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Sunday, April 5, 2020

Choosing between cultivars

Despite my recent interest in planting straight native plants, I’ve got lots of cultivars in my garden and expect to bring home more in future. Cultivars are improved versions of a species, selected or bred for desirable characteristics such as bigger flowers or new flower colors. Cultivars of native species are sometimes called “nativars.”

This coneflower, Echinacea 'Sundown', is a nativar-photo Mike Peel

    I’m used to thinking that cultivars are selections culled from nursery beds or native plant populations by sharp-eyed growers. But this is only one of the paths to a market-worthy cultivar, I’ve learned. Other cultivars are the products of intentional breeding programs. Once they’ve been found or developed, cultivars will be propagated asexually, through cuttings or divisions, so that the offspring will be exactly like the parent. That means they won’t add genetic diversity to your landscape, as native species will.

    At a recent garden club meeting, a member asked me whether her white-flowered coneflower cultivar counts as a native for the purpose of attracting desirable insects. It’s an important question and an area of active research. Recording native pollinator visits to flowering phlox plants, both straight natives and cultivars, Keith Nevison, a researcher at Mt. Cuba Center in Delaware, was surprised to find that a cultivar, Phlox paniculata ‘Jeana’, attracted the most pollinators. He hypothesized that this might be because ‘Jeana’ blooms so generously and has small, shallow flowers that are easy for pollinators to use.

Tiger swallowtail on Phlox 'Jeana'-photo Michele Dorsey Walfred

    Similarly, the Nativars Research Project of the Chicago Botanic Garden used citizen scientist observations through project Budburst to determine that cultivars vary widely in their attractiveness to pollinators. Among beardtongues (Penstemon digitalis), for example, popular cultivars ‘Husker Red’ and ‘Blackbeard’, loved for their deep purple foliage, drew far fewer insects than ‘Pocahontas’. 

Penstemon 'Pocahontas' at Bluestone Perennials

Scientists suggest that the difference is in the origin of the plants. ‘Pocahontas’ was discovered in the wild. That’s something it has in common with Phlox ‘Jeana’, which was found growing wild outside Nashville. Apparently when plants change in the wild, the new genetic mixes that survive are the ones that cooperate successfully with local insects.

    Some early guidelines seem to be developing for gardeners who want to pick plants to benefit pollinators. Cultivar flowers that resemble the native’s most closely are more likely to attract insects than blooms that have been radically altered in the breeding process.

Echinacea 'Razzmatazz' is probably too different from its straight native ancestor

And now we can surmise that wild-selected cultivars are also more likely to be popular with pollinators than cultivars produced by human breeding efforts. Much more research will be needed before we can be sure which cultivars to plant for pollinators.

    So what about that white-flowered coneflower? Where did it come from? I see that Echinacea ‘White Swan’ may have been introduced by Piet Oudolf, the legendary Dutch garden designer. Did he find it growing in his garden? I can’t tell.

Piet Oudolf border, Royal Horticultural Society Garden Wisley, with white coneflower bottom right-photo Esther Westerveld

    Growers introduce lots of new cultivars of native plants every year. Right now, I think the only way we can determine which ones are most popular with pollinators is to plant them and observe.

Sunday, March 29, 2020

Can't we get along?

This week has been warm enough for some early garden activity. I got to work creating a new bed for cutting flowers. I hope this project can produce blooms this year. 

Wouldn't it be nice?

That can only happen, though, if I can keep my puppy out of their growing area.

    To protect the new bed, I bought some wire fencing and metal posts. Right now, Lola finds newly turned soil so inviting that she has to join in with digging of her own. Maybe next year she’ll have developed some impulse control.

    Setting up the new bed would be easier if I could do it when Lola wasn’t at home. She usually attends day care three days per week to socialize. She was there on Monday, and I took the opportunity to start work on the bed.

    I measured 3 feet out from the vegetable garden fence and drove in three metal posts in a line parallel to the fence. I shaved off the turf in the defined area with my spade. 

Stripping off the grass was the hard part

I moved the grass and the soil clinging to its roots to an empty compost bin. Next I spread some composted manure on the newly exposed soil. I loaded the wheelbarrow with compost and covered the manure with a 3- or 4-inch layer. 

    I wrestled the roll of fencing out to the bed and strung a line of it along the perimeter of the new bed, attaching it to the vegetable bed’s fence posts at each end. 

Fenced in, with amendments layered on the soil

This wasn’t an ideal solution, because I hadn’t created a gate. At planting time, I’d have to roll back the fencing to get access to the soil. But I walked away imagining that I’d barred Lola from the newly dug area. Not so.

    The next day I was incensed to find she’d been digging along the new fence line. Apparently my fence posts weren’t close enough to prevent her from pushing the wire fencing inward and getting some good traction to throw the compost around. Grumbling, I drove in some stakes between the posts to hold the fence more firmly in place.


    On Monday evening, we got the word that the day care program was closing to all but the dogs of essential employees. Everyone else is staying at home to prevent the spread of coronavirus, so we’re not supposed to need doggie day care. I saw my spring gardening plans evaporating. Those dog-free days with time to work outside undisturbed would not be happening. For a while, I thought I might need to make this a non-planting year while I wait for Lola to grow up. 

No future for my flower seedlings?

That would make it really hard to tolerate the stay-at-home advisory, but I’d spend less time mad at my puppy.

    By Saturday, I’d decided to try coexistence. I dug out the turf for the second half of the cutting bed, and Lola mostly heeded my warnings not to dig there. Can we both get what we want? We’ll see.

"Lola, no digging!"

Sunday, March 22, 2020

Hopes for spring

Dear readers,

I hope you're well and bearing up as well as possible at home under the daily onslaught of coronavirus news. I’m going to keep writing about gardening, because I hope it can be a solace during this difficult time.

Glory of the snow is opening this week

    So, happy spring! In addition to starting a cutting garden and siting new native pollinator plants around the garden pond, I’m planning to shoehorn two new native flowering shrubs into the garden this spring: buttonbush (Cephalanthus occidentalis) and coralberry (Symphoricarpos orbiculatus).

    I’ve been wanting to try both of these shrubs for a while now. They keep showing up on lists of native plants valuable to wildlife. Buttonbush, according to the Missouri Botanical Garden’s Plant Finder app, has June flowers that are “very attractive to hummingbirds, butterflies, and other insect pollinators.” The common name comes from the globe-shaped flower heads, which are distinctive and adorable. Long styles extend from the petals, making the flower head look ready for space travel (The style is the stalk that connects a flower’s ovary to the stigma, the part that receives pollen; together the three make up the pistil).

Doesn't this buttonbush flower head look like it belongs on the Jetsons?-photo Jim Evans

    I got my little buttonbush from the plant swap run by our local plant conservation society, Native Plant Trust. Last September, when the Trust’s director of horticulture checked the offerings, he separated local ecotypes—native plants that grow naturally in our area—from North American natives from farther away. I was embarrassed to see that some of the perennials I’d contributed didn’t fit into this most desirable group.

    Even so, I got to take home some choice plants from other members’ gardens, including the 4-inch buttonbush in its little pot. It’s not showing any leaf buds yet, but buttonbush reportedly leafs out late in spring.

    If this buttonbush proves viable, I’ll need to plant it in relatively wet soil, which is scarce in my yard. The best spot would be the lowest lying area opposite the vegetable beds, where water pools when I drain the fish pond. Buttonbush needs at least part sun, so I’ll site it as far as possible from the shade of nearby evergreens. It can grow to 12 feet high. It may be a good choice for screening the recently installed chain-link fence.

A possible space for a buttonbush

    Coralberry, on the other hand, needs room to run. It’s described as a “dense, suckering” shrub that “spreads by runners to form impenetrable thickets in the wild” and does well in “open woodland areas where it can be allowed to spread.” 

