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.

A reminder: don't forget the pollen

This month I’m inadvertently demonstrating a point about nonnatives and double flowers. I bought some plants for their flower color, and the result reminds me to stick to my new selection priorities.

    Three weeks ago I realized that some of my container plantings were looking sad and could use an upgrade. Two were filled with variegated foliage of Swedish ivy (Plectranthus coleoides) for a shady spot near the front steps. After three months, the plants had grown large, but I was finding them boring. Meanwhile, in a pot on the back deck, a color clash had developed between two zinnias, one with sunflower-yellow flowers and the other salmon pink. I moved the yellow-flowered plant to the insectary bed.

Bees like it, but the color didn't work for me

    Then inspiration struck. I remembered that when local garden centers put out fall chrysanthemums, they’re usually accompanied by some asters loaded with buds and ready to bloom. A pink-flowered aster could add pizzazz to all three of these pots. Plants already covered in buds would bloom whether they got a lot of sun or not.

There might be some asters among the chrysanthemums-photo Elvert Barnes

    I went to my favorite neonic-free garden center looking for pink flowers. I seized on the only pink aster on offer, probably a Chinese aster (Callistephus chinensis). The plentiful buds hadn’t opened yet, but the label said they’d be pink. I brought three plants home and popped them into the pots that needed more zip.

    Now that the flowers have opened, I’d call the color magenta, not pink. The new asters brighten the pots, but they aren’t offering forage for pollinators the way I’d hoped they would. It’s especially obvious in the backyard. A few feet from the new blooms, the blue flowers of a single New England aster are drawing dozens of bumblebees. 

This single-flowered native aster draws lots of bees

The pompom flowers of the new plant just sit there in solitary, sterile splendor. That used to be fine with me, but it doesn’t mesh with my recent focus on supporting a diverse population of insects, especially pollinators.

Sparse pickings for pollinators

    I think there are two reasons that the new asters aren’t getting any visitors. First, they’re nonnatives, so they don’t offer pollen that native insects need. Second, the flowers are double. They have more petals than the nearby blue aster flowers but hardly any yellow central disk. They have little nectar for visiting insects. When growers breed plants for double flowers, the pollen-carrying stamens are often replaced by extra petals. Although the resulting flowers look fuller, they don’t do anything for pollinators. Better choices would have been single pink New England asters such as ‘Alma Potschke’ or ‘Harrington’s Pink’.

There are nice single-flowered pink asters out there

    One of the reasons I flubbed this flower choice is that there are so few local garden centers reliably offering plants that haven’t been treated with pollinator-killing neonicotinoid insecticides. I hope that by next fall more of the area’s garden centers will have announced that they’re neonic-free. Then the pollinators and I will have more options.

    The sustainable gardening course I’m offering in my yard is coming up soon, Saturdays October 26 and November 2. Check out the catalogue listing here through Newton Community Education.

What I put up with for love

A new puppy is testing my tolerance for garden mayhem. Lola is a 4-month-old beagle mix who was brought up from Louisiana with her littermates to find adoptive homes in Massachusetts. She’s playful, affectionate, and all-around lovable. And she’s making a mess of the garden.

Lola's first day in her new home

    The first thing to go was a big puff-ball of ornamental grass, prairie dropseed (Sporobolus heteroleptus). When Lola first explored the yard, this plant attracted her irresistibly. Within in a few days, it was flattened. All the slender leaves were lying on the ground around the stubbly remaining base. Why this species and not a nearby dwarf fountain grass (Pennisetum alopecuriodes ‘Hameln’)? Search me.

Prairie dropseed trying to resprout

    Let’s face it, puppies chew and bite. Lola plucks leaves off container plants, chomps on sticks she finds on the ground, and gnaws on my gardening sneakers. That’s pretty much expected.

    Also predictable is how much she loves digging. The sight of me digging tempts her to join in. Rodent burrows drive her into a frenzy. 

Excavating a vole's burrow?

She’s developed a game: take a plush squeaky toy outdoors, dig a hole for it, drop it in and cover it by nosing soil back over it, then go back an hour or a few days later and “find” it, with great joy. Once she’s run around the yard with the muddy prize in her mouth, she starts digging another hole for it. This is cute when she chooses an inconspicuous digging spot behind large shrubs. It’s infuriating when she wants to uproot my favorite peonies to bury her treasure.

Please, not the peonies!

