Being part of the solution

 To meet my environmental goals, I’ve been avoiding peat-based potting mixes and trying to cut down on buying plastic pots. As I plan next year’s garden, I’m thinking about how I can move this campaign up a notch.

Starting to envision spring lettuce

    Now that I know that peat is a non-sustainable resource, I’ve turned to coconut fiber, or coir, as the key ingredient in my seed-starting mix. I can live dangerously and use my homemade potting mix, which is half coir and half sifