My book and web site

Check out my book, The Sustainable-Enough Garden, available on Amazon, and the book's web site at See more plant photos on Instagram.

Sunday, August 27, 2017

Squirreling away acorns for winter

Acorns are falling. I swept the deck yesterday afternoon, and by this morning a few dozen more acorns dotted the surface. They’re a sign that autumn isn’t far off, and for squirrels, they’re the start of the fall harvest.

Red oak acorns

    Gray squirrels are so much part of our suburban surroundings that we tend to overlook their activities. To remedy this, I opened North American Tree Squirrels, by biologists Michael Steele and John Koprowski. Steele and his colleagues and students designed clever experiments to elucidate the feeding behavior of squirrels they found on their campus at Wilkes University in Pennsylvania.

Eastern gray squirrel (Sciurus carolinensis)

    For gardeners who like oaks, it was good news that acorns can be half eaten and still germinate and produce seedlings. Steele noticed that in early fall, when acorns were plentiful and the weather was still warm, squirrels usually ate acorns of white oaks but cached red oak acorns for later. White oak acorns are programmed to germinate in the fall.

Squirrels may pretend to bury acorns in decoy locations

    The red oaks play a longer game. Their acorns contain higher levels of tannin, a nasty-tasting chemical that protects seeds from predators. They’ve evolved to germinate in spring after a necessary cold period. The researchers observed that later in the fall, squirrels started removing the acorn caps to eat just the tops of the red oak acorns, which contained more high-calorie lipids and less tannin. As winter set in, they were willing to eat the whole red oak acorn, tannin and all. Apparently like us, squirrels balance tastiness versus health factors when they choose food.

Health food or tasty treats? It depends on the time of year

    Do gray squirrels remember where they hide their acorns? It was long thought that they didn’t and had to sniff out buried acorns. Lucia Jacobs, then at Princeton University, showed through an ingenious experiment that squirrels found their own cached acorns more readily than those hidden by other squirrels, although others’ caches might be quite nearby. 

Squirrels remember where they hid their nuts--photo by Juraj Patekar

    As a directionally challenged navigator, I’m awed by squirrels’ ability to recover their hidden nuts. Scientists asked whether squirrels were just good at retracing their steps—I can usually do that—and were finding their caches that way. Or were they constructing a three-dimensional mental map that allowed them to locate their hidden acorns? 

    Another of Jacobs’ lab experiments confirmed the latter. If she trained squirrels to find a nut in a maze and then kept the nut in the same location but changed the way to get there, the squirrels still found the nut. They’d retained its location, not just the directions for getting there.


    Although squirrels recover most of the acorns they store, they do serve red oaks by dispersing their seeds. A study of white versus red oak seedlings found that most of the white oaks sprouted close to the parent trees, whereas red oak seedlings appeared three to six times farther from the mature trees, their acorns having been moved by squirrels and other animals. In this way, squirrels contribute to the development of our forests.

Sunday, August 20, 2017

Pollinator-safe container plantings--do they work?

This spring I refrained from filling my shopping cart with brightly-flowering annuals at my favorite garden center. It felt like a deprivation, but I was trying to avoid bringing home plants treated with pollinator-killing neonicotinoid insecticides. 

What I aspire to--the pollinator garden at Locust Grove in Poughkeepsie

This meant changing my approach to container plantings. Now in August the garden is quiet, but the containers are coming into full bloom. It’s a good time to assess how the new approach worked out.

    I’d fallen into a routine of filling large containers with a combination of tender perennials and annuals from the garden center. 

     I carry warm-climate perennials, cannas, elephant ears, dahlias, and a favorite salvia, through the winter by storing them in the basement. Since most of my containers stand in full or part shade, I’d been adding shade-tolerant long-blooming annuals such as impatiens, browallia, torenia and coleus. 

Browallia blooms in shade

I liked the results, but truth to tell, the combinations hadn’t varied much in years. It was high time for a change.

    This year I followed Patricia McGinnis’ suggestion to “shop” in my own garden for perennials to use in the pots. I also found three places in Massachusetts to buy plants that haven’t been sprayed with pesticides: Thomson’s Garden Center in Salem, Allandale Farm in Chestnut Hill, and the horticulture program at a local school, Learning Prep School in Newton. 

Here’s how my containers turned out:

I surrounded Canna ‘Bengal Tiger’ with anise-scented sage (Salvia guaranitica), which just recently opened its deep blue flowers. 

There aren't many flowers as blue as this salvia's

A few marigolds added as fillers have bloomed continuously, adding a bright touch.

Neonic-free marigolds add a pop of color

    My favorite this year is a combination of another canna with an ornamental grass, name unknown, that I bought at Learning Prep. From the flowers (those wispy stalks at the top), I suspect it may be a reed grass (Calamagrostis).

A mystery grass turned out to be a good collaborator

Golden creeping jenny (Lysimachia nummularia ‘Aurea’) is adding a je ne sais quoi as a “spiller” falling over the edge of the pot. Heaven knows there’s plenty of this groundcover in the garden; it’s famous for its imperialistic tendencies.

    In shade, the giant leaves of elephant ears provide bulky focal points. To their pots I’ve added a purple-leaved heuchera for some contrast and offspring from an angel-wing begonia I bought last year that will offer pale pink flowers as the weather cools. 

Contrasting leaf colors and forms complement elephant ears

I doubt the begonia is neonic-free, but I couldn’t bear to throw it away. Japanese painted fern (Athyrium niponicum var. pictum) pops up anywhere shady in the garden. Not surprisingly, it’s willing to collaborate with elephant ears.

Japanese painted fern is an adaptable shade-lover

    Apple-blossom-pink geraniums are doing OK in part shade in the front yard, helping to cover up a not very decorative drain cover that we have to keep accessible. In Salem I found red coleus that’s growing well in a north-facing spot along the driveway.

Coleus without the pesticide spray

    The more I scrutinize the combinations in the pots, the more I can see ways I’d like them to be different. But overall, I’d say that for container plantings, there’s life without neonics.

Monday, August 14, 2017

How it should be done

Yes, a garden can be both sustainable and beautiful. My faith in this ideal got a big boost Saturday when I visited garden designer Robin Wilkerson’s enchanting home garden in Lincoln, Massachusetts. She opened her site to visitors as part of a native plant tour organized by the Ecological Landscape Alliance.

The entrance to Robin's sustainable garden

      Robin’s house and garden sit on old farmland that had been taken over by nonnative invasive plants. For 20 years she has been reclaiming expanding portions of the lot for her organic garden, tearing out unwanted plants and sheet mulching with cardboard and wood chips to smother unwanted vegetation. She grows a large vegetable garden, grapes, berries, and numerous fruit trees.

Beds of bird- and pollinator-friendly shrubs and perennials lead to fruit trees in the background

    Unlike me, she’s resisted planting tall trees that would shade sunny areas. Her flowers enjoy full sun. There’s also a shady woodland section. 

    I had attended a workshop Robin taught at New England Wild Flower Society’s Garden in the Woods on native shrubs for garden use. Her enthusiasm for these plants was contagious and reinforced by a tour of the garden on a lovely June day. Afterward, though, second thoughts set in. 

    Many of the plants she’d showcased had medium-green, medium-sized leaves. They might have pretty fruits and bright fall foliage, but their flowers were often small, off-white, and not very eye-catching. I thought that a garden of these shrubs would look like a typical New England woodland edge, generally pleasing but not particularly striking or ornamental.

    Seeing Robin’s garden, though, I suddenly got it.

A peach tree, ornamental banana, and hanging basket of calibrachoa blend with native honeysuckle and phlox

While supporting biodiversity and welcoming wildlife, she’s combined natives and nonnatives in a harmonious blend of flowering plants from New England and around the world. The natives she’s planted are shown at their best through thoughtful combinations of shapes, sizes, and leaf colors and textures. 

