Helping more by doing less

The Xerces Society, which works to protect invertebrates and their habitats, has created nine handsome posters to advocate letting fall leaves lie. They’re offering them in printable form on their website to spread the word that leaves on the ground are necessary for moths, butterflies, bumblebees, and many other garden contributors.

    The reason to let leaves lie on the ground through the winter is that so many species use that leaf layer for shelter. Most butterfly and moth species don’t migrate. They need to make it through the cold months in some stage of their life cycle, whether it be as an egg, a chrysalis, or an adult. Bumblebees don’t gather in hives, and they too welcome an insulating cover of leaves over the shallow holes in the soil where their queens spend the winter.

Fertilized bumblebee queens survive the winter in holes in the ground

    I’m working to welcome these insects and many others to my garden: leaf-eaters, pollinators, and the beneficial insects that, as predators, keep bug populations in balance. 

Dragonflies are top predators, useful for keeping leaf-eating insects in check

I’m counting on these native insects at the base of the food web to keep my plants healthy and my garden a welcoming place for birds and other animals. The three pillars of this approach are avoiding pesticides, choosing the right plants, and letting those fall leaves lie on the ground.

It might look messy, but letting leaves lie is more sustainable

    To help out native insects, I’ve completely discontinued pesticide spraying, even for nonnative pests without local predators. That’s to avoid killing off native insects with friendly fire. No insecticide is so targeted that it doesn’t cause unintended casualties.

In the woods, leaf litter is free of pesticides and stays undisturbed on the ground.

    I’m also choosing plants with the insects in mind. Last week students at a hands-on Newton Community Education course in the yard helped plant my latest insect-attracting shrub, a New Jersey tea (Ceanothus americanus), adding more native flowers to offer pollen and nectar in spring. 

New Jersey tea flowers offer premium pollen and nectar

This little shrub will grow into a 3-foot mound and attract butterflies and hummingbirds to its white or pale lavender flowers. 

     I’m looking forward to experiencing New Jersey tea’s spring fragrance. It’s drought tolerant once established, which fits with my efforts to water less. Right now it’s leafless, showing a few of the yellow twigs that will stand out in the winter landscape when it settles in. When next year’s leaves fall to the ground, they'll help insects through the winter.

    I could undo some of the benefits of planting insect-friendly perennials and shrubs by bagging up my tree leaves and setting them out at the curb for yard waste pick-up. 

Insects lose winter habitat when organic material goes out as yard waste-photo Bill Barber

The Xerces Society warns that sending away those fall leaves--or chopping them up with a lawnmower or leaf shredder for mulch—would be discarding or destroying insects and their eggs and larvae already sheltering among the leaves.

    Not shredding leaves for mulch will save a lot of time and energy. I can spend some of that time piling leaves around trees and shrubs that could use some extra insulation. And there’ll be time to cook up lots of schemes for moving plants around next spring. That’s the beauty of a garden. It’s never finished.

Sunlight needed

A friend touring my garden noticed I had planted an Asian pear in a back corner surrounded by tall trees. “Won’t it need sunlight?” she asked tactfully. Exactly right—of course that little tree, now three feet tall, is not going to flourish or produce fruit in the shade.

Does this Asian pear have a future?

I’ve faced this problem since I started this garden 33 years ago. Why haven’t I learned by now not to plant sun-loving plants in the shade?

    Since we moved in, our backyard has been shaded by a line of Norway spruces along the southern edge of the lot. This provides useful privacy. But it also means that the garden’s southern exposure, its best chance at full sun for flowering plants, doesn’t get a full day’s sunlight. 

Norway spruces block the southern exposure

The sun has to rise beyond the level of the spruce tops, now above roof level, before direct sun hits my flower bed along the side of the garage. Right under the spruces, almost nothing will grow at all. 

    There’s more shade from a big oak that stands next to the back corner of the garage and a tall white pine near the spruces. 

So many trees, with the oak towering over them all

I spent several years hopefully planting classic sun perennials such as peonies, irises, and Oriental poppies. They put out floppy stems and wan, undersized leaves, reliable indicators of not enough sun. They didn’t make many flowers, and blooms that did open were small and pale.

    I did finally find a place to plant those peonies in a patch of sunlight, and I enjoy seeing them bloom every spring, although they don’t make as many flowers as they would in an open area with no trees or structures nearby. 

Peonies--so romantic!

Meanwhile, as the garden expanded, I planted more trees I loved, which led over the years to more shade. There’s only so much you can do with impatiens, those stalwart shade bloomers. I have to admit that I’ve continued to push the limits, planting part-shade plants in what’s actually full shade, only to learn my lesson once again about the need for sunlight.

For shade: impatiens, torenia, variegated foliage

 

    When we took down hemlocks to avoid killing native insects by spraying for hemlock woolly adelgid, I saw sunlight and quickly popped in some new shrubs and small trees. The self-pollinating Asian pear is a semi-dwarf that’s predicted to grow no bigger than 15 feet tall and 11 feet wide. Two varieties are grafted to the base, so if all goes well, we’ll have two kinds of pears, one type ripening in August and the other in September. 

Picking pears in the yard would be great

That’s a big if. Any pears that ripen in my yard are likely to be greeted enthusiastically by birds, squirrels, and raccoons.

    Before that, the tree will need to get enough sunlight to be able to produce flowers—no flowers, no fruit. I’m hoping I can get by with pruning back the surrounding older, taller trees to give the Asian pear some space. That may be kind of like asking a tree to grow in an apartment building’s air shaft. 