Coralberry loaded with fruit-photo Severnjc

That sounds like the area in the back corner of the yard where we took down a big hemlock. There’s a steep slope down to the back fence where coralberry could have plenty of space. I’ve ordered a bareroot plant to set in this spring. 

Buying bareroot avoids the plastic pot-photo from Gardening Know How

I’m looking forward to seeing it covered with coral-red berries. If all goes well, that corner could be a bird paradise in a few years. By then, I hope I can invite guests over to see it.

Stay strong!

Sunday, March 15, 2020

Native flowers for early spring

The flowers that I think of as my spring bulbs are emerging early this year, so much so that it’s worrisome. I’m afraid their blooms will be prematurely cut down by a March snowstorm. 

Crocuses flowering earlier than usual

It’s always heartening to see these first snowdrops and crocuses. They signal that spring is on the way, and they’re important to the first pollinators circulating during these early weeks. I haven’t seen any bees on the crocuses yet, but I’m expecting them soon.

    As lovely as these flowers are, they’re imports. Are there native options?

    Research into what are generally called bulbs always bumps up against botanical correctness. Plants that grow from underground storage organs can correctly be called geophytes, and true bulbs are only one of their adaptations. Others are corms, tubers and rhizomes. Bulbs, as exemplified by onions, are made up of layers of embryonic leaves separated by membranes. 

The layers of an onion are future leaves-photo Amada44

A corm is an upright thickened underground stem, whereas a rhizome is a thickened horizontal underground stem. A tuber such as a potato develops at the tip of a rhizome.

Bearded iris rhizome, Book of Gardening 1900

    Terminology aside, the native range of many of my early bloomers is eastern Europe or western Russia. I’d like to grow more native spring-blooming geophytes, not just imports from the Caucasus.

    While I practice social distancing, I’ve had time to review the early-spring-flowering natives on my plant list. Instead of bulbs, I’ve regarded these geophytes as spring ephemerals. They’re woodland plants adapted to bloom and produce foliage in earliest spring before shade from the tree canopy sets in, then drop their leaves and draw on stored energy to survive the summer.

    Bloodroot (Sanguinaria canadensis) and Virginia bluebells (Mertensia virginica) both grow from rhizomes and flower early and beautifully in my yard.

Bloodroot's early spring flowers

 They’re both happy in their shady locations and forming expanding colonies. 

Virginia bluebells about to open

White trillium (Trillium grandiflorum), another native, also grows from rhizomes. I’ve tried to establish this plant over the years with little success. At present, just one is hanging on along the back fence. We’ll see how it’ll respond to increased sunlight from the switch from a stockade fence to chain-link.

White trillium-photo СССР

    I planted large camas (Camassia leichtlinii), a true bulb, because it tolerates shade. This camas is native to western North America, but there’s another called wild hyacinth (Camassia scilloides) that grows in the East too, looks pretty, and blooms in April and May. Worth a try.

Wild hyacinth-photo Tom Potterfield

    I’m delighted with the yellow trout-lilies (Erythronium americanum), also eastern natives, true bulbs that seem to have established themselves in light shade next to the bird bath and flower in early spring. 

Yellow trout-lily

I could branch out to another native in the genus, white dog-tooth violet (E. albidum).

White dog-tooth violet

    I love white bleeding heart (Lamprocapnos spectabilis ‘Alba’), a tuber former that’s spread around the garden by self-seeding and blooms in May. It’s not a native, but it has native cousins including fringed bleeding heart (Dicentra eximia), Dutchman’s breeches (D. cucullaria), and squirrel corn (D. canadensis) that also flower in early spring in shady woodlands. More shopping opportunities.

Dutchman's breeches-photo Tom Potterfield

Sunday, March 8, 2020

Gardening with Lenore

On Sunday we lost my mother-in-law, Lenore. As the family gathers to recall the good times we shared with this ebullient spirit, I’m remembering Lenore as a gardening accomplice.

