Coming soon

Dear readers, 

I’m pleased to announce that my book The Sustainable-Enough Garden will be published early next year. I can’t wait to share it with you.

     The book tells the story of my journey toward sustainable gardening. It started with compost. When I started my first compost pile, I imagined I was going to make fallen leaves into rich, black compost in just one season. Like a lot of other gardening skills, composting turned out to be a lot more complicated than I expected, but when I got the knack, it involved doing less rather than more.

    Gradually I learned to garden, partly by reading and taking classes, partly by trial and error. I wanted to bring my gardening practices in line with my environmental principles. I thought I was doing pretty well. 

Sweet alyssum for pollinators, with a volunteer mullein

     Then in 2010 I got a reality check when I read Douglas Tallamy’s book Bringing Nature Home, with its account of a crisis for native insects that need particular native plants for food, shelter, and reproduction. Inspired to be part of the solution, I took another look at my gardening practices, including plant choices, to see how I could make them more sustainable. I’ve spent the last five years working on this and writing about it.

Offering nectar for bees

     Is my garden completely sustainable now? No, but I'm getting closer. I wrote the book to describe the realistic middle path I’ve charted between conventional gardening practices and purist edicts that don’t fit the busy lives of many home gardeners.

    A wonderful book designer, Barb Cottingham, is at work now making the book attractive and inviting. Next it will go to the indexer, and then it will be published by Amazon CreateSpace, which will produce copies on demand, probably starting late this winter. I’ll let you know as soon as Amazon is ready to start taking orders.

    Thank you for reading my blog. I hope you’ll enjoy the book as much as I’ve enjoyed writing it. See you in 2016.

When thawing is a bad thing

This year I tried a new approach for a difficult spot in my garden—an ornamental grass for a place where winter goes away temporarily when we dry our laundry.

      We had planted three boxwood shrubs (Buxus sempervirens) in a small north-facing bed next to the driveway. 
 

Happy  boxwood

They were expanding and thriving until we added two new dryer vents two summers ago. Having three vents instead of one definitely shortened the time it took to dry clothes. 

      Unfortunately, this gain in energy efficiency meant a death sentence for one of the boxwood shrubs, which stood right in the warm air outflow. By this spring, all the shrub’s leaves had yellowed or fallen off. I bowed to the inevitable and cut it to the ground. 

The unfortunate boxwood sprouting from the base this summer

As I understand it, what killed the boxwood’s leaves was desiccation.  

      As the nights get longer, trees and shrubs prepare for freezing temperatures by moving sugars they’ve made through photosynthesis into cells. Once there, the large molecules act as antifreeze, preventing the water in the cells from freezing, expanding, and bursting the rigid cell walls. (If you’ve ever over-filled a freezer container, you can imagine this process).

      Deciduous plants don’t have to protect their foliage from freezing. They cut their leaves loose and defend only their woody trunks and branches. But boxwood holds its evergreen leaves through the winter. Although the plant is dormant, it needs to maintain a low level of metabolism even in the cold to keep the foliage alive. 

      The problem is that during winter thaws—or when air from the dryer creates a warm patch around the shrub—metabolism speeds up. The leaves may open their stomata, pores that let in carbon dioxide for use in photosynthesis. This allows water vapor to escape. If it goes on for too long, the leaves dry out and die. 

      I pondered what to grow in place of the dried out boxwood. Another evergreen shrub would probably suffer the same fate. I needed a plant that could get by with mostly indirect sunlight in the bed’s northern exposure. I wanted something similar to the boxwood in height, width and density.  With my new goal of providing habitat for native insects, I preferred to replace the nonnative boxwood with a native plant. 

    I considered several bulky perennials, theorizing that since the above-ground part of the plant would die off, inconsistent air temperatures in winter wouldn’t be a problem. I decided on switchgrass (Panicum virgatum ‘Shenandoah’), a selection of an adaptable ornamental grass native to most of North America that has burgundy summer foliage. 

'Shenandoah' switchgrass in early summer

It came home from the nursery already quite tall (its expected full size is 4 by 4 feet) and soon sent up airy pink seedheads. It settled in with no fuss, apparently unfazed by intermittent blasts of hot damp air from the dryer during the summer.

      Next spring I’ll find out whether I was right in guessing that the switchgrass’s roots would survive the winter despite the challenging conditions next to the vents. 

Switchgrass, far left and ready to be flattened by snow, is positioned
 right where warm air comes out of the new vents

The best among bad choices?

This is the time of year when small gray-brown winter moths (Operophtera brumata) congregate on windows and storm doors at night, sometimes fluttering into the house. These nonnative insects have staged a major infestation in Massachusetts since 2001, and they have me in a dilemma.

Male winter moths hanging out on a window

    Starting around Thanksgiving, the moths mate, and the females lay their eggs on trunks and major branches of trees. They particularly like maples, oaks, crabapples, and blueberries. Those are some of the key species in my yard. The larvae, tiny caterpillars, hatch in spring, wiggle into buds, and eat young leaves. 

    Weakened by losing a large proportion of their leaves to the caterpillars’ depredations, the trees may die because they lack the energy to put out a new crop of foliage. I can see this happening to street trees in the neighborhood. Some have died; many are very stressed.

This birch lost many leaves to winter moth caterpillars

    I’ve been having my trees sprayed with a (somewhat) natural product called spinosad that kills winter moth caterpillars when they’re eating leaves in spring. I do it to save the trees, but I don’t feel good about it. Spinosad kills by its action on the caterpillar’s nervous system. It’s extracted from the bacterium Saccharopolyspora spinosa, which is fermented to derive the active ingredient. 

    Spinosad has low toxicity for mammals and birds and spares many insect predators and parasitoids that we count on to control leaf-eaters. The problem is that it kills not only winter moth larvae but other insects too. I was alarmed to learn that it can kill honeybees if it’s applied while they’re active, as when flowering trees are blooming in spring and bees are foraging. Once the spinosad dries, it becomes less dangerous to bees. 

I don't want to kill bees by spraying spinosad

    So which choice is correct, to spray or not to spray? I’m torn between wanting to save trees I love--losing the hundred-year-old oak near the house would be particularly sad—and recognizing that by spraying spinosad, I’m altering the balance of insects in my yard and killing off some natives participants in the local food web. I could let the winter moth caterpillars do their worst and see which plants survived, but so far I haven’t had the heart for such an austere approach. 

I'd hate to lose this red oak

    In the next few years, biological control may let me off the hook. Winter moth originated in Europe. Because it didn’t evolve here, it has no native predators. A team led by UMass scientist Joseph Elkinton has spent a decade releasing a predator of winter moth in New England.    

     The silver bullet is a European parasitic fly, Cyzenis albicans, which controlled winter moth outbreaks in Nova Scotia and the Pacific Northwest. The flies eat winter moth caterpillars when they pupate in the soil. They’re specialists, so they don’t affect other species. Their population is expanding. 

Cyzenis albicans

    I like the idea of getting rid of winter moths without chemicals. I wonder, though, about unforeseen risks of introducing nonnative insects to kill the nonnative insects we’ve already introduced accidentally.