     I’m reduced to putting up mechanical barriers improvised from fencing and hoop stakes and applying bitter apple spray, which is supposed to make things taste bad—both only mildly successful. From what I’m learning, training is all about “capturing” the dog behavior you want and rewarding it. I guess that means when she digs in the right place, she should get a treat.

    My idea of a good digging spot would be the compost bin. Lola loves to pull out and chew half-made compost components such as rotting stems and chunks of turf. So far she hasn’t buried anything in the compost. That can be a goal to work toward.

How about burying things here?

    Usually I defend my garden fiercely. I shooed the kids out of the perennial beds. When my husband killed a succulent near the barbecue grill that he thought was a weed, I was hurt and indignant. A neighbor who cut back branches on my side of the fence got an angry letter.

    This feels different. Lola’s a baby, and I hope she’s going to grow out of her destructive ways. In the meantime, I’m glad it’s fall, because I can tell myself the foliage she plucks or tears was going to drop off soon anyway. The holes she digs will soon be camouflaged by falling leaves.

They can't fall too soon this year

    Spring will be the real test. Can I stand to watch her destroy fresh new leaves and flowers? I hope I won’t have to.

There’s still time. If you’d like to attend a sustainable gardening class in my yard Saturdays October 26 and November 2, you can sign up here through Newton Community Education.

Lots to love about leaf mulch

The word is out: leaf mulch is great. 

Shredded leaves make high-quality, free mulch

   I’ve been chopping up fall leaves for mulch since sometime in the 1990s. These days I mulch most beds with whole leaves, because they provide shelter for over-wintering insects. I still use chopped leaves for areas near the lawn, because they don't blow around. 

     Many people chop leaves with the lawnmower. I prefer to use a standing leaf shredder, essentially a string trimmer in a drum. Plastic filaments whirl around and chop the leaves into small shreds. The resulting mulch is pretty, it doesn’t blow around like whole leaves left on the ground would, and it’s great for building soil fertility. And the electric-powered shredder doesn’t generate exhaust.

Electric leaf-shredder doesn't pollute the air

    The Rose Kennedy Greenway, the linear Boston park created in 2008 when the Big Dig moved the highway underground, uses organic methods and has recently experimented with switching from bark mulch to shredded leaves. The product they apply, which you can now buy from landscapers, has a step added to my process. After the leaves are chopped, they’re composted for a year. Horticulturists for the Greenway find the composted leaf mulch is full of beneficial soil organisms.

Rose Kennedy Greenway-photo Tim Grafft/MOTT

    As their test area, the Greenway chose a section of the garden devoted to New England native plants. After three years, they’ve found substantial benefits. In the leaf mulch beds they’ve measure increases in soil organic matter. They’ve also found increased cation exchange capacity, which allows soil to hold on to nutrients and buffers it against excess acidity. In fact, the soil in these beds has improved so much that Greenway staff have to consider whether the soil may become too rich for their native plants.

    One of the few drawbacks of leaf mulch at the Greenway has been small fires in the mulch from discarded cigarettes, which apparently isn’t a problem with bark mulch. Let’s hope visiting smokers can learn not to throw cigarette butts into the garden!

It counts as littering

    The City of Newton passed on a recommendation from Michigan State University for mulching lawns with chopped leaves. Lawn lovers hate the idea of letting leaves lie on lawns through the winter, where snow piled on matted leaves can kill the grass. That’s is one of the reasons for our suburban cultural taboo against letting fall leaves lie.

No fall leaves allowed on the lawn

    Instead of doing all that work raking and bagging the leaves, though, MSU turfgrass scientists found they could save time and improve lawns by chopping the leaves on the lawn with a few passes of a lawn mower. The little leaf fractions sift down out of sight among the turf plants, providing a mulching function that suppresses dandelions and crabgrass by up to 100 percent after three years. The decomposing leaf shreds also fertilize the lawn.
 

Chopping leaves with a lawnmower-photo Rebecca Finneran, MSUE

    My focus when I chop up fall leaves has been on improving the soil for shrubs, vegetables and perennials. The lawn is on its own. But after hearing the MSU results, I think I’ll set up my leaf shredder on the lawn this fall to spread some of those leaf bits around while I make mulch for the beds.

Perennials could share some leaf mulch with the lawn

    I’ll be demonstrating the leaf shredder in action at a hands-on sustainable gardening course in my yard Saturdays October 26 and November 2. You can sign up here through Newton Community Education.

Vines with volunteer spirit

In addition to the vines I wrote about two weeks ago that I chose and planted, I’ve got several climbers growing in the yard that showed up on their own. The most useful of these volunteers is Boston ivy (Parthenocissus tricuspidata), the vine that gave the Ivy League its name.