Lenore and Norm before their grandparenting phase

    When Lenore’s sons started getting married, she and her husband Norm chose a country house that would be grandchild-friendly. It had a washer and dryer, lots of bedrooms, a big open kitchen, and, as a bonus, a large fenced garden with a water line installed by previous owners. Now that I’m hoping for grandchildren, I admire their strategy.

The vast area fenced for a garden

    I was warmly welcomed into the family as their son’s girlfriend, and we spent many summer weekends at the new house. I was excited about the gardening possibilities. Lenore liked the idea of fresh vegetables, but she was less confident about growing them. She had not-so-fond memories of enforced weeding sessions in the hot sun. Her father, who rode the commuter rail from Westchester to his office in New York City, enjoyed cultivating a big vegetable garden during his time off. He conscripted his two daughters for the grunt work.

Not Lenore, but this must have been how it felt

    I, on the other hand, was over-confident. I was sure that on weekend visits, we could fill the large space, perhaps 80 by 100 feet, with vegetables of all kinds and reap a bountiful and delicious harvest. I diagrammed 12 beds, each 10 by 10 feet, and started ordering seeds. I even sent away for asparagus starts. Lenore, always game, was willing to go along. When May came, we visited the garden center together and filled a cart with seedlings: lettuce, herbs, tomatoes, peppers, eggplants. I remember Lenore commenting to the cashier that the young lettuces were so beautiful, we could just eat them and skip the planting.

    My dad lent us his rototiller, and we used it to prepare our new beds for planting. 

My sister-in-law Liza contemplates the rototiller

Lenore and I chatted happily as we worked side by side along the furrows. I knew she was smart, beautiful and funny. Working with her in the garden, I learned that she was also loving, playful, and generous. By June, we had our seeds and seedlings in the ground and sat back expecting great things.

How we imagined our seedling rows

    If you’ve ever bitten off more than you can chew in the garden, you know what came next. The first year we did harvest quite a lot of vegetables. We learned that weeding was indeed a hard job, despite the mulch I insisted on spreading, and that raccoons knew better than we did when our corn was ready to eat. My attempts at pickling our excess harvest fell flat, but Lenore didn’t criticize. By the third summer, my energy was flagging. I’d provided Norm and Lenore with their first grandchild. Our attention was focused more on him than on the garden.

Lenore enjoying her grandson

    I still appreciate Lenore’s companionship in that vegetable garden. Yes, the plan was far too ambitious and doomed to fail. One of the things I learned from working with her was that, by marrying Lenore’s son, I’d gain the best mother-in-law ever.

Goodbye, Lenore. You were loved.

Sunday, March 1, 2020

Locally sourced and great

There’s a new pile of wood chips in the driveway. After a heavy wind brought down some big pine branches in the yard, arborist Kevin Newman recommended thinning the crown of our tallest pine. His team left me the resulting chips. 

I'm gradually transferring wood chips from the driveway to the garden

    Now is a great time for spreading wood chip mulch. On warmer days, I’d like to be outside doing something in the garden, but nothing’s growing. That’s when I load up the wheelbarrow with wood chips and trundle around the yard to dump them where they’re needed.

    After working with this mulch for eight years, I’m a huge fan. It’s a sustainable choice, because the chips originate in my own yard or nearby where Kevin’s men are pruning or taking down trees. The chips are easy to work with, much less dense than bark mulch. 

A wheelbarrow full of wood chips isn't too heavy to maneuver

Unlike bark, they don’t contain wax, so they don’t block water from soaking into the soil. The first time I dug into the soil under the wood chip mulch, I was amazed. It’s dark, moist and rich—just what a gardener hopes for.

    This year I’m spreading wood chips around trees and shrubs, and I plan to add some to the garden paths, where they break down fastest because of heavy foot traffic. If I do more sheet composting, they’ll be a key ingredient.

Sheet composting March 2019: wood chips on top of composted cow manure

    My source of mulch information is Linda Chalker Scott, a horticulturist and mulch scholar at Washington State University. She corrects conventional wisdom with scientific fact. For example, people worry that wood chips will acidify soil. Research shows they don’t. I’m increasingly aware that soil is not an inert substance. It’s full of biological and chemical activity, including an effective buffering system. You can’t change the pH of soil without adding chemicals such as lime to make it more alkaline or sulfur to make it more acid.

