Non-stop bloom for pollinators

 This year I’ve been faithfully following a new custom, a weekly inventory of what’s blooming in the garden. It’s turned out to be surprisingly satisfying. I do this to find out whether pollinators have flowers to visit in the yard throughout the growing season. It turns out they do, but I’d like to tweak the types of flowers they find. Now nonnatives often dominate.

 

This beautiful ornamental plum blooms early, but it's not a native

 
    For example, in March, witch hazel, crocuses, cornelian cherry (Cornus mas), snowdrops, and vinca bloomed. Those were welcomed by foraging bumblebees emerging from their winter nests in the ground. But none were native plants. 

    At this point, I’m prioritizing natives when I bring in new plants. That’s because I want to support biodiversity by providing native insects with what they need: pollen, nectar, and leaves for their larvae to chew, all from the native plants they coevolved with. At each stage of their development, most insects need food from the few plants they’ve evolved to focus on over the millennia. They’re usually not equipped to live off plants from other parts of the world.

 
    The obvious exception to this rule is nectar. On any summer’s day, it’s easy to observe pollinators sipping nectar from nonnative flowers. That’s how butterfly bush (Buddleja spp.) got its 15 minutes of fame. Pollinators do benefit from nectar from a variety of flowers, not just natives.

 

Eastern tiger swallowtail sipping nectar from butterfly bush blooms

 
    By May and early June, when lots is flowering in my yard, there was more of a balance. In addition to nonnative hellebores, daffodils, tulips, and vinca, there was native dwarf crested iris (Iris cristata), chokeberry (Aronia arbutifolia), wild geranium (Geranium maculatum), smooth Solomon’s seal (Polygonum biflorum), and Virginia bluebells (Mertensia virginica).

 

Native dwarf crested iris

 
    On it went through the summer: native Catawba rhododendron (Rhododendron catawbiense), trumpet honeysuckle (Lonicera sempervirens), and mountain laurel (Kalmia latifolia) flowered in June. In July there was native tickseed (Coreopsis verticillata), Stokes’ aster (Stokesia laevis), and mountain mint (Pycnanthemum muticum). In August, native wild senna (Senna hebecarpa), goldenrod (Solidago spp.), phlox, and purple coneflower (Echinacea purpura).
 

Three kinds of native milkweed bloomed in succession, offering special food for caterpillars of monarch butterflies: swamp milkweed (Asclepias incarnata), common milkweed (A. syriaca), and butterfly weed (A. tuberosa). Monarchs need milkweed to reproduce, and I hope my collection helps them on their long migration. 

Swamp milkweed

 

This week I found tickseed and goldenrod blooming along with the first New England asters (Symphyotrichum novae-angliae). 

 

New England aster

It’s not only what I’ve planted. When the native white wood asters (Eurybia divaricata) that pop up everywhere in my yard as volunteers come into bloom later this month, they’ll be the dominant floral resource for weeks.

To increase the proportion of natives blooming to at least 50 percent, I’ll need to add more of some plants that are thriving already. A promising candidate is Phlox paniculata ‘Jeana,’ recommended as a butterfly magnet. As research on the best plants for pollinators expands, we’ll have more guidance on which native plants to choose. Drought is teaching hard lessons on which to avoid.

 

Phlox 'Jeana' survived drought in its first summer here

 

 

Drought again

 Massachusetts is suffering from drought, as expected with climate change, and it’s getting to be a problem for gardeners. As of today, we’ve had just 16.25 inches of precipitation this year, approximately 70 percent of normal.

 

Coming soon to the Northeast? Photo

ctrlaltdileep

 
    Coming off last year’s bountiful summer rain, the spring started with lush growth. A lot of my plants are long-established, and they were able to last through some dry weeks without trouble. Now, as the summer drags on without rain, signs of drought are more evident. The 30-plus-year-old European wild ginger (Asarum europaeum) is curling and wilting. New leaves on a clematis I transplanted last year have turned brown and look ready to drop. Container plants droop between waterings.

