Bare root planting in a dog's backyard

My native perennials arrived from Prairie Moon Nursery in Minnesota. My reason for shopping at this distant site was the chance to buy plants in bare root form. They’re harvested before the perennials send up shoots for spring, packed in peat moss, and shipped with much less plastic than usually accompanies mail order perennials.

False aster roots ready to plant

    I’m still expecting to receive most of my new pollinator plants from Garden in the Woods, the native plant center in nearby Framingham. I’ll need an appointment to pick up my plants with appropriate social distancing, and I’m still waiting to hear when that will be. These locally native plants won’t be bare root, but they’ll come with a low carbon cost for transportation.

    Garden in the Woods didn’t offer false aster (Boltonia asteroides), though, which is why I connected with Prairie Moon. Once I was on their website, I was intrigued by other native perennials they offered and expanded my order.

One of the intriguing natives was early meadow rue (Thalictrum dioicum)-photo

Tom Potterfield

    The plants arrived as plump packages of peat moss in thin plastic bags. 

Minimal plastic involved

Each species was packed in just one bag: five wild strawberries (Fragaria virginiana) were together in one package. Several of the labels included a diagram showing how deep to set the bare root plant in the ground. I was surprised to learn, for example, that the apparent crown of a early meadow rue was to be buried an inch beneath the soil surface.

Planting instructions

    On a sunny afternoon, I identified the planting sites and surveyed my defensive materials. I was looking forward to seeing the roots develop into young perennials, but that wouldn’t happen if our puppy dug them out of their holes. Fortunately I had a leftover roll of chicken wire and another of hardware cloth—wire fencing with half-inch openings.

    First I tucked the false aster into its prepared spot next to the garden pond. It should be safe inside the fencing enclosure I’d built for it last week. I watered it well and wished it success.

False aster as safe as I could make it

Next I planted the coralberry (Symphoricarpos orbiculatus) near the back fence where this vigorously spreading shrub will have room to expand. I surrounded it with a ring of hardware cloth wired to two metal stakes. If that doesn’t protect it, I’m out of ideas.

Coralberry in a wire cage

    The remaining perennials needed a different approach.  White trout lily (Erythronium albidum) I planted in a moist, shady spot near the bird bath, covering the planting area with chicken wire. I anchored the chicken wire with sturdy two-pronged earth staples and attempted to disguise it with a layer of pine needles (Visual camouflage probably doesn’t fool dogs, I know). 

If white trout lilies survive, they'll be glorious-photo Fritz Flohr Reynolds

I gave the same treatment to a section of a bed off the deck, where I planted the wild strawberries and three wild geraniums (Geranium maculatum). There I tried for extra security by sliding the edge of the chicken wire under a bluestone paver I use as a stepping stone.

Wild geranium-photo David J. Stang

    Now I’m waiting to see whether my arrangements are dog-proof. Here’s hoping!

Digging shallow

This week I skimmed off some more lawn, this time to make space for new sun-loving pollinator plants. I ordered the plants last fall, including a false aster (Boltonia asteroides) and a northern blazing star (Liatris novae-angliae) for this particular spot.

Boltonia should flower profusely in August and September

    When I last visited this topic, I was despairing of being able to plant this year because of the depredations of our puppy, Lola. Fortunately, her daycare has reopened to all comers, so I’ll have some Lola-free days for gardening. That will make this project a lot easier and less aggravating.

    The planting area I’d chosen surrounds our little garden pond. The pond is an artificial creation, an 800-gallon black molded plastic tub sunk into the ground within a circle of lawn in one of the sunniest parts of the garden. When the pond was installed in 1997, the contractor edged it with bluestone. He also set randomly placed bluestone squares and rectangles into the lawn around the perimeter. 

Bluestone around the pond before sod was laid down to make the lawn in 1997

I’ve always liked the pattern he created, but now those stones are taking up space I want to use for attracting native insects.

    I used a crowbar to pry up three stones at one corner, between a spreading Japanese maple (Acer palmatum) and a dwarf Colorado blue spruce (Picea pungens ‘Globosa’). 

Then I carved away the sparse grass—mostly moss—that had grown around the stones and trundled it to the compost pile in the wheelbarrow.

Clods of grass and soil will make good compost

    The soil in this area is quite sandy. There’s a temptation to turn it and dig in soil amendments such as compost and composted cow manure to give the new plants’ roots a soft, cushy bed. I’m holding myself back, though.

    Scientific testing has proved the conventional wisdom about “improving” the soil before planting to be wrong and counter-productive. If I turn the soil, I’ll disrupt the top few inches where most of the biological activity takes place, the soil stratum called the rhizosphere. I’ll break up the architecture created by soil inhabitants such as fungi, bacteria, nematodes, earth worms, and insects. 

Electron micrograph of soil microbes-courtesy of Pacific Northwest National Laboratory

I’ll slow the work they’re doing breaking down organic material into nutrients that my plants’ roots can use. I’ll also bring weed seeds to the surface to germinate, and I’ll introduce a rush of oxygen that will burn through organic material. 

    If I needed to add amendments to this bed, I should use the no-till approach and layer them on top. Soil organisms would incorporate them in their own time. For now, though, I’m not going to try to make rich, ideal garden soil for these native plants. It’s not what they’re used to, and it’s likely to give the advantage to their competitors, such as nonnative weeds.

Why give the weeds a leg up?

    Instead, I just spread the soil that I’d separated from the clumps of grass over the 5-by-5-foot area, covered it with some landscape fabric to discourage weeds until planting time, and surrounded the newly dug area with another hopeful construction of metal posts and wire fencing. Puppy proof? I hope so.

Ready for planting

 

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.