Post-pesticide paradise?

It’s been three years since I stopped authorizing pesticide spraying on our property. As this year's gardening season ends, I’m assessing the effects of that decision.

    After I pulled the plug, the garden wasn’t reduced to stubble by a plague of leaf-chewing insects. But neither did it remain unchanged. I'd sort of hoped that spraying all those years might have done so little that the garden wouldn’t look different without it.

Lush and green in 2013--but with pesticide spraying

    I started the spraying back in the 1990s when I noticed pinpoint white speckles on the leaves of Japanese pieris (Pieris japonica), an elegant early-blooming evergreen shrub. 

Marked leaves of Japanese pieris

A technician from Lueders Environmental diagnosed pieris lacebug, a tiny sap-sucking insect that originated in Japan and has spread around the gardening world. Decades of spraying kept the pieris leaves clean. When we stopped the spraying, the lacebugs came back. New foliage emerging the next spring was shiny and unmarked, but by the end of the growing season, all the pieris foliage was speckled again. 

    After we stopped spraying our many boxwoods (Buxus sempervirens) for psyllids, their leaves too weren’t as well formed and healthy-looking as they’d been with chemical protection. 

Psyllids have inscribed and curled these boxwood leaves

I’d thought the nonnative boxwood shrubs were problem-free. That was a false impression created by pesticide spraying.

    I’d agreed to use pesticides thinking I was protecting my trees and shrubs. Later we added dormant oil spray for hemlock woolly adelgid and Spinosad, a naturally derived insecticide, for winter moth. Those were nonnative insects with no local predators, I argued. I feared that they’d decimate my yard if they weren’t stopped.

A bleak scene: hemlocks dying from woolly adelgid infestation

    Around 2011 I started to get uncomfortable with this approach. Yes, I was targeting problem insects with each pesticide, and the chemicals had each been chosen for least toxicity for humans, mammals and birds. But my newfound concern for the native insects in the yard shifted the frame. I came to realize that no matter how carefully they were applied, these pesticides would always cause collateral damage, killing native insect bystanders that could be leaf-eaters, pollinators, or beneficial insect predators that I wanted to foster and encourage.
 

I didn't want to kill beneficial insects such as this ladybug, seen here eating an aphid

    After gradually cutting down on spraying, in 2016 I finally decided it was time to make a total break with garden pesticides. Regretfully, we had our hemlocks cut down so we wouldn’t need to spray for hemlock woolly adelgid, a particularly pernicious nonnative pest.

The fluffy white balls along these hemlock twigs are woolly adelgid egg cases

    Probably no one but me noticed when, without pesticide treatment, the leaf damage reappeared on the pieris and boxwood leaves. The leaves didn’t change color or drop off. The subtle damage just made me worry that worse was to come.

     Instead, this year the infestations seem less comprehensive. That could mean that without pesticides, the garden ecosystem is rebounding. In a healthy ecosystem, there’s a balance between leaf eaters and their predators. 

Dragonfly on St. John's wort: one of the predators I want to welcome

There’s also plenty of redundancy, so that if one population of insects has a hard year, there are others to fill their role in the community. I’d love to think that’s the ecosystem we’re building here.

Pillars of the community

With winter approaching, most flowers have disappeared from the garden. One family of flowering plants, though, keeps on giving. Asteraceae, the aster family, competes with the orchids for the most populous of all plant families. Flowers for pollinators aren't the only ecosystem services they offer. Lettuce, dandelions, thistles, dahlias, zinnias, and marigolds are all members of this vast tribe.

 

Black-eyed Susans are in the Aster family

    Most flowers in this family are daisy-shaped, from the tiny flowers of goldenrod to huge sunflowers. An older name for the family is Compositae, because each blossom is a composite of many smaller flowers. What looks like a petal of a daisy flowers is actually an individual ray flower. The central disc, where the seeds develop, can comprise thousands of tiny flowers.

