Leave the leaves

What used to be a far-out, novel idea is now joining the mainstream: “Leave the leaves.” To support biodiversity and especially to provide protection for native insects, gardeners are changing our fall routine. For the past three years, I’ve been letting whole leaves lie on my garden beds.  

 

Whole leaves work as mulch

    This change allows me to do a lot less work. I used to spend many hours in late October and early November raking leaves to a spot at the back of the house where I could plug in my leaf shredder. I’d feed as many leaves as possible into the machine--basically a string trimmer in a drum—to make shredded leaf mulch for my perennials. 

 

Leaf shredder: effective but labor intensive

Now I just gather leaves from the driveway, the sidewalk, and the roadway along our block, rake them onto a tarp, and drag the tarp into the backyard. There I dump the leaves on whatever bed seems to need a blanket of mulch. 

    The concept behind this time-saving approach is that lots of native insects overwinter in fallen leaves, whether as eggs, larvae, nymphs, or adult insects. When I chop up leaves in the shredder, I’m chopping up those insects, reducing next year’s population of native insects in my yard. That’s working against myself, because I need a balanced population of leaf eaters, pollinators, and beneficial insects—the predators that keep leaf eaters in check—to keep my garden ecosystem healthy.

 

I want to host beneficials like this lacewing

 
    While environmentalists and proponents of sustainable gardening advocate for leaving the leaves, I’m disappointed to notice that some of my favorite garden writers are pushing back. I’ve read warnings that a cold-season mat of whole leaves will damage turf grass. Yes, we all knew that! Another worry is that perennials won’t thrive under a blanket of leaves. The thought is that plants from Mediterranean climates may need breathing room and a drier environment.

    All I can say is that these commentators must be gardening very differently than I do. Most of what used to be turf grass in our yard is now covered with wood chips that have no trouble accommodating a layer of fall leaves. And my perennials are ones that have proven tough enough to survive the conditions in the yard—sandy soil, rabbits, varying degrees of shade, humid summers with periods of drought and, increasingly, cold snaps in winter without snow cover for protection. If perennials needed pampering, they’ve long since died out in my garden.

 

Lavender toughs it out in the garden without special treatment

 
    Given my limited perennial-growing ambitions, I’ve had no trouble with leaving the leaves. Increasing numbers of birds visiting the yard suggest we’ve got more native insects than we used to.

    In spring I do like to peel back the matted leaves from the newest perennial bed off the back deck. It’s quick work to dump them in the wheelbarrow and move them to the compost piles. If I’ve got some dry fall leaves in bags in the garage, I’ll shred them at that time to replace the mulch I’m taking away. Moderation in all things.

Dwarf crested iris, another survivor

 
 

Taking stock

 It’s been a strange year in my garden. Dogs have completely changed the look and feel of the place. Now I’m about to leave for almost four weeks away, which means I’ll miss much of the fall flowers and foliage color. Before I go, it’s time to assess progress toward this year’s gardening goals.

 

I'm delighted to be growing spotted bee balm at last

 
    This was the year of fencing for my yard. I had to enclose new plantings in wire fencing to keep dogs from digging up the new plants. Older perennials also needed protection in spots the dogs targeted for digging (maybe places where they detected the scent or sound of chipmunks underground?). 

 

Using fencing to deter digging dogs

 

I laid fencing flat on top of the mulch and tacked it down with earth staples. Although I had some unpleasant surprises when the dogs overcame my defenses, over all the fencing worked pretty well. Unfenced areas are another story—lots of groundcover was lost to thundering dog feet.

    My most successful project was a new perennial bed planted into sheet composting. I’d let the mix of leaves and wood chips decompose for two years, helped along by some compost to introduce helpful soil organisms and blood meal to give the organisms a nitrogen boost. This year I reaped the benefits: black, rich soil for planting (mostly) native perennials that could thrive in part shade.

 

Echinacea, heuchera and penstemon getting established in the new bed

 
    Across from them I again planted cutting flowers inside an enclosure backed up against the rabbit fence that defends the vegetable and insectary beds. I chose tall dahlias that I could pick without opening the fence. Getting inside is awkward because the two small beds have no gates; the ends of the fencing are secured to metal posts with twists of wire. Since September, the dahlias have been producing lots of flowers for the flamboyant bouquets I’d envisioned. 

 

Enjoying flowers indoors

Zinnias and celosias in the same bed have been less productive, probably because they’re overshadowed by the towering dahlia foliage. Next year I’m going to try growing zinnias in pots on the deck, where they’ll get lots of sun.

    The beds around the deck haven’t filled in as fast as I hoped when I planted them four summers ago. They got too much shade. There’s still plenty of leaf mulch visible. In fall it’s gratifying to see expanding goldenrods covered with flowers and drawing attention from bees. 

Goldenrod-if you plant it, they will come

 

Asters in the next bed complete the pollinator buffet.

 

New England asters are great for pollinators too

    Around the garden pond I planted several pollinator plants in spring 2020, picturing bulky native perennials attracting crowds of native insects. So far that’s been mostly a bust. Only three species have survived. This year mountain mint (Pycnanthemum muticum) and wild bergamot (Monarda fistulosa) both sprawled inelegantly. 

 

Insects like mountain mint's odd green flowers

 

False aster (Boltonia asteroides), in contrast, shot straight up, producing one spindly stalk. Dry spells, lack of diligent watering, and frequent dog traffic are probably to blame for the others’ attrition. Next spring I’ll pinch the established plants frequently to keep them upright, fill the empty spots with more drought-tolerant selections—and protect the new plants with fencing.

 

A self-seeding volunteer aster is doing more for pollinators than any of my choices. Maybe native large leaf aster?

 

Ugly ducklings?

 Steve Aitken’s intriguing article about naturalistic gardens in the October issue of Fine Gardening reminded me that a garden inspired by native plant communities doesn’t have to look like a hodgepodge of plants. It often contains blocks or “drifts” of a single species or cultivar. Grouping them together heightens our enjoyment of the colors, textures and shapes of the chosen plants.

 

A drift of blue sage makes a bold statement-photo filipvandamme.be

    Now in late summer, I’m noticing some of those big aggregations in undesigned areas. At the edge of a mowed playing field in my neighborhood, large clumps have developed where one native species predominates, and they’re looking good. 

A big clump of Canadian goldenrod stands out

 

But these colonies were not intentionally planted. They’re weeds. This made me wonder: could some of the plants we think of as weeds be developed as reliable, easy-to-grow natives for garden use?

    Many weeds are nonnatives. But some that catch my eye do originate from eastern North America. There’s pale smartweed (Polygonum lapathifolium), with drooping chains of pink flowers at this time of year. 

Pendulous flowers of pale smartweed

The blooms offer nectar for visiting insects, and native caterpillars forage on the leaves. If pale smartweed’s flowers were twice as big and covered the plant densely, could you see growing a clump of this plant as a garden annual? The blooms aren’t too different from those of an amaranth I’m growing for cutting flowers.

Amaranth 'Red Garnet'

 
    I reflexively yank out yellow wood sorrel (Oxalis stricta), a native of both Europe and North America. It pops up all over the garden, and it’s easy to pull. But the yellow flowers are actually rather sweet-looking above fresh, tender clover-like foliage, and it blooms through the summer. 

Yellow wood sorrel is a familiar garden weed-photo Dcrjsr

Yellow wood sorrel is a pollinator plant, and birds eat its seeds. I could see intentionally growing a block of it and calling it an ornamental, especially if someone developed a variety with larger flowers.

    A lot of my lawn used to be taken over by common blue violets (Viola sororia), also native to eastern North America (now the lawn is taken over by wood chips). 

 

Violets took over where lawn used to grow

Violets like shade, and they do better in acid soil with low calcium content than lawn grasses do--but then, lawn grasses are such prima donnas! Violet seeds are surrounded by fatty elaiosomes that make them popular food for ants, birds and small mammals, and fritillary caterpillars eat violets’ leaves. 

With no work on my part, violets bloom in spring

I’m thinking of tearing out the last tufts of grass in one remaining lawn area and leaving the violets as a native groundcover. They can certainly deal with being walked on, and the flowers are pretty in spring.

    These are plants we see around us every day in New England. We know they’re strong growers that adapt to tough growing conditions. A lot of garden center darlings came into being because breeders recognized the potential of a modest wild flowering plant and made it more eye-catching through selective breeding. Breeders, have a look at our native weeds!

Woman-powered mowing

 After promising to pare down our lawn for at least ten years, I’ve now got its area down to about 200 square feet. This year’s big reduction didn’t happen because of any strong environmental commitment, though. It was all about accommodating a new family member, our young dog Lola.

