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.

A paradigm shift

To switch my garden paradigm to one that’s more wildlife-friendly, I find that I need to keep catching myself when I fall into familiar routines. One of these is the fall garden clean-up. 

Looks messy, doesn't it?

    Conventional garden wisdom advises pulling out annuals and cutting back perennials in fall to prevent unwanted insects from over-wintering on their leftover stalks. My goal used to be to leave the garden beds clear of above-ground herbaceous plant manifestations during the winter. This was when evergreen shrubs and trees were supposed to carry the aesthetic burden.

Evergreens are supposed to provide winter interest

    This year I planted my insectary garden, intending to attract native insects. In October, without thinking about it, I almost followed my usual practice, which had been to cut the plants to the ground after the first hard frost and then blanket the soil for the winter in a thick layer of compost. Luckily I realized this habit wouldn’t fit the new paradigm.
    Providing shelter for over-wintering insects is part of what I’m trying to do now. This year I’m going to leave the annuals and perennials standing through the winter. I spread compost around them, and I’ll cut them down in spring when new growth is about to start.

Insectary garden under the new plan. Parsley is still green.

    This should help birds as well as insects. Check out Gardening for the Birds: How to Create a Bird-Friendly Backyard, a fascinating book by George Adams. He proposes making gardens that offer food, shelter and nesting sites for native birds. That includes attracting insects for birds to eat. It also means leaving flowers alone when they go to seed, because many provide useful food for birds.
    Following Adams’ directions, I’m leaving seed stalks standing on perennial oxe-eye daisies, asters, goldenrod, and coneflowers, and annual sunflowers, cosmos, snapdragons, zinnias, and black-eyed Susans.
    A lot of these plants have similar-shaped daisy flowers because they are from the same taxonomic family, the Asteraceae. In this group of plants what looks like a single daisy is actually a composite of many smaller flowers. The petals are ray flowers, and the central disc is made up of tiny disc flowers.

Black-eyed Susans gone to seed

Apparently this makes for good foraging for both insects and birds. I’ll be watching to see if I can observe birds feeding on the flower heads during the winter.

Leaf mulch--manna from heaven

This week most of the maples on our street dropped their leaves, and the oaks' leaves are starting to fall. This is the last burst of glory before the bare gray and brown landscape of winter sets in. It’s time to make leaf mulch.

Last leaves

            When we bought our house thirty years ago and moved to the suburbs, I imagined that I would let fallen leaves lie on my beds through the winter as mulch. This worked around the fence line, but in more open areas, the leaves wouldn’t stay put. I quickly sensed that neighbors were not happy when leaves blew over from our property to theirs. Local custom demands that yards be absolutely leaf-free going into winter. 

            The reason to use leaves for mulch was not just to divert them from the waste stream. I wanted to keep falling leaves on our property so that nutrients the trees pulled from the air and soil to make foliage could stay here and be recycled. I know that some people have luck grinding up leaves by running a lawnmower over them. This never worked for me, and anyway, I wanted to spend as little time as possible behind the gas-powered machine we used at the time. So I invested in a leaf shredder.

            This electric tool is essentially a string trimmer in a drum. Whirling plastic filaments chop the leaves, and they drop down into a barrel, a bag, or directly onto the soil where they’re wanted. To use the leaf shredder takes some effort, plus goggles, a mask, and wrist-covering leather gloves. It’s loud, and it makes a lot of dust. The plastic filaments wear down and have to be replaced frequently. Sticks clog the drum, so they have to be picked out of the leaves as I feed them in. Leaves that are wet, or even damp, are much slower to process.

            Yet despite the drawbacks, hours spent feeding leaves into the drum prove well worthwhile. The chopped leaves make pleasant, fluffy brown mulch that looks neat and stays where I put it.

Conventional garden wisdom warns against piling mulch against a tree's trunk lest voles or other small animals chew through the bark in winter. That's never happened in my yard.

The leaf mulch lasts for at least a year and improves soil quality by contributing organic matter as it decomposes.

Last year's mulch, almost fully decomposed

            Now I’m in the strange position of not having enough tree leaves. I need more to make the amount of mulch I want. I ask neighbors if I can carry away some of their leaves. They humor me, but they sometimes give me quizzical looks. They don’t know that they’re giving away the garden equivalent of manna from heaven.  

An insect's autumn buffet

This spring I set a goal to have something blooming all season to attract and feed native insects.

            Despite my efforts over the years to plant for flowers throughout the growing season, my garden still has the most flowers in spring and early summer. Flowering trees and shrubs put on their show from late April through June. 