Boston ivy 

    Our Boston ivy appeared on the fence that divides us from our neighbors to the south. It keeps the fence covered in green leaves through the growing season. It’s also acting as a groundcover in a corner where nothing else will grow. 

Boston ivy covers the ground in the dense, dry shade of Norway spruces

The three-pointed bright green leaves turn yellow to scarlet to red-purple in fall. It attaches to supports with holdfasts, sticky discs on the ends of its tendrils, and reportedly grows to 50 feet long. When I follow a shoot I want to remove from a bed or a tree trunk, I can testify that it reaches that length in my yard.

Boston ivy's romantic fall color

    The secret to this vine’s success is that birds like to eat the blue-black berries; Boston ivy is in the grape family. A native of Asia, not New England, the vine has spread around the area as birds drop seeds in favorable growing spots. I don’t regret having it in my garden, because I’d be hard put to find another vine that would cover that fence so thoroughly with so little help from me.

    Two other members of the grape family have also found a place in the yard. I recently spent some sweaty hours pulling wild grape canes (Vitis vinifera subsp. sylvestris) off the shrubs that overhang another section of the same fence. The vines had rooted behind a neighbor’s shed. 

Wild grapes climbing a truck-sized Catawba rhododendron

By the time I noticed them on an infrequent visit to check for places a new puppy could tunnel under the fence, they’d reached far over my head. I had to cut back the leatherleaf viburnum branches (Viburnum rhytidophyllum) that supported them and pull and hack off the vines that came down with them. 

    Wild grapes are nice looking, but I didn’t want their shade to kill the shrubs, and they were bidding fair to take over a large section of the canopy in our yard. Like Boston ivy, they’re imports, in this case from the Mediterranean, and like it they’re spread by birds. I’ll have to remember to be vigilant about checking every year to cut them back as they continue venturing over the fence.

    The third grape relative I’ve found in the garden is Virginia creeper (Parthenocissus quinquefolia, named for the five leaflets that make up its leaves), a cousin of Boston ivy. So far I’m only seeing little patches in uncultivated spots. 

Virginia creeper getting started in a shady area

I welcome this vine because it’s a native and because I love its bright red fall color. When we replace a rotting wooden fence with chain link later this month, I could move one of the young vines to the fence line to create some quick visual screening.

Virginia creeperr's autumn splendor-photo Moralist

Want to see the vines in their fall colors? Sign up here with Newton Community Education for a hands-on sustainable gardening course in my yard Saturdays October 26 and November 2.

Pollinator-friendly container plantings

Every spring I fill 10 or 12 large containers with flowers and foliage plants for summer enjoyment. At this time of year, there’s a pause in the garden action. Foliage is looking shopworn and dull. A few flowering plants whose growth shut down during the hottest days are coming back to life, preparing for an autumn round of bloom. 

Phlox and a few zinnias are blooming in the late summer lull

Buds are swelling on the New England asters (Symphyotrichum novae-angliae), but few have opened yet. This seems like a good time to evaluate how the container plantings have turned out.

    My favorite pot this year was inspired by advice from reader Patricia McGinnis. Two years ago, Patricia pointed out that instead of neonicotinoid-treated annuals from the garden center, I could fill my pots with divisions of perennials from the garden. What a breakthrough!

    Last fall I’d potted some unneeded perennials with thoughts of passing them on to students at my spring sustainable gardening course (If you’d like to attend the fall course in my garden on Saturdays October 26 and November 2, you can register here through Newton Community Education). Some didn’t find a new home, so I used them to design a pot for a prominent position in the front yard.

Perennial divisions fill out a front yard container

    A purple-leaved heuchera, a nativar, makes a solid mass in this arrangement. Nonnatives provide contrasting foliage: a hosta with chartreuse leaves banded with blue-green and a Japanese forest grass (Hakonechloa macra) with similar yellow-gold coloring. I bought an ostrich fern (Matteuccia struthiopteris) to add some height and added white-flowered wax begonias to bloom nonstop through the season. The begonias' shiny round leaves add another texture to the composition. I knew the fern and begonias were neonic-free, because I’d gotten them at a local farm and garden center that promises untreated plants.

    My next favorite container plantings this summer feature nonnative combinations I’ve been repeating over the years. The “thriller” in these pots is Canna ‘Bengal Tiger’. 