 

A scurry of squirrels

We’re experiencing a squirrel population surge in northern New England. Wildlife experts say it’s because of a bounteous supply of acorns last year. With lots of food to fatten them up before the winter, more squirrels survived until spring, and they had more babies this spring and summer. Now lots of squirrels are crossing New England highways, and some are ending up as roadkill that highway departments have to contend with.

Squirrels are on the move searching for food - photo Michael Palmer

    This explains trouble I’m having with squirrels in my yard. Gray squirrels are digging frantically in the potting soil around my container plants. It’s worst if they’re newly planted and there’s lots of soil unbound by roots. But the squirrels try out all the pots, even ones filled with established plants. I’m not sure whether they’re searching for food they previously hid or checking out new potential cache sites. The result is damage to plants that I want to keep through the winter, such as a new blueberry bush and some promising young strawberry plants just starting to bear fruit.

Netting to keep squirrels out of pot of strawberries

    Investigating this moment in squirrel history, I learned that the expected density of squirrels in wooded areas is approximately two per acre. It feels as if I’ve got about ten living on my third-of-an-acre lot, although I admit I can’t tell one squirrel from another. Researchers deal with this problem by capturing squirrels and marking them or implanting chips in order to track individuals.

Squirrel research - photo USFWS

    Our yard must be a favorable place for squirrels because we have so many trees. It’s fun to watch squirrels circumnavigating the clearing at the back of the house, running along thin branches and stretching or leaping from treetop to treetop without ever having to leave the top of the canopy. The neighborhood is full of mature red and white oaks, including a venerable red oak in our yard, so we’ve got lots of acorns.

Will there be enough acorns for the squirrels?

    I also learned that booms and busts in squirrel populations are expected and common. In the 17th and 18th centuries, when North America was covered with forest and squirrels inhabited more territory, explorers and naturalists observed estimated millions of squirrels migrating when food ran out due to population explosions. The herds of squirrels reportedly ran for up to 100 miles and swam major rivers, including the Mississippi. Squirrel numbers declined in the 19th and 20th centuries, but periodic migrations continued. The most recent major migrations occurred in 1968 and 1985. What a sight that would be!

Add swimming to squirrels' talents - photo Lindsay Trostle

    Of course, the predictable end of a squirrel population explosion is a squirrel population crash. Without enough acorns to feed all the squirrels, some will die this winter, and the survivors will produce fewer young. Then the population will presumably level off again.

Winter is a hard time for squirrels

    I’m not sure how I feel about this squirrel die-off. While squirrels in general may be a problem for the garden, it’s hard not to think of a single squirrel as a conscious individual with her own reasons to survive. So take some strawberries, squirrels. I can spare them.

"If you prick us, do we not bleed?"

Back-to-school energy

Would you like an in-person view of my sustainable gardening techniques? Sign up at Newton Community Education for a two-session course. We’ll meet on Saturdays October 13 and 27 from 11 to 12:30. 

Come see the sustainable-enough garden in real life

I’ll demonstrate a super-simple way to make compost, explain my approach to fertilizer and soil amendments, and showcase some easy-to-grow native plants blooming in my garden. I’ll demonstrate how to make mulch from free materials you’ll find close to home, revving up the leaf shredder so attendees can produce some leaf mulch. I’ll show how you can replace part of your lawn with shrubs and perennials that are more fun and more environmentally friendly than turf grass.

New England asters-pretty, and great for native insects

    This course channels some of the fall energy that’s surging at this time of year. Maybe it’s a holdover from when fall meant the start of a new school year, or maybe it’s just because I’ve emerged from summer torpor now that the days are cooler. Whatever the reason, I’m eager to spend time in the garden, and ideas for improvements are bubbling up daily. 

    Now that the new perennial beds next to the back of the house are settling in, I can turn my attention to two other areas where I’d like to add perennials and shrubs. 

Goldenrod blooming in the new bed

When we planted a dawn redwood (Metasequoia glyptostroboides) in 1997, it was a slender sapling no more than 6 feet tall. Twenty-one years later, it’s done what it was supposed to do—sent out horizontal branches covered with soft, feathery, grass-green needle-shaped leaves. Those limbs have spread wide, and they’re shading out the perennials I planted in front of the tree. At this point, only hostas and other shade-lovers are happy in that bed.

Time to give up on growing flowers in the shade of the dawn redwood

    I’m thinking of carving out a big section of the sorry lawn in front of the bed to make more space for flowers that need a half day of sunlight. I could start by smothering the grass and improving the soil with sheet composting. That would involve putting down thick layers of organic material—it could be wood chips, unfinished compost, straw, or even cardboard or newspaper. After giving them and the lawn grass underneath time to decompose, I could plant through the layers. 

     I’d love to get started this fall. I’m already thinking of lots of plants around the yard that need more sun and could grow better if they were moved to that new area—for a few years, until the dawn redwood overshadows them again.

My redleaf roses could bloom like this if I moved them out of dense shade

    Another place I could add more interest is the front yard, shaded by Norway maples and currently covered with periwinkle (Vinca minor) groundcover. 

Shall I liven up this groundcover bed?

A red-leaved Japanese maple and a couple of hydrangeas rise from the periwinkle, and a row of scraggly yews line the foundation. I started this project two years ago by adding an oakleaf hydrangea (Hydrangea quercifolia) to the front yard, and I’m encouraged by its success. Why not add some more native shrubs that can tolerate shade? It would be fun to try.