Mid May--a great time in the garden

            The majority of my perennials also bloom in spring. In July I’m down to lilies and daylilies. By August there’s a decided lull

Mid-August doldrums

            This spring I planted a small bed specifically for the benefit of insects (see Bugs welcome), aiming to have flowers available until the end of the garden season, which is coming up soon now. The black-eyed Susans (Rudbeckia hirta) and sweet alyssum (Lobularia maritima) I planted bloomed steadily through the summer. 

Black-eyed Susan flowers are fading, 
leaving seeds for birds.

Sweet alyssum is still going strong

In September, as the summer bloomers went to seed, New England asters (Symphyotrichum novae-angliae) picked up the baton.

A New England aster blooming happily in October

            It’s easy to forget what a great time fall is for flowers. On September 26, 2013 I counted twenty-seven different kinds of plants in bloom in beds and containers. Even now on November 1 there are a few flowers on the last of the fall and summer bloomers, 

Stonecrop (Sedum 'Rosy Glow')

and some spring bloomers are back with a last round of blossoms before the snow sets in. 

Roses that quit in the summer often bloom again
 until surprisingly late fall

            Cold and drought—we’ve had both in the past month—can signal plants to put energy into making flowers and seeds before they die or go dormant for the winter. They sacrifice some of their stored energy toward the goal of passing on their genes. Summer heat puts some plants into a state of dormancy (that would certainly apply to my pathetic lawn grass) in which non-essential functions like making flowers and new leaves are put on hold to save energy. In fall these plants come back to active growth and some resume flowering.

            Other plants take their cue from the length of the nights. Their pattern of flowering in spring and fall is mediated by the balance between two forms of the pigment phytochrome (If you want to know more about this and other nuggets of plant physiology useful to gardeners, I highly recommend How Plants Work, a new book by Linda Chalker-Scott, who blogs at gardenprofessors.com).

            The reason the black-eyed Susans start flowering in June is that they are “long day” (short night) plants, triggered to bloom by shorter summer nights. Dahlias wait until later to make flowers because their signal is the longer nights of late summer and fall.

            Next year I hope to expand my offerings of nectar and pollen at the end of the summer to make sure that insects can find what they need in my yard. It’s all part of a new understanding—we need the insects at the base of the food web so that all the animals, including humans,can eat.

A game of inches

Although I garden in Climate Zone 5B here in eastern Massachusetts, I got a reminder this week that conditions vary in different areas of my yard. The first frost brought an opportunity to observe small differences in temperature between areas as close as inches apart.

            Two pots of wax begonias (Begonia x benariensis ‘Big Red’) next to the front steps offered a striking demonstration of a microclimate, a small area with climate conditions different from its surroundings. The leaves on stems closest to the house stayed green when the night temperature dipped below freezing.

Frost blackened the leaves on stems just inches away on the other side of the large pots. The leaves that died were farther from the warmth radiated by the house’s foundation. 

Before the frost

Leaves farther from the house blackened and melted in the frost

I inadvertently demonstrated another source of radiant heat by leaving a full watering can next to one of the pots. It too absorbed heat during the day and radiated it at night, protecting nearby foliage from frost kill.

The water in the watering can protected the leaves on the left

            My first introduction to microclimates in my garden came when I planted maidenhair fern (Adiantum pedatum). Of three ferns I planted, two dwindled and died and one flourished prodigiously. It’s still with me twenty years later and has gradually produced a small colony. Apparently I’d been lucky enough to plant it in just the right place, on the eastern side of a tall white pine (Pinus strobus) and shaded from western sun by a yew (Taxus x media) and some hulking Catawba rhododendrons (Rhododendron catawbiense) inherited from previous owners.

Maidenhair fern colony in May

            I can’t claim credit for the fern’s success. It was only by chance that I planted it where I did. I can guess that it’s enjoying the right amount of water gently delivered as the pine catches rain on its needles. I knew maidenhair fern was a shade lover—that’s why I bought it. It must also like being out of the wind, sheltered from our prevailing west winds by the shrubs, but with less turbulence than a solid fence or wall would cause.

            The fern colony sits on a gentle slope that runs from the base of the pine to the lawn to its east. That must allow cold air to flow past it to the lawn a few inches below (interesting to know that cold air drains downhill, like water). The ferns are growing under a deep insulating blanket of pine needles and deciduous leaf mulch, which keeps soil moisture and temperature relatively steady.

This week the ferns are enjoying a fresh layer of pine needles

            It’s testament to the breeders’ art that the wax begonias bloomed consistently from May until late October. Unlike the maidenhair fern, they were flexible about accepting the hotter, drier conditions I provided. Now I’ll see if I can root one of the stems indoors and keep it going in yet another microclimate, next to a cold west-facing window in a heated room.