 

The central disc of a daisy offers multiple flowers for pollinators to visit

     Walking around the garden this week, I could still spot the brown and black flower heads of asters (Symphyotrichum spp.), black-eyed Susans (Rudbeckia hirta), coneflowers (Echinacea purpurea) and oxeye sunflowers (Heliopsis helianthoides), all North American natives in the Aster family. Flowers of sneezeweed (Helenium autumnale), another cousin, were still bravely opening after a hard frost earlier in the week. I aim to have something blooming for foraging insects throughout the growing season, but this perennial’s performance exceeds expectations.

Sneezeweed flowers opening

    It’s good to have these Aster family members in the garden because they offer a lot to insects and birds. The Lady Bird Johnson Wildflower Center recently zeroed in on the contributions of sunflowers to Texas’ ecology. Sunflowers don’t just provide plentiful nectar and pollen for pollinators and beneficial insects. Extrafloral nectar exuded from stems attracts ants. Beetle larvae over-winter in sunflower stalks. Even wide sunflower heads benefit wildlife by providing cover for quail and grouse chicks learning to forage for food.

Sunflowers offer both food and shelter for native insects-photo Pudelek

    Sunflowers may still be blooming in Texas. Here the blooms are gone. Massachusetts has fewer native sunflower species, but in the cold months it’s easy to observe birds feeding off seeds of daisy-shaped flowers of Asteraceae. In my yard, they like oxeye sunflower seeds and the fat seed heads of coneflowers. I haven’t seen any goldfinches lately—they’re not frequenting my thistle (nyjer) seed feeder--but if some stop by this winter, I hope to see them perching on the coneflower heads I’ve left standing.

    Of course, the Aster family isn’t exclusively altruistic. I notice how good the flowers are at recruiting passersby to transport seed to new locations. A pappus, a hairy or bristly structure, surrounds each fruit and helps it attach to fur or clothing or be wafted by the wind. Picture a dandelion head that releases its seeds to the breeze.

It's easy to see how thistle seeds hitch rides

    I’m determined to grow some annual sunflowers to maturity one of these years. So far my seedlings have consistently been bitten off at soil level before their stems get woody. I blame squirrels. 

A futile attempt to protect a sunflower seedling

I have a “pest-control pop-up,” a 3-foot tall tent made of fine mesh fabric on a flexible frame, that I hope to deploy next spring. Maybe if I sow the seeds and cover the area with the well-anchored tent, I can foil the dastardly sprout-eaters. Hope springs eternal.

Compost shortage

Once my composting operation settled into a routine, I could count on having two of my four bins produce a good supply of fully made compost every year. Every fall I spread a thick layer on the vegetable bed, where organic matter is used up fast by food-producing annual plants. 

Food compost from the closed bin will enrich the soil of the vegetable bed

When I planted new areas, I spread compost on the soil surface before starting to dig. When I learned that harvesting (really mining) peat contributes to global warming by releasing carbon, I started mixing finished compost from the bins with coir (coconut fiber) to make homemade peat-free potting mix.

     This year I haven't produced as much compost as I used to, and I'm going through it faster. Last year I gave away so many potting mix samples that I ran short of finished compost. 

Cute, right?

The reason for the samples was to interest garden club members I met in making their own peat-free mix. I thought if they tried mine, they'd see how easy it is to make a mix that looks, feels and functions a lot like commercial products based on peat. 

     Last year too I piled fewer fall leaves into the bins. I used to heap up leaves on the bins at the end of the gardening season, knowing the fluffy mounds would flatten during the winter, gradually decompose, and become part of the compost. But last year I went big on piling the whole leaves on beds to provide winter shelter for native insects.

Collecting leaves from the sidewalk to pile on garden beds

     Another call on my compost supply last year was the sheet composting project I started last March. The majority of the material for this composting-in-place soil improvement mound came from thick layers of wood chips and fall leaves. Thinner layers of compost were needed, though, to introduce soil organisms that would do the decomposing. I can see that they're doing their work. Already this fall the mound has sunk to about half its original height.

The sheet composting mound is sinking and starting to look like soil

     These extra demands on my compost economy have left the bins nearly exhausted this fall. Cutting down vegetable plants and emptying summer containers, I've started the process again in two of the four bins. According to the old system, though, the other two bins should be full of year-old developing compost. They're not.