    I’m running the sprinkler system to water the areas of the garden where plants aren’t well established. It turns on automatically two nights per week, unless its rain gauge tells it not to. That hasn’t happened often this summer. 

Can't you just see the water evaporating? Not ideal.

 

Irrigation keeps the vegetable garden and new perennials alive. It doesn’t give me a great feeling, though, because I know that using tap water for irrigation has a carbon cost for the energy that goes into purification. Three percent of energy produced in the US goes to water utilities. 

    There are long-term steps to minimize the impact of drought, and I’m working on all of them. First, I reorganized the irrigation schedule to leave out established trees and shrubs. They should be able to survive even a prolonged dry spell without supplemental water. If I had a lawn, I’d let it go brown, but there’s so little lawn left in my yard that not watering it hardly makes a difference. The wood chips that replaced the lawn grass torn up by thundering dog feet help keep the underlying soil from drying out, so that’s a plus.

 

Wood chips and vestigial lawn in June

 
    Along with those wood chips, I’ve let fall leaves lie on some beds and spread chopped leaf mulch on others. Those reduce the need for watering by keeping soil cool and slowing evaporation. Adding organic material to the soil with precious wheelbarrow loads of compost helps our sandy soil retain water too.

 

Compost adds organic matter to soil

 
    My last water conservation measure is a water barrel at one of the downspouts from the house’s gutters. When it rains, the barrel fills and gradually feeds water into a soaker hose that irrigates shrubs at the front of the house. 

 

Storing rainwater is a good idea, but it has to rain

Drought reveals this plan’s weak point: when it doesn’t rain, the water barrel doesn’t fill up. If I ever build a new house, I’ll insist on a gray water system that collects water from the showers, dishwasher and clothes washer for use in the garden. Las Vegas has a well-developed system for reusing gray water that, with other adaptations, allows the city to survive in the desert.

    In the meantime, I might start collecting rinse water in the kitchen sink or keeping a bucket in the shower to catch a few gallons for use outdoors. Desperate times call for desperate measures.
 

It's not too late

Could you use some good news? Here’s some: last Thanksgiving the population of Western monarch butterflies counted in California increased by over 100-fold, from fewer than 2,000 butterflies counted in 2020 to 247,237 in 2021. 

 

Monarchs roosting for the winter

That’s not full recovery. Some experts estimate we’ve lost 80 percent of monarchs in 20 years. But it’s nice to know how resilient these butterflies can be.

    Western monarchs are genetically indistinguishable from the Eastern kind. It’s just that monarchs that live west of the Rockies overwinter in California and migrate to the Northwest for the summer. The ones that live east of the Rockies overwinter in central Mexico in the Monarch Butterfly Biosphere Reserve. Around this time of year, as the weather warms, they start their flight to Texas.

 

During the spring three or more successive generations of monarchs journey through the Southeast to the northern states and southern Canada where they spend the summer. Then in August and September another new generation starts to flutter all the way back to Mexico, a journey that takes up to two months (this Google Earth video illustrates it all). 

    Migration is necessary because monarchs can’t survive northern winters. In the mild, humid winter climate of Mexico’s Sierra Madre mountains, they roost in oyamel fir trees (here’s another fascinating video), packing together to stay warm. 

     With this successful life cycle evolved over the millennia, why did the monarchs suddenly start to disappear? The first obvious culprit was glyphosate (Roundup) sprayed on agricultural fields. Glyphosate use surged in the 1990s with the introduction of genetically modified Roundup Ready crops that resist the herbicide spray while it kills the weeds around them. 

Monarch caterpillars need to eat milkweed to survive. Milkweed toxins ingested by monarchs make them poisonous to predators but don't hurt the monarchs.

     Some of those weeds/wildflowers are native milkweeds. Monarchs need to lay their eggs on milkweeds to reproduce. Instead of finding milkweeds offering nectar and forage for their caterpillars alongside every field, the migrating butterflies now had to cross vast milkweed deserts in agricultural regions of the U.S.