Lots of wood chips and very little grass

    Since we installed gates between three yards to let Lola play with her neighbor dogs, prospects of a happy life for turf grass on our property have gone from dodgy to downright dismal. Thundering dog feet quickly tore away most of the existing lawn. Making the best of a bad situation, I covered the bare, muddy soil with a thick layer of arborist wood chips. What’s left is a few areas where the dogs move more slowly, next to the garden pond and along the vegetable garden fence.

 

This remaining strip doesn't merit a power mower

    With so little grass, I couldn’t see hiring someone to do the mowing. Instead, I’ve started a new chapter in my life as a lawn owner by buying a reel mower. I chose a Scotts model because it was cheap and lightweight. 

Easy to push

 

No one will ever mistake our patches of grass for a golf course, but so far the little mower seems to be doing the job well enough. If you look at the grass from the house, as we usually do, it looks mowed. It’s only up close that you see the uneven haircut I’ve produced.

    Until this year, I managed to get through life doing very little lawnmowing. When we moved into our house in 1985, my husband Steve took on the mowing job. He soon switched from a gas mower to a rechargeable electric model. I tried running it a few times and found it extremely heavy to drag around in the hot sun. No wonder so many young boys have hated this task! 

Our backyard in 1986, before we bought our first mower

 

When we expanded our yard and added more lawn, we hired a landscape contractor to do the mowing. That was the situation, with a recent switch to an organic practitioner, until this year.

 

The lawn in 2005 with unharmed perennial beds

 

    There’s a lot to be said for mowing with elbow grease rather than fossil fuels. In the United States alone, small gas engines running lawnmowers, string trimmers and leaf blowers emit 20 million tons of carbon dioxide every year, equivalent to about 4 million cars. 

 

Lawn perfection comes with a steep environmental price

 

Lawnmowers give off other chemicals too that contribute toward climate change and health risks: volatile organic compounds, hydrocarbons, nitrous oxides, and particulate matter. Just refilling those engines’ gas tanks, Americans spill more gas than the Exxon Valdez every year.

    Rechargeable electric mowers do the job more efficiently and generate much less pollution. But doing the mowing myself is even more climate friendly. It generates only the carbon cost of the very few calories I expend on the job.

    This is how I’m comforting myself for the scruffy look of the garden this year. By growing less lawn and pushing that little mower, I’m adding my tiny contribution to the effort to heal the climate.

Dogs eat leaves of Siberian bugloss (Brunnera macrophylla)

Rolling with the punches

With rainfall in Massachusetts staying about three inches below average for the year, gardeners are bracing for another summer drought. It’s worrying, but I’m impressed with how some of my established perennials are holding up.

A clematis is blooming well despite dry weather

    We often read that new plants need regular watering while they settle in. After the first season or two, they’ve established networks of roots and recruited fungal helpers (mycorrhizae) to collect water from the soil. When I started my garden, I wasn’t thinking about choosing drought tolerant plants. Now I try to avoid native perennials whose native habitat is described as a moist streamside. But some are more adaptable than you might expect. 

    Two areas of established plants look surprisingly lush despite the dry weather. Off the back deck, yarrow (Achillea ‘Coronation Gold’) is covered with flat yellow flowers. Nearby a bushy St. John’s wort (Hypericum ‘Universe’) is opening yellow blooms. A sneezeweed (Helenium ‘Short ‘n Sassy’) is coming into its own this year, putting out lots of foliage and numerous buds that promise an excellent display.

 

Bright yarrow blooms suit hot, dry weather

 

     In the insectary bed swamp milkweed (Asclepias incarnata) and ox-eye sunflower (Heliopsis helianthoides) are going great guns. This is an area of the fenced vegetable plot that I’ve devoted to planting for native insects. I call it an insectary bed instead of a pollinator garden, because it’s intended to benefit not just pollinators but also leaf-eaters and beneficial insects (the predators that keep the herbivores in check). 

    Swamp milkweed sounds like one of those moisture-lovers. Indeed, it grows naturally in wet meadows. But it’s doing fine for me in a rather dry situation. I like to think it’s providing larval food for migrating monarch butterflies. Another milkweed, butterfly weed (Asclepias tuberosa) is having a very good year in the same bed. That one took years to establish itself, but now it’s unfazed by the sparse rainfall. Common milkweed (Asclepias syriaca) is taking hold there too.

 

Swamp milkweed

    I’ve tried for years to grow common sunflowers (Helianthus annuus), but something always eats the seedlings before their stems get woody enough to support big flower heads. Ox-eye sunflower, which comes from a different genus, seems to have no problem coping with dry conditions. Instead of plate-sized sunflowers, I’ve got multiple yellow flowers attracting lots of insects.