The cupboard is bare

     In the past, I've just waited two years for the compost to be finished. Usually I make a point of adding garden waste to the compost as it comes, with no recipe. But I don't want to go through next summer with no finished compost. I may have to adjust my lazy-woman's composting method this year. 

     To get back on track, I can mix shredded leaves with the dead plants in the bins. 

Shredded leaves will decompose faster

Combining "brown" high carbon and "green" high nitrogen components will speed up the process. Desperate times call for desperate measures.

New aesthetic needed

With October gone, the leaf blower season in my area is officially under way. Rain and heavy winds have brought down a lot of leaves, and many homeowners feel those leaves need to be disposed of post-haste. That means blowing or raking every last leaf into a pile and stuffing it into a leaf bag or vacuuming it into a truck to be transported to “away,” wherever that is.

Move 'em up and move 'em out

    Two years ago some local citizens rose up to protest the noise and health risks caused by leaf blowers. Some towns around the country have imposed meaningful limits, and some have even succeeded in passing outright leaf blower bans. But here, the team I was backing lost the fight, or at least the first round. We ended up with a complicated new noise ordinance that still allows leaf blowers seven days per week, with gas models permitted before Memorial Day and after Labor Day. 

After Labor Day, gas-powered leafblowers are free to roar in my neighborhood

I think this means the anti-leaf blower faction underestimated the determination of local landscape contractors to defend their business model. Leaf blower noise continues at a cost to the rest of us: loss of quiet enjoyment of our property. I hope we’ll eventually achieve an ordinance with more teeth.

    If I ran the zoo, we wouldn’t need leaf blowers because we wouldn’t clear fallen leaves from our yards. My town, like many, is stuck with a standard of landscape maintenance that dates to the aftermath of World War II. According to this aesthetic, fallen leaves are whisked out of sight as quickly as possible, and an ideal front yard consists of a swath of neatly mown lawn, as big as possible, backed by a few shrubs planted against the house’s foundation.

Neatness reigns

    As I’ve traveled farther along the path to a sustainable garden, I’ve gotten increasingly comfortable with seeing leaves on the ground. Fallen leaves on garden beds used to look like a mess to me. Now they’re a pleasing part of the view, just the way they’d be on a walk in the woods.

Fallen leaves enhance the beauty of the woods

    I’ve learned there are lots of good reasons to let those leaves lie on the ground. They add organic material to the soil as they slowly decompose, providing nutrients for plants and improving soil structure. They offer shelter for native insects, helping them survive the winter. They act as mulch, minimizing the number of weeds I’ll be coping with the next spring, insulating the soil so a sudden thaw or cold snap doesn’t kill my plants, and helping to hold moisture in the soil for roots to access.

Fallen leaves and pine needles benefit this shady bed

    Now I wonder why my neighbors bother to send away all that valuable organic material and then pay to replace it with mulch or soil amendments. If we send those leaves away, we’re actually depleting our own soil, because what our trees drew from the soil isn’t replenished by decomposing leaves.

Why send away organic material that should become part of your soil?

    But the truth is, I wouldn’t be letting those leaves lie if I hadn’t come to find them pretty. In garden design, neater isn’t always better.

Big little choices

The other day I found myself dithering about covering our garden pond with netting. I hadn’t realized how much transitioning toward sustainable gardening has changed my thinking process.

This week in the garden

    Every fall I drag a lightweight frame made from plastic pipe and covered with bird netting over the 8- by 10-foot rectangular pond. The purpose of the pond cover is to minimize the number of falling leaves that end up in the water. 

The gray plastic pipe holds netting over the pond surface to keep out leaves

If leaves spend the winter on the bottom of the pond, their gradual decomposition will suck the oxygen out of the water, creating tough conditions for any animals living there. We don’t have koi anymore, but I buy five or ten tadpoles at the garden center each spring and enjoy their emergence as tiny froglets.

Tadpoles metamorphose in the course of the summer-photo Olaf Tausch

Adult frogs eat insects. I count them as part of my garden community.

I managed to photograph this frog from a distance before he jumped into the water

     My dilemma this fall was twofold. First, should I try to skim the floating duckweed off the surface of the pond before winter for aesthetic reasons? What if tadpoles were still depending on duckweed for food? What if I skimmed off frog egg masses with the duckweed? If I’d asked to know the scientific name of my tadpoles, I’d be more equipped to find answers to these questions. After a few passes with the net, I decided to leave the duckweed alone.

Duckweed on the pond surface provides high-protein tadpole food, prevents algae build-up by shading the water, and controls mosquito reproduction

    Second, if I covered the pond completely with the netting frame, how were those frogs going to get out of the water? I’d lowered the pots of water lilies to the bottom of the pond, so there were no lily pads on or near the surface where they could perch. The weather hasn’t gotten cold yet, so I didn’t think the frogs would be ready to go into their winter hibernation. Several small frogs are in the habit of sitting at the edge of the pond and swiftly jumping into the water if anyone approaches. I compromised by leaving a 1-foot opening where the pond was uncovered next to the frogs’ favorite sitting area.

Space for frogs to escape from the netting-covered pond

    Ruminating about the needs of frogs made me realize that my perspective has changed a lot in the last eight years. In shifting to seeing myself as part of a community of living things in the yard, I’ve opened up a lot of questions that never would have crossed my mind before. 

    How about this one: should I throw the cones dropped by our big white pine into the yard waste?

Pine cones: yard waste or winter forage?

I’ve done that for years, because I didn’t want the garden to turn into a white pine forest. This year for the first time I hesitated. Maybe those cones feed some animal during the winter. I compromised: I threw the cones lying on paths and lawn back toward the base of the tree.

My compromise is to move the cones back within the dripline of the pine

    Will I gradually stop being able to do anything in the yard except remove nonnative invasive plants? No, I insist on retaining the right to be a gardener! But I’m seeing a lot of my choices differently.

Climate action in the garden

It’s been a discouraging month of environmental news. The UN climate summit confirmed that there’s not a lot of time left for international action to prevent catastrophic climate change, but national governments, notably ours, are not making adequate commitments. 

Unlike polar bears, we humans do have the power to combat climate change-photo Gerard van der Leun

A group of ornithological organizations published a study estimating that we’ve lost 3 billion birds--29 percent of the bird population of the US and Canada--since 1970. Leading causes cited included habitat loss and widespread use of pesticides. The Audubon Society reported that by 2080, 389 out of 604 North American bird species will find most of their current ranges unlivable if the climate remains on track to rise by 3 degrees Celsius.

No more loons on US lakes unless we clean up our act-photo Bert de Tilly

    While our national leaders are dragging their feet, what can we gardeners do to address climate change? Collectively our gardening choices can make a real difference. We can do our part by holding carbon in soil and plants, planting strategically to reduce our homes’ energy needs, and choosing materials with less embedded carbon cost.

    You’ve undoubtedly heard that saving trees—for example not burning down the Amazon rainforest or clearcutting Forest Service land in the Northwest—can help combat climate change. The same principle operates in our backyards. Trees hold carbon and keep it out of the atmosphere for as long as they live. Perennial plants also contribute.

Big trees sequester lots of carbon-photo ukgardenphotos

    But you don’t have to hem in your yard with big trees. We can also help by following Earth-friendly gardening practices. Soil sequesters carbon, and the more organic material you add to it, the more carbon it will hold. That means keeping fallen leaves on your property makes even more sense. 

It's not waste, it's precious organic material

    If you’re planting a sizable tree, you can help even more by positioning it to reduce your energy use for heating and air conditioning. Deciduous trees shading the house in summer can provide substantial cooling, and in winter when leaves are down, they allow warming sunshine through. Evergreens that block winter winds can reduce energy needs too.