Eastern native swamp milkweed is easy to grow and provides a lifeline for monarchs

     A recent meta-analysis by a team at Michigan State University, using data from thousands of volunteer monarch counts, found that glyphosate, habitat loss, and climate change have all contributed to the monarchs’ decline. In recent years, hotter weather in their northern range seems to have been a major factor.

     When we hear that climate change is the reason that species are dying out, it can sound hopeless. We’re not moving fast enough to save ourselves; how are we going to save the monarchs? But as the scientists point out, when migrating monarchs are stressed by high temperatures, that’s when they especially need lots of milkweeds and other native flowers for nectar along their path so they can stop off and refuel or lay eggs.

 

Migrating monarchs need other flowers too for energy from nectar

 
     The surge in Western monarchs shows that the monarch population has the capacity to rebound suddenly and dramatically. And the fact that thousands of human well-wishers are already helping encourages me too. This year let’s redouble our efforts to plant for native insects, and let’s be sure to include milkweeds in the mix.

 

Common milkweed is another good choice. It's a spreader.

 

Ecological gardening

 While snow blankets the garden, it’s all potential. Dreaming of spring, I’m enjoying reading about ecological gardening—what I’ve been calling sustainable gardening, but I like the new term better. As Kelly Norris writes in a recent article in Fine Gardening, ecological gardening means understanding plants as part of a community, not just building blocks for an aesthetic composition.

 

Native Joe Pye weed in an ecological garden

    Goals I currently aspire to achieve in my ecological garden include promoting and supporting biodiversity, helping to keep air and water clean, sequestering carbon, minimizing my garden’s carbon footprint, conserving water, and preventing stormwater runoff. Since these are inherent functions of natural systems, the good news is that gardening this way should be less work, not more.

 

Leaf mulch conserves soil moisture and provides shelter for native insects

 
    Native Plant Trust and the Woodwell Climate Research Center have been researching how these goals can be accomplished in suburban yards in their Yard Futures Project. They’ve chosen yards in six cities: Boston, Baltimore, Minneapolis-St. Paul, Phoenix, Los Angeles, and Miami. The lucky chosen ones get a visit from a team that’s prepared to observe and document what’s living on their property, from birds to insects to soil organisms. The goal of the research is to document the current state of backyards in a range of climate conditions and discover how suburban properties can best support a healthy environment.

    I wish my yard had been chosen! I’d love to know what experts could find there. In one visit, they could detect and document far more than I ever will. But I’m hopeful that my yard would show lots of biodiversity, because I’ve been trying to put out the welcome mat with native plants and gardening strategies that imitate natural processes.

 

Virginia bluebells

    To take it up a notch, I can start to think more about how plants weave together in natural settings. For example, when choosing a perennial, I pay attention to whether it’s a spreader. That might be a red flag for a traditional garden, but for creating a ground cover layer in a naturalistic ecological garden, it can be an asset. But I don’t usually ask whether a plant is tap-rooted or rhizomatous, grows singularly or in colonies, is short- or long-lived.

 
     In nature, plants fill every available space, above ground and below, gaining from each other’s contributions and maximizing diversity. Instead of fields of mulch punctuated with separated plants, ecological gardens are a mix of tall and short, broad and upright, early and late-developing plants, similar to what you’d see in a wild setting.

 

Plants knit together in an ecological garden

    This doesn’t have to look like a mess. By maintaining clear edges and growing large swathes of species that flourish in site conditions, ecological gardeners are creating gardens that are “legible”—appealing to viewers as designed spaces.

    So for this spring and summer, I’m thinking about how to fill up beds with more—more low spreaders, more early bloomers for the first pollinators of the year, more self-seeders. They should be native plants, but that’s not all. They should contribute actively to the plant community.

 

For the pollinators

 

 

 

Going peat-free

 I was encouraged to see a recent New York Times story about replacing peat-based potting mix with more sustainable materials. I just wish the writer, Margaret Roach, had gone farther and described her experience with the new materials.

Mer Bleue peat bog in Canada

    Peat has been the dominant ingredient in growing media for a long time because it’s great at absorbing water and nutrients but lets air and water flow through, and it’s slow to decompose. The problem is that peat is not a renewable material, at least on a human time scale. Peat bogs are giant carbon sinks, sequestering more carbon than all the trees in the world. Extracting peat from peat bogs releases carbon dioxide into the atmosphere, contributing to climate change.

    Peat forms very slowly when wetland plants decompose in oxygen-poor water. The peat we garden with took thousands of years to form. As we confront the climate emergency, we need materials for growing plants in containers that come without environmental degradation and a high carbon cost.

    When I learned about peat’s downside, I switched to making my own potting mix by combining sifted homemade compost with coir, or coconut fiber. This mix works just as well for my container plants as the peat-based potting mix I used to buy at the garden center. 

I combine coir and compost to make peat-free potting mix

     To make the volume of potting mix I need, I buy 5-kg compressed bricks of coir from a hydroponic growing outlet or Home Depot. You can also buy big bags of loose coir, but whatever kind you buy, it needs to have been washed to remove salts. To use it, just wet it by soaking in a barrel. Sounds like an easy solution, right? Unfortunately, coir comes with a carbon cost for shipping it here from tropical areas.

 

Container plants flourish in the peat-free mix

 
    From Ms. Roach’s article, I learned that US researchers are working on developing wood-based recipes for potting mix. Ideally, those could be made from local materials. She interviewed Brian Jackson, a professor at North Carolina State University and director of the Horticultural Substrates Laboratory. This is another area where Europe is way ahead of us. They’ve had wood-based growing media on the market for 30 years. Britain is moving toward banning peat in horticultural products.

An example of UK peat-free compost made from bark and wood

 
     Jackson’s team reports best results from a combination of peat and wood. Combining them creates a stable, spongy material that retains water especially well. It’s porous and provides lots of air space, creating an excellent environment for root growth. I’d rather drop the peat from the recipe completely. How about wood fiber combined with compost? That seems to be working in Europe.

     So far, wood fiber for growing plants seems to be available to large-scale growers in the US but not to home gardeners yet. While we wait, I recommend the coir-compost blend. But the best thing we can do as consumers is to ask garden centers to stock peat-free potting mix, whether it's based on coir or wood fiber. Why should Europeans get all the good stuff?

Choosing a successor

This fall I made a difficult decision to cut down two trees that framed the view from the house into the back of the yard. Now I have an opportunity to plant in the space left behind by a crab apple, Malus ‘Donald Wyman,’ that I picked out soon after we moved into the house in 1985. It stood next to our tallest tree, a towering red oak. As you’d predict, that oak proved to be its greatest challenge.

    The crab apple did bloom, more than I had a right to expect after planting it in part shade. It made lovely red buds that opened to white flowers with a delicate apple blossom scent. It produced small red fruits for the squirrels and birds. But over the years, reaching for the sun deformed its shape. Despite annual pruning efforts, it stretched its branches away from the oak. I couldn’t face another winter of being reproached by the misshapen leafless form of this tree.

 

Leaning redbud and twisted crab apple flank the path

    The other tree we cut down was a lovely white-flowering redbud, Cercis canadensis f. alba planted under a tall white pine. It had the same malady as the crab apple. Its shape as it reached for sunlight was uncomfortable to view.

    After a wrenching day when the two old friends were reduced to wood chips, I felt vindicated by the new vista. Instead of viewing the back of the yard through a small opening, we could now see all our trees and enjoy their contrasting textures. 

The new view, November

We’re left to decide what to plant in the open space where the crab apple used to stand.