    There’s a gardening legend that high carbon mulch such as wood chips depletes nitrogen in the soil. Linda studied this and found no evidence for it. She hypothesizes that there’s a narrow band of relative nitrogen deficiency at the interface between the soil and the wood chip mulch. This is actually a plus, because it suppresses weeds. You can use this mulch anywhere in the garden except where you’re going to plant seeds or young annuals that don’t have an established root system. Like young weeds, they’d suffer in this nitrogen-poor zone.

Wood chip mulch will suppress weeds around this tree

    Can chips from diseased trees infect your yard? This is a concern I often hear from garden club members. It turns out not, because the disease organisms in mulch can’t reach plant roots. I often see impressive networks of white fungal hyphae among the chips, either in the pile or after they’ve been on the ground for a while. Linda Chalker Scott explains that these fungi are decomposers, not pathogens. With their help, wood chips decompose slowly, gradually releasing nutrients our plants’ roots can use. I’m grateful to have this free material for pampering my plants and soil.

Sunday, February 23, 2020

Just because they're pretty

To grow less lawn, I’m thinking of adding a bed of cutting flowers outside the fenced-in vegetable garden. This spot gets sun much of the day. By reducing the area of lawn between the fence and the bed surrounding an expanding dawn redwood (Metasequoia glyptostroboides) to a 10-foot-wide walkway, I can carve out a 3-foot-deep stretch for cutting flowers.

There's room for a bed of cutting flowers in front of this fence

    This will be backsliding, because the flowers I’m thinking of including aren’t Northeast natives. Zinnias, dahlias, and globe amaranth (Gomphrena globosa) are all native to Central America. I’d also include celosias, from tropical areas in Africa and South America.

Zinnias make reliable cut flowers for me

    For cutting, I’m looking for flowers that last for several days after they’re picked. A couple of summers ago I tried subscribing for a flower share through our community supported agriculture. I found that the flowers didn’t last as long as blooms I picked at home, possibly because of stressful conditions during their trip from the field to the pick-up location.

Globe amaranth should work as a cutting flower

    Perhaps unsurprisingly, there’s lots of lore online from florists about how to extend vase life. Boiling it down, it seems that cut flowers need water to keep their tissues turgid, sugar to allow continued metabolism, and a germicide such as bleach to slow decomposition. Acidifying the water reportedly also helps; one source suggests adding citric acid-based soda such as 7-Up or Sprite for this purpose. 

    The farm and garden at University of California at Santa Cruz offers advice on the harvesting process, from cutting your flowers in the early morning when their tissues are full of water, to recognizing the right degree of flower opening, to when to plunge stems in warm versus cold water. They recommend flowers with thick stems and correspondingly thick xylem cells (water conductors) for longest life, fortunately including the dahlias I plan to enjoy.

Dahlias come in several elegant forms-photo Bernard Spragg

    To prepare the soil for this new use, I could start another sheet composting project. Over the summer, decomposition seems to have proceeded in the one I built last March from layers of wood chips and leaves sprinkled with compost. The level of the pile has sunk, and I’m expecting to be able to plant into it in spring 2021. I’d rather not wait two years to plant my cutting flowers, though.

    Maybe I’ll just peel away the lawn grass and layer on some compost and composted cow manure. The resulting soil wouldn’t be as excellent as what I expect from the sheet compost approach, but it’d probably be good enough for the first year. Then next fall I could decide whether more thorough soil improvement is needed. I’ll surround the flower bed with wire fencing to keep my puppy from digging there.

    Meanwhile, I’ve got lots of seeds ready to start. I sowed tiny celosia and globe amaranth seeds in six-packs this week to give them time to grow strong before moving to the new bed around May 15. I’ll start bigger seeds in March and April, shop for dahlia tubers, and hope for beautiful August bouquets.