It's all in the design

    She has large, thriving patches of a long list of pollinator-friendly plants. Plentiful fruit beckons to both humans and birds. 


She’s lined the lowest point in the lot, the back border, with a barrier made from pruned twigs and branches; 

This homemade fence provides shelter for insects and other animals

in addition to demarcating the lot line and preventing erosion, this provides a home for insects and other animals. For birds, she keeps several dead trees topped at around 20 feet standing behind the garage. These snags are valuable to woodpeckers and others that feed on insects beneath the bark and build their nests in tree cavities.

Dead trees offer food and habitat for birds

    Insects were everywhere. In addition to the many bees working flowering perennials, butterflies were wafting all over the yard, 

Black swallowtail nectaring on a tithonia flower

and I spotted a hummingbird moth. That was just while strolling around gawking at the flowers; I’m sure closer observation would find that this garden hosts a full range of insects in dynamic balance.

    Robin’s is the kind of garden I aspire to. The visit immediately got me thinking about how to emulate her dense plantings and thoughtful combinations of natives and exotics. Next, the front yard!

Sunday, August 6, 2017

Let it rain

What a lush garden year we’re having! Last summer’s gardens were parched by drought. This summer the Northeast has been blessed with plentiful rain. 

Foliage is thriving thanks to plentiful rain

As of August 6, we’d had 30.83 inches of precipitation in the Boston area in 2017, well above the average of 25.88 inches by this date. You can probably see the difference in your garden; I certainly can in mine.

    Why should that be? What makes rain better for gardens than irrigation? We run a sprinkler irrigation system, so unless I cut back on scheduled watering, my plants should be getting enough water even when it doesn’t rain.

Water beads on a giant elephant ear leaf

    There are limitations to even the best-designed irrigation system. Ours is set up in 12 watering zones. Twice a week, sprinkler heads pop up in the early morning and start spraying in a programmed sequence, controlled by a computer in the basement. A rain sensor prevents watering when there’s been adequate rain. With this system, I lavish a lot of water on the garden, sometimes more than my conscience tells me I should.

    Theoretically every plant gets plenty of irrigation water, but in practice, I’ve learned, it’s not that simple. As the garden has matured, shrubs have grown wide and tall, hogging the spray of water and creating dry shadows behind their bulk. And the arcs described by the sprinklers’ spray don’t fit exactly to every angle and curve of plantings. Inevitably some patches get less irrigation.

    Beyond falling evenly on the whole garden, rain conveys numerous advantages:

Lots of rain is helping this St. John's wort get established

•    Whereas irrigation water contains dissolved minerals, including calcium, magnesium and sodium, rainwater is “soft” and mineral-free. As a result, it pulls nutrients by diffusion from where they're bound in the soil, making them available to plants’ roots.
•    Rain water is acidic, which promotes release of micronutrients including zinc, manganese, copper and iron that plants need. Most of my garden soil is acidic already, but there may be alkaline areas where concrete paving leaches lime. Acidic rainwater is especially beneficial in those spots.

Soil next to sidewalks may be alkaline

•    Rain falls at 20 miles per hour, penetrating soil better than irrigation water, which falls at 5 mph.
•    Rain is saturated with air, so it oxygenates soil. That’s good for plants
•    Rain contains nitrogen in the form of nitrate and ammonium from the air. This nitrogen becomes available to plant roots and promotes growth.

Big canna leaves can use a boost from extra nitrogen in rain

•    Rain doesn’t contain the chlorine that comes with treated drinking water. Chlorine inhibits plant growth.
•    Rain flushes salts (such as road salt) that inhibit growth through the root zone and washes mineral deposits, dust and pollutants off leaves, making for more effective photosynthesis.

The proof is in the pudding. The garden looks happier this year with more rain. 

New plants I added in June and July are surviving, despite the heat. Just watering them might not have been enough if it hadn’t been for well-timed, frequent rain.