were white and some were a medium pink, I had pretty much decided they weren't going to be worth the bother and that I would just discard and destroy the plants and start over, planting new ones in a different location to avoid infecting them with the same problems.

Bloom of, possibly, Peony Annisquam

Then they bloomed, and I was smitten. As I hope you can see from the photos, the "white" ones are really a very pale pink, and their blossoms are so full of petals that even after dozens of the petals fell to the floor when I was rearranging them for the picture, they're still large and voluptuous flowers. And of course they smell wonderful, as do all peonies. A Google image search has me thinking these are probably Peony Annisquam, a 1951 introduction, and available from a Minnesota nursery, Hidden Springs Flower Farm. Since Julia Johnson had tended this garden from the 1950s on, and, from what I have learned from her children (who sold us the house) and our neighbors, was a pretty sophisticated gardener, it's likely she would have bought a few stylish new plants to enhance her yard. At today's prices, the several specimens that grow alongside the house would cost me $25 each to replace. I think I'll keep them.

Even the "ordinary" medium pink ones are, of course, beautiful and fragrant. How could I have thought I could so cavalierly discard them? Besides, ridding peonies of a disease such as this is pretty straightforward and amounts to nothing more than a few good cultural practices: adequate sun and water, good drainage, good air circulation, and—especially important in this case—a thorough cleanup of all plant debris in the fall.

Note the spots on the stem and browned edges of petals

Since I want to move them anyway, preferring a good swath of prairie next to the house (the reasons for which will be the subject of another post), I'll do so in September, a good month for dividing and planting peonies. When I do, I'll rinse the roots to remove the soil, which likely carries the spores of whatever is infecting them, and plant them in fresh soil amended with compost and manure. And as soon as the first frost zaps them, I'll cut all stems off at the soil surface and discard them and all the leaves (or, more likely, bury them at the bottom of a hugelkultur bed). I have treated similar peony problems this way before and did not have to do anything more, except to continue to remove the plant debris after frost.

Peonies are extremely long-lived perrennials, and I'm looking forward to many years (decades, really) of these luxurious flowers. It's also sweet to imagine that long after I'm gone, those peonies will still be here to delight future occupants of this house.