Yellow-striped leaves make Canna 'Bengal Tiger' stand out

I store the roots in the basement through the winter, so I don’t have to worry about neonic-treated replacements. I do the same with the giant tuberous roots of elephant ears (Colcasia esculenta). 

Like cannas, elephant ears need their roots stored indoors in winter

The canna has orange blooms, but I usually cut off the flower stalks so top-heavy plants won’t tip over in a heavy wind. To fill in around the canna stems in a pot that’s located in shade, I added white-flowered impatiens. In two pots on the deck that get afternoon sun, I combined the cannas with cobalt-blue lobelia (Lobelia erinus). 

    This year I’ve had success with another conventional flower choice: a big pot full of apple-blossom pink geraniums. 

Taking a break on a geranium flower. Is it a cricket?

I’d bought three of these plants at a pesticide-free garden center two years ago. I’ve kept subsequent generations alive by taking cuttings in fall. This way I don’t have to search every spring for neonic-free geraniums.

    These are the adaptations that have allowed me to keep neonics out of my pollinator-friendly garden. I’m also happy that my peat-free potting mix is succeeding in providing sustenance for the container plantings.

Coleus thriving in potting mix made from compost and coconut fiber

Corralling climbers

As a garden fills up at ground level, it’s tempting to go for vertical growing space by adding vines. I’ve done my share of this in recent years. I’ve learned that their vitality and vaulting ambition can be either a boon or a disaster.

Honeysuckle can be a pleasure or a monster, depending on conditions

    Take hardy kiwi (Actinidia arguta). I’d received a specimen of its variegated cousin, Actinidia kolomikta, as a membership bonus from the Arnold Arboretum.

Variegated hardy kiwi-photo David J. Stang

It grew moderately where I planted it against a north-facing wall along the driveway. I thought another member of the genus would be similarly docile, and I ordered male and female seedlings so that hardy kiwi could produce grape-sized kiwi fruit.

'Weiki' hardy kiwi

 
     Too bad I didn’t investigate the vines’ growth habits, because both hardy kiwis grew far too vigorously for my purposes. They quickly grabbed low-hanging spruce branches, and they looked ready to conquer the 40-foot spruce within a season. In the wilds of East Asia, they can reach 100 feet by scaling tall trees.

Hardy kiwi reaching for the sky-Jo Zimny photos

    My climbing hydrangea (Hydrangea petiolaris) is the apple of my eye. But it too was a lot more ambitious than I expected. In its first 10 years, the vine got a firm hold on an adjacent oak. It began producing its romantic clouds of white flowers in June. 

Climbing hydrangea in bloom

Instead of twining like the kiwis, climbing hydrangea attaches to its supports with adhesive disks called holdfasts. While covering more of the trunk every year with flowers, it’s also formed a mat on the metal garage roof, creating a microenvironment where Oriental bittersweet (Celastrus orbiculatus), a nonnative invasive vine, has found a foothold. 

At 20 years, the climbing hydrangea has taken over the garage as well as the oak trunk

     Birds must have dropped bittersweet seeds on the roof, and now bittersweet wands are reaching for oak branches. 

Bittersweet berries attract birds, as well as makers of holiday centerpieces

These strangling vines really could kill the tree. I think the only definitive solution will be to cut the hydrangea vine off the roof to eliminate the trap for leaf litter that incubates bittersweet seedlings.

    Less vigorous are the many varieties of clematis I’ve planted. Their flowers are so enticing that I can’t resist buying new ones. Clematis are reputed to prefer having their heads in the sun and their feet in the shade. I’ve found that they also need a minimum of competition and plenty of coddling. I’ve had best luck with an old-fashioned variety, Clematis ‘Jackmanii’. 

Clematis 'Jackmanii'-photo k yamada

It flowers reliably in a sunny spot along the driveway. More recently I’ve tried training clematis up trees and shrubs. They hold on by wrapping their petioles (leaf stalks) around twigs, so they don’t kill supporting plants. 

    As with so many plants in my yard, the controlling factor for my vines is how much sun they get. A clematis growing in sun on a tuteur in the insectary bed produces bounteous elegant blue flowers in May.

Clematis in its happy place

Other clematis vines grow lots of stems and foliage but not many flowers as they climb under the shade of supporting trees. Those too-shaded clematis may not flower profusely, but they don’t try to take over. It’s a delicate balance.

Would you like to see how the sausage is made? I'm offering a fall gardening course in my yard on Saturdays October 26 and November 2. You can sign up through Newton Community Education here.