Trees shading the house save energy-photo American Society of Landscape Architects

    When we’re shopping for materials to use in the garden, we have a chance to avoid high embedded carbon costs. For example, did you know that those little white pellets of lightweight perlite that you see in bagged potting mix come to us from the Greek island of Milos, where volcanic glass is mined and heated to 1600 degrees Fahrenheit to puff like Rice Krispies? Meanwhile, stripping peat bogs for the peat moss in that commercial potting mix releases carbon into the atmosphere and eliminates the carbon sink they provided. 

Mer Bleue peat bog, Ontario

    Instead of buying bags of this environmentally costly stuff, you can make your own potting medium at home. Or you can choose Organic Mechanics potting mix, which is made from compost and coconut fiber, or coir.

Making peat-free potting mix at home

    If you’d like scientifically informed straight talk on how to make shrewd gardening choices that will help combat global warming, check out The Climate Conscious Gardener, published by Brooklyn Botanic Garden.

Sign for the April 2017 Climate March in Washington, DC

The best time to plant a tree is yesterday

Four weeks ago we took down a big section of our 21-year-old wooden fence. Back in 1998, it was in tune with the gardening zeitgeist: an elegant six-foot white-stained construction with vertical slats on the bottom and a section of lattice on the top. For the first few years it looked great.

The wooden fence in 2004, bright and new

    In retrospect, though, I wish I’d chosen something less conspicuous. Soon the weather, acid rain, and tannins from overhanging oaks stained it gray, and frequent wetting by the irrigation system speeded the onset of rot. Sections started to lean crazily. For a while, we could salvage the fence’s integrity with reinforcing metal posts set in concrete. This year I noticed growing gaps between the posts and the panels of slats.

    Replacing the ornamental wooden fence would be prohibitively expensive—just disposing of the rotten fencing cost plenty. So with some trepidation, I opted for an unobtrusive black chain-link fence instead, a big change. Where our view of two neighbors’ yards had been blocked, it’s now open.

The same area as above: beautyberry in front of the new fence

    My plan was to plant some evergreens that would gradually screen our view through the fence and give the neighbors back their privacy. Accordingly, I started looking around for reasonably priced shrubs and small trees. Fortunately it was time for end-of the-season sales. 

    Did I choose all natives? Well, no. I was looking for shrubs or trees that would tolerate some shade and not grow too tall. I didn’t want to repeat my usual mistake and in 10 years find my vegetable and insectary beds languishing in deep shade from full-sized conifers.

November 2018: lots of trees means lots of shade

    A couple of years ago I’d planted two evergreen natives along this fence: an arborvitae said to grow to no more than 14 feet (Thuja occidentalis ‘Smaragd’) and a mountain laurel (Kalmia latifolia).

Smaragd is Old English for emerald

    This fall I was proud of myself for extracting a dwarf Alberta spruce (Picea glauca ‘Conica’) from its ceramic pot. Alberta spruce is a North American native from Canada and the northern states. It had been effectively living as a bonsai, trapped in its container for five years unable to grow tall. 

The dwarf Alberta spruce, left, in its pot, May 2018

With my formidable Japanese hori hori digging knife, I hacked away at the circling roots and managed to pry the plant loose. 

No one will mess with me when I'm wielding my Japanese digging knife

After some radical root pruning, I planted the spruce along the new fence, where I hope it will have a happier life.

The spruce in its new home

    What I ended up buying was another ‘Smaragd’ arborvitae, another dwarf Alberta spruce, and two dwarf Hinoki cypresses (Chamaecyparis obtusa ‘Nana Gracilis’ and C. obtusa ‘Tetragona Aurea’) whose ancestors hail from Asia. So of the seven evergreens along the fence, all but two are North American natives—a sustainable-enough solution, I thought.

Dwarf Hinoki cypress 'Tetragona Aurea' brightens the fence line

    It’ll be a long time before the new and relocated trees recover from transplant shock, start growing, and fill in the space between them to create a meaningful visual screen. Meanwhile, I’ll enjoy the extra light and the open feeling that comes with our new fence.

Take my sustainable gardening course Saturdays October 26 and November 2, and you can judge the young trees for yourself. Sign up here through Newton Community Education.