Taking stock

 It’s been a strange year in my garden. Dogs have completely changed the look and feel of the place. Now I’m about to leave for almost four weeks away, which means I’ll miss much of the fall flowers and foliage color. Before I go, it’s time to assess progress toward this year’s gardening goals.

 

I'm delighted to be growing spotted bee balm at last

 
    This was the year of fencing for my yard. I had to enclose new plantings in wire fencing to keep dogs from digging up the new plants. Older perennials also needed protection in spots the dogs targeted for digging (maybe places where they detected the scent or sound of chipmunks underground?). 

 

Using fencing to deter digging dogs

 

I laid fencing flat on top of the mulch and tacked it down with earth staples. Although I had some unpleasant surprises when the dogs overcame my defenses, over all the fencing worked pretty well. Unfenced areas are another story—lots of groundcover was lost to thundering dog feet.

    My most successful project was a new perennial bed planted into sheet composting. I’d let the mix of leaves and wood chips decompose for two years, helped along by some compost to introduce helpful soil organisms and blood meal to give the organisms a nitrogen boost. This year I reaped the benefits: black, rich soil for planting (mostly) native perennials that could thrive in part shade.

 

Echinacea, heuchera and penstemon getting established in the new bed

 
    Across from them I again planted cutting flowers inside an enclosure backed up against the rabbit fence that defends the vegetable and insectary beds. I chose tall dahlias that I could pick without opening the fence. Getting inside is awkward because the two small beds have no gates; the ends of the fencing are secured to metal posts with twists of wire. Since September, the dahlias have been producing lots of flowers for the flamboyant bouquets I’d envisioned. 

 

Enjoying flowers indoors

Zinnias and celosias in the same bed have been less productive, probably because they’re overshadowed by the towering dahlia foliage. Next year I’m going to try growing zinnias in pots on the deck, where they’ll get lots of sun.

    The beds around the deck haven’t filled in as fast as I hoped when I planted them four summers ago. They got too much shade. There’s still plenty of leaf mulch visible. In fall it’s gratifying to see expanding goldenrods covered with flowers and drawing attention from bees. 

Goldenrod-if you plant it, they will come

 

Asters in the next bed complete the pollinator buffet.

 

New England asters are great for pollinators too

    Around the garden pond I planted several pollinator plants in spring 2020, picturing bulky native perennials attracting crowds of native insects. So far that’s been mostly a bust. Only three species have survived. This year mountain mint (Pycnanthemum muticum) and wild bergamot (Monarda fistulosa) both sprawled inelegantly. 

 

Insects like mountain mint's odd green flowers

 

False aster (Boltonia asteroides), in contrast, shot straight up, producing one spindly stalk. Dry spells, lack of diligent watering, and frequent dog traffic are probably to blame for the others’ attrition. Next spring I’ll pinch the established plants frequently to keep them upright, fill the empty spots with more drought-tolerant selections—and protect the new plants with fencing.

 

A self-seeding volunteer aster is doing more for pollinators than any of my choices. Maybe native large leaf aster?

 

Protecting pollinators

There’s good and bad news about neonicotinoid pesticides during this spring’s plant shopping season. A Vanderbilt study that exposed honey bees to low doses of neonics found that after three days, the bees were sleeping half as long as normal. That’s bad news, because sleep-deprived bees have trouble finding their way back to the hive and may starve and die. 

Neonic-exposed sleep-deprived bees can't navigate

    Bees memorize visual cues for short flights, but when they’re farther from the hive, they navigate by using their circadian clock and their position in relation to the sun. Neonics disrupt bees’ circadian rhythms and throw off this navigation process.

    We seem to be accumulating more and more evidence that these pesticides harm pollinators, but the Environmental Protection Agency still hasn’t made up its mind to ban them or restrict their use, as the European Union has done. A ruling is due this year.

    As I made my plant shopping lists, I had to decide again whether to buy from my favorite garden centers. Could I trust them not to sell neonic-treated plants? I got some good news from two sources. A nearby farm stand with a large garden shop told me that most of their seedlings are started on site, and they don’t use neonics. They’ve switched to biological controls. This opens up a good source for common annuals I buy every year, such as lobelias, marigolds, alyssum, and coleus.