 

Ox-eye sunflower attracts native insects

    I’ve been trying to establish some Joe Pye weed (Eutrochium spp.). These are billed as moisture lovers. One I planted last year had completely died back by the end of the summer after lackadaisical watering, and I wrote it off as a failure. This spring, though, it sent up new growth and seems to be thriving. I planted a group of Joe Pye weeds in a low-lying area where I hope they’ll benefit from water pooling when it rains. That’s a transitory event in our yard because our sandy soil drains rapidly. So far they’re bulking up surprisingly, considering that they’re regularly trampled by romping dogs.

 

Lavender and alyssum thrive in dry summer weather

    With dogs charging around the yard and rainfall infrequent, it’s nice to see some perennials rising to the challenge.

Gardening with dogs

Last fall we joined our yard to two others as a dog play area. We put gates in the fences that we share with our neighbors. Three of their dogs now join our hound Lola in sniffing, running, and tussling from early morning to after sundown. We’ve got some really happy dogs.

Lola surveys her domain

    With this open gate policy, Lola gets more exercise than I could ever give her and all the companionship she needs. For the garden, though, it’s been a big change.

    For one thing, that pesky lawn I used to complain about is pretty much gone. We might have a total of 200 square feet of turf grass left. All the rest has been worn away by running dog feet. I arranged for a load of wood chips to cover the bare ground where the lawn used to be.

Wood chips have replaced most of the lawn

    The lawn was relatively easy to lose. What hurts is seeing perennials shredded and shrub branches torn off by exuberant dogs. New paths have been cut through the borders where dogs charge through the plantings on their straightest line from A to B. They don’t care where I thought the paths should lie. 

 

New paths have appeared

    It’s worth it to let the dogs have their way with the garden, at least for a few years, for the sake of seeing them romping so happily. I’m hoping the destruction is something they’ll outgrow as they get older and more sedate. Then I can restore and replant.

    Meanwhile, I’ve had to make some choices about what to protect. I worried about it all winter, and in March I went outside to stake out the areas I’d defend for new plantings. Established plants can fend for themselves fairly well. Even decapitated perennials may grow back from their roots. 

 

Maybe this hosta will bounce back

But if the dogs dig up new plants and throw them out of their holes, they won’t have a chance.

    I started by enclosing a long, narrow bed in wire fencing supported by metal snow fence posts. This was the section I’d carved out from a patch of lawn and covered with sheet compost two years before. 

    It’s hard to drive those posts into our rocky soil, but once they’re in deep enough, they keep the fencing in place. I tacked down the bottom edge of the fencing with earth staples.

Earth staples from Gardener's Supply

I’d learned from last year’s experience that the dogs would nose their way under the fence if they could.  Last week I installed a new collection of native perennials inside this enclosure. Three carabiner-like hooks allow me to open the “gate”—a flap of fencing—to get inside if I have to.

 

Newly planted native perennials inside the fenced enclosure

 
    For the existing beds near the house, I took a different approach. Before the perennials started to emerge, I laid down fencing flat on the soil and pinned it down. My idea was that this would keep the dogs from digging. To add new plants, I cut openings in the wire.

Fencing tacked flat on the ground to protect bearberry

    So far these desperate measures are working, but determined dogs may foil me yet.

Protecting pollinators

There’s good and bad news about neonicotinoid pesticides during this spring’s plant shopping season. A Vanderbilt study that exposed honey bees to low doses of neonics found that after three days, the bees were sleeping half as long as normal. That’s bad news, because sleep-deprived bees have trouble finding their way back to the hive and may starve and die. 

Neonic-exposed sleep-deprived bees can't navigate

    Bees memorize visual cues for short flights, but when they’re farther from the hive, they navigate by using their circadian clock and their position in relation to the sun. Neonics disrupt bees’ circadian rhythms and throw off this navigation process.

    We seem to be accumulating more and more evidence that these pesticides harm pollinators, but the Environmental Protection Agency still hasn’t made up its mind to ban them or restrict their use, as the European Union has done. A ruling is due this year.

    As I made my plant shopping lists, I had to decide again whether to buy from my favorite garden centers. Could I trust them not to sell neonic-treated plants? I got some good news from two sources. A nearby farm stand with a large garden shop told me that most of their seedlings are started on site, and they don’t use neonics. They’ve switched to biological controls. This opens up a good source for common annuals I buy every year, such as lobelias, marigolds, alyssum, and coleus.