 

The goose marks the empty spot

    There are numerous criteria. We want something that flowers in spring, so it needs to harmonize with the pink blooms of a nearby ornamental plum. I’d like to choose a New England native, or at least something that’ll be native here soon as the climate warms. I’m looking for a sizeable shrub or a multi-stemmed tree that I can prune myself, so it shouldn’t grow too tall. And it would be nice if it produced fruit to feed local wildlife. It’ll get morning sun but have to cope with the shade of the oak for the rest of the day. A lot of the native shrubs that appeal to me are happiest in a moist location, but they won’t get much moisture in the crab apple’s spot.

    Here are some ideas: 
•    Red and black chokeberry (Aronia arbutifolia or melanocarpa) produce small white flowers and attract birds with their red or black fruits

Red chokeberry 'Brilliantissima'

 
•    American cranberrybush (Viburnum trilobum) has elegant white flowers and red fruit in fall

American cranberrybush

•    Coastal serviceberry (Amelanchier obovalis) blooms early and attracts birds with its fruit

Coastal serviceberry

•    Red osier dogwood (Cornus sericea) has bright red stems that stand out in winter

Red osier dogwood

•    Pink shell and roseshell azalea (Rhododendron vaseyi or pinophylllum) have early pink flowers

Pink shell azalea

•    Pussy willow (Salix discolor) produces pollen when it’s most needed in early spring

Pussy willow-photo Thomas Kent

Which will it be? There’s a long winter ahead for considering the choice.

Leave the leaves

What used to be a far-out, novel idea is now joining the mainstream: “Leave the leaves.” To support biodiversity and especially to provide protection for native insects, gardeners are changing our fall routine. For the past three years, I’ve been letting whole leaves lie on my garden beds.  

 

Whole leaves work as mulch

    This change allows me to do a lot less work. I used to spend many hours in late October and early November raking leaves to a spot at the back of the house where I could plug in my leaf shredder. I’d feed as many leaves as possible into the machine--basically a string trimmer in a drum—to make shredded leaf mulch for my perennials. 

 

Leaf shredder: effective but labor intensive

Now I just gather leaves from the driveway, the sidewalk, and the roadway along our block, rake them onto a tarp, and drag the tarp into the backyard. There I dump the leaves on whatever bed seems to need a blanket of mulch. 

    The concept behind this time-saving approach is that lots of native insects overwinter in fallen leaves, whether as eggs, larvae, nymphs, or adult insects. When I chop up leaves in the shredder, I’m chopping up those insects, reducing next year’s population of native insects in my yard. That’s working against myself, because I need a balanced population of leaf eaters, pollinators, and beneficial insects—the predators that keep leaf eaters in check—to keep my garden ecosystem healthy.

 

I want to host beneficials like this lacewing

 
    While environmentalists and proponents of sustainable gardening advocate for leaving the leaves, I’m disappointed to notice that some of my favorite garden writers are pushing back. I’ve read warnings that a cold-season mat of whole leaves will damage turf grass. Yes, we all knew that! Another worry is that perennials won’t thrive under a blanket of leaves. The thought is that plants from Mediterranean climates may need breathing room and a drier environment.

    All I can say is that these commentators must be gardening very differently than I do. Most of what used to be turf grass in our yard is now covered with wood chips that have no trouble accommodating a layer of fall leaves. And my perennials are ones that have proven tough enough to survive the conditions in the yard—sandy soil, rabbits, varying degrees of shade, humid summers with periods of drought and, increasingly, cold snaps in winter without snow cover for protection. If perennials needed pampering, they’ve long since died out in my garden.

 

Lavender toughs it out in the garden without special treatment

 
    Given my limited perennial-growing ambitions, I’ve had no trouble with leaving the leaves. Increasing numbers of birds visiting the yard suggest we’ve got more native insects than we used to.

    In spring I do like to peel back the matted leaves from the newest perennial bed off the back deck. It’s quick work to dump them in the wheelbarrow and move them to the compost piles. If I’ve got some dry fall leaves in bags in the garage, I’ll shred them at that time to replace the mulch I’m taking away. Moderation in all things.

Dwarf crested iris, another survivor