Pollinator-friendly marigolds and Mexican sunflowers, neonic-free

    Jack Russell, the owner of Russell’s Garden Center in nearby Wayland, called back in response to my inquiry about whether plant offerings at Russell’s are neonic-treated. I was relieved to hear his qualified no. Jack said their vegetable plants are neonic-free. For perennials and annuals, he said, they try not to sell anything treated with neonics. 

    The problem for Russell’s and other garden centers is the number of stops plants make on their way to market. Russell’s can certify that their suppliers aren’t using the insecticides, but they can’t be sure that seedlings or seeds weren’t treated before they got to those wholesale producers. Unfortunately, neonics persist for years in plant tissues.

Before planting, I want to be sure native moss phlox doesn't carry poisonous neonics

 
    Some of the suppliers whose plants I buy at places like Russell’s have made a strong commitment not to use neonics. Proven Winners, which produces many of my annuals, has vowed not to treat their plants, although they don’t quite admit that neonics harm bees. Most of the herbs offered at garden centers that I frequent are produced organically at Gilbertie’s Herb Gardens in Connecticut, so I know they’re neonic-free.

 
    In general, edible plants are less likely to be treated than ornamentals. Apparently sellers understand that consumers want pesticide-free food, but they’re slower to grasp how concerned we are about poisoning pollinators.

It's a relief to be able to source neonic-free annuals

    The good news is that the retail market is gradually catching up with ecological gardeners’ preferences regarding neonics. I’m delighted to be able to revisit my favorite plant shopping venues. Now if the EPA issues a ban, we’ll really feel sure that our gardens are safe for pollinators.

Alyssum that's safe for pollinators

 

If butterflies lived here, they'd be at home now

By adding native plants to the garden, I hope to attract more native insects. Sure enough, this year we’re seeing regular visits from pollinators and beneficial insects.

    Gardeners tend to categorize insects as leaf-eaters, beneficials, or pollinators. I used to regard leaf-eaters as a scourge. I’ve changed my attitude now that I understand their importance at the base of the food web, just one level up from plants.

Leaf-eaters provide important ecosystem services

    Plants convert the sun’s energy into carbohydrates through photosynthesis. Leaf-eating insects pass that energy on up the chain. So when I see my kohlrabi’s chewed leaves, I try to remember that the larvae of the cabbage white butterfly (Pieris rapae) that did the damage also provided food for birds and other animals that I want around.

Cabbage white larvae found the kohlrabi

    Beneficial insects are the carnivores that eat leaf-eaters and keep their populations in balance. Some of my favorites are damselflies and dragonflies (Odonata). These are top predators of the insect world, capable of grabbing their prey on the wing because they have the ability, unique among insects, to fly in all directions. 

Virtuoso flyers of the insect world

     Many of the insects I thought were dragonflies are really damselflies, close relatives. At rest, damselflies hold their wings along their bodies, whereas dragonfly wings are held perpendicularly. I’m delighted to notice so many of these beneficial insects around the garden. I’m rarely quick enough to snap their photos, but I relish their bright colors, especially the blues and reds. They often perch on fence posts or flower stalks, like hawks surveying their domain for prey. Damselflies particularly like to eat mosquitoes, so they’re doubly welcome.

Blue damselfly-photo NPS

     I’m hoping that our small garden pond is providing good habitat for dragonfly and damselfly nymphs, the developmental stage before the flying adults. The nymphs live in water for months before emerging on shore, breaking open their exoskeletons, and flying away. I want to witness that someday.

     Among pollinators, we’re thrilled to have been adopted by a ruby-throated hummingbird (Archilochus colubris) that feeds on the nectar of trumpet-shaped flowers near the house: trumpet honeysuckle (Lonicera sempervirens) and hummingbird sage (Salvia guaranitica). Hummingbirds are territorial; males will fight to defend their territory. This one seems to have claimed our deck for his own, and I wish him many happy returns from the migration to his winter home in Central America.

Hummingbird feeding on cardinal flower

     Then there are the butterflies. This week I saw more kinds than ever before. Several monarchs (Danaus plexippus) happened by, checking out the swamp milkweed (Asclepias incarnata). 

Swamp milkweed offers a host for monarch larvae

I’m pretty sure I saw a spicebush swallowtail (Papilio troilus), maybe attracted to a new spicebush (Lindera benzoin) that I planted last year. An American lady (Vanessa virginiensis) alighted on a goldenrod whose flowers are just opening. An Eastern tiger swallowtail (Papilio glaucus) wafted high up among the trees.
 