Pollinator-friendly marigolds and Mexican sunflowers, neonic-free

    Jack Russell, the owner of Russell’s Garden Center in nearby Wayland, called back in response to my inquiry about whether plant offerings at Russell’s are neonic-treated. I was relieved to hear his qualified no. Jack said their vegetable plants are neonic-free. For perennials and annuals, he said, they try not to sell anything treated with neonics. 

    The problem for Russell’s and other garden centers is the number of stops plants make on their way to market. Russell’s can certify that their suppliers aren’t using the insecticides, but they can’t be sure that seedlings or seeds weren’t treated before they got to those wholesale producers. Unfortunately, neonics persist for years in plant tissues.

Before planting, I want to be sure native moss phlox doesn't carry poisonous neonics

 
    Some of the suppliers whose plants I buy at places like Russell’s have made a strong commitment not to use neonics. Proven Winners, which produces many of my annuals, has vowed not to treat their plants, although they don’t quite admit that neonics harm bees. Most of the herbs offered at garden centers that I frequent are produced organically at Gilbertie’s Herb Gardens in Connecticut, so I know they’re neonic-free.

 
    In general, edible plants are less likely to be treated than ornamentals. Apparently sellers understand that consumers want pesticide-free food, but they’re slower to grasp how concerned we are about poisoning pollinators.

It's a relief to be able to source neonic-free annuals

    The good news is that the retail market is gradually catching up with ecological gardeners’ preferences regarding neonics. I’m delighted to be able to revisit my favorite plant shopping venues. Now if the EPA issues a ban, we’ll really feel sure that our gardens are safe for pollinators.

Alyssum that's safe for pollinators

 

Mulch reconsidered

 “Don’t mulch.” That was the surprising advice from native insect expert Heather Holm. What? That was a recommendation I’d never heard before. Heather’s webinar, “Attracting Bees and Beneficial Insects with Native Plants,” described the life cycles and needs of important native pollinators. Many build nests in the ground, she explained, and they need access to bare soil.

Tawny mining bee nest-photo Andrena Fulva 2d

 
    For years I’ve mulched my garden liberally. It started with an unsuccessful plan to use whole leaves to improve soil in the front yard. When they wouldn’t stay put, I invested in a leaf shredder that chopped the leaves into small pieces that didn’t blow around. Soon I was shredding all our fall leaves to spread on planting beds.

Shredded leaves make useful mulch

 
    I never had enough shredded leaves for everything I wanted to mulch, though, so I also brought in bark mulch from the garden center. In the last five years I’ve stopped using bark mulch and switched to arborist wood chips. 

     This idea came from Linda Chalker Scott, an author and urban horticulturist at the University of Washington who subjects conventional garden practices to objective scientific review. She compared different kinds of mulch head to head and found that the wood chips make superior mulch. They’re tops for holding water in the soil, modulating soil temperature, and suppressing weeds. They promote a health diverse population of soil organisms because they’re made up of a mix of different kinds of tree tissue.

 

Wood chip mulch is nice on paths and around trees and shrubs

    Wood chips fit in with my goal of reducing my garden’s carbon footprint by using locally sourced material. I get them from an arborist who works in the neighborhood.

    Now I’m re-examining my mulch approach because I want to help out native insects. What Heather advised against was bark mulch. She recommended shredded leaves, so I’m OK there. Apparently the insects don’t have a problem pushing their way through leaves to reach the soil, whereas a waxy crust of bark mulch foils them.

    Even better, Heather said, is a landscape where low-growing plants knit together on the garden floor. These plants perform the functions of mulch, and they can also provide food and shelter for native pollinators and beneficial insects (the carnivores that keep leaf-eaters in check).

 

Sweet woodruff has spread more than I'd like, but it does cover the garden floor

    Much of my garden is already provided with a groundcover layer. Two of the major players are sweet woodruff (Galium odoratum) and Canadian wild ginger (Asarum canadense). Between them they cover a lot of shady areas. There’s still not much growing under the shade of evergreens around the perimeter of the yard. This year I’m trying out native wild strawberry (Fragaria virginiana), which spreads by runners. I’m hoping it can survive and spread where other groundcovers haven’t. 

 

Wild strawberry, a native groundcover option

    Meanwhile, there are a lot more wood chips in the yard than ever before. They’ve taken the place of the lawn. Since we joined three adjoining yards to let our dogs play together, happy dogs racing around have worn away almost all the lawn grass. Instead of mud, we’re going with wood chips. I’m hoping the nesting insects will cope.

 

Lawn replaced with wood chips