Spicebush swallowtail-photo Katja Schulz

     I’m increasing my offerings of larval host plants for these butterfly species and also multiplying their nectar sources, the native flowering plants that the adults go to for food. Goldenrods, asters, black-eyed Susans, milkweeds, sunflowers—it’s a banquet for nectaring butterflies.

A Long Dash butterfly? also on swamp milkweed

Native plants spreading good cheer

As we enter June with everything blooming, I feel like putting aside serious garden subjects to drink in the garden’s exuberance. So I thought I’d check on some of the native plants I’ve added in the past couple of years and show you how they’re doing.

    This week I was thrilled to see my cross vine (Bignonia capreolata) burst out with its coral, orange, and yellow trumpet-shaped flowers against the garage. I was expecting it to need more time to recover from transplantation and our northern winter. But no, it’s on the move and offering lots of opportunities for pollinators already.

Cross vine is a vigorous grower

    Nearby, a trumpet honeysuckle (Lonicera sempervirens) is covered with flowers. It seems to bloom more generously every year, although its roots are in a dry patch under the house’s eaves and surrounded on three sides by bluestone pavers. The long narrow flowers are popular with hummingbirds as well as insect pollinators.

Trumpet honeysuckle: easy and gorgeous

    Among the native shrubs, Carolina allspice (Calycanthus floridus) is putting on an unexpectedly uninhibited show. I’d planted one in deep shade a few years ago. It flowers, but sparsely. A newcomer added last spring gets much more sun, and it’s responded accordingly. The weird dark red flowers are fascinating, and I know they’re drawing native insects to the yard.

Carolina allspice has distinctive flowers

    Next to it is a flame azalea (Rhododendron calendulaceum) that I moved from where it was languishing in the front yard, struggling to compete with the roots of the Norway maple towering in the curb strip. When I dug the azalea up, I found it had very little root mass, although it had been there for years. Now it’s got more room to expand in looser soil, and it’s already blooming despite the trauma of last year’s transplantation.

I hope this flame azalea will flourish in its new location

    In the same area, a volunteer black cherry tree (Prunus serotina) is growing by leaps and bounds. This spring it’s showing its first flowers. The challenge with this tree will be to keep it and its offspring from taking over, but I’m encouraging it because of its superior wildlife value.

Black cherry hosts many native insects

    Bearberry (Arctostaphylos uva-ursi) is technically a sub-shrub, although it’s only about an inch tall. I chose this woody plant as a groundcover in a new sunny bed in 2018. It didn’t do much for the first year, but now it’s expanding in all directions, sending out branching stems bearing shiny new leaves. I love seeing this plant growing wild on Cape Cod, and I hope it will spread out even more as a lovely background to taller perennials.

Bearberry likes sandy soil and sun

    In a shadier section of the same bed, a single young creeping phlox (Phlox stolonifera) has emerged and flowered. I recently saw creeping phlox recommended as a groundcover in a Boston Globe story about lawn alternatives. My goal is to see this bed carpeted with a tapestry of groundcovers, so that no mulch is showing. That won’t happen soon, but the creeping phlox’s survival is a good sign.

Creeping phlox getting ready to creep

    Why are these plants doing so well this year? I don’t know, but I’m glad.

Putting the toothpaste back in the tube

At a time when we’re wondering whether what’s broken can ever be fixed, it’s nice to hear some good news about planting for pollinators. A team of scientists in Munich recently published results of their study of urban flower strips, 1,000-square-meter wildflower gardens planted in the city as part of the European Union’s initiative to improve foraging opportunities for bees and other flower-visiting insects. They found these plantings surprisingly effective.

Urban flower strip, Fockenstinstrasse, Munich

    The team undertook their study when the flower strips, sown with a mix of locally native flowering plants, were only a year old. They hypothesized that these mini-meadows would draw mostly bees that are common in Munich and can gather pollen from a broad range of flowers. They didn’t expect these beds to be much of a resource for oligolectic bees, ones that need food from a few native plants. They got a surprise. 

Dogwood andrena bee specializes on dogwood flowers-photo Beatriz Moisset

    In the first year, 61 percent of the bee species known to live in Munich found the flower strips. Most were the common polylectic types, the bees that aren’t picky foragers. But the proportion of specialist  bees that needed particular flowers was nearly the same as in Munich's general insect population. They also found that the urban flower strips increased bee populations in surrounding areas, as far as 1500 meters away.

European dark bee-photo SJ Richards

    By the way, were any bees killed in the process? I was glad to hear that this was a catch and release program. The scientists swept the air with insect nets, put the bees on ice for 10 minutes, and when the bees entered “cold rigor,” they measured and photographed them on site. Within two to three minutes, when the bees had warmed up and awakened, they released them to continue foraging.

    As I prepare to plant native perennials to attract pollinators, this study gives me confidence that my efforts can be effective. Germany’s situation is a lot like ours. The scientists noted that Germany had lost about 10 percent of its meadows between 1991 and 2019. We too are losing open space at a great rate, estimated by the US Forest Service at 6,000 acres every day, or 4 acres per minute. 

Goldenrod provides insect forage in a Maine meadow

     What’s left may be so altered by human activity that it doesn’t offer much of what native insects need. We know that insect populations are plunging. Our government lags behind the European Union’s in addressing this. That’s why there’s such an urgent need for home gardeners to plant for flower-visiting insects.

Pollinator garden at the Smithsonian's National Museum of Natural History

    But can we really replace the rich biodiversity of what’s lost?  I worry that my small effort will offer too little too late. This study suggests that our pollinator gardens can make a meaningful contribution toward rehabilitating impoverished landscapes. I’m hoping my new bed of native pollinator plants will be attractive and full of insect life. It would be nice if it also drew not just the toughest survivors, but also the insect species that need the most help.

Spotted beebalm in my pollinator bed should support native insects-photo Judy Gallagher

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.

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

Love is not love which alters when it alteration finds

In 340 B.C., Aristotle noticed that honey bees tend to choose just one flower species during a foraging flight. This behavior, termed flower constancy, continues to puzzle scientists today. Why, when they could select other nearby flowers that are more “rewarding”—offer more nectar—do honey bees, bumble bees, and some butterflies visit only one kind of flower per trip?

Honey bee on camas flower-photo Victor Berthelsdorf

    Flower constancy works out well for flowering plants. Pollen sticks to the bodies of bees and other pollinators as they collect nectar. If the plant is lucky, some of that pollen will be deposited on a flower from the same species. A bee that visits only one flower species per trip is more likely to deposit the right pollen on the next flower, enabling it produce seeds. A fickle insect flitting between different kinds of flowers may just clog the (female) stigma with irrelevant (male) pollen from other species. That explains how flower constancy helps plants. It doesn’t explain what’s in it for the insects.

Does visiting just one flower type help the bee?

    Scientists have come at this from several directions. One theory is that bees don’t have enough short-term memory to retain a schema of more than one flower to visit at a time. Another is that it’s too risky to invest time and cognitive energy into learning to find the nectar in another kind of flower; better to stick with a flower type that the bee knows will provide a good nectar supply. A third hypothesis is that social honey bees avoid conflict with sister bees from their hive by sticking to one kind of flower and leaving the rest for others to visit. 

Honey bees in the hive with their queen-photo Levi Asay

There are problems with each of these theories and a lack of data to support any of them. Bees aren’t as rigid as some of these discussions imply. They’ve been shown to adjust their flower choices when there’s a really juicy high-nectar alternative.

    On Valentine’s Day, I’d like to believe that flower constancy is actually intentional faithfulness. My husband Steve brings me pollen (actually, a whole bouquet of beautiful flowers) every year at this time. He hasn’t gotten sidetracked yet by any high-nectar cuties.

Received for Valentines Day. Bees, eat your hearts out!

    What do we really know about the inner life of bees? Do they have aesthetic tastes in flowers? Do they have other things to think about while they’re sipping nectar and bringing home pollen for their queen’s offspring? In the bee world, females do the work of transporting floral offerings. The males are lounging around the Drones Club between fulfilling their reproductive role.

Drone bee-photo Epgui

    A worker bee only lives for three to six weeks, during which all her labor goes toward the collective good. She’s not going to mate or have children. Maybe she feels alienated at the hive and happiest when she’s out in the sunlight landing on particular flower petals. She could add variety to her trip with a mixture of blooms, but she doesn’t.

Worker bee making her own choices

    Let’s give her some credit for making a strong positive choice. Why just one kind of flower? Because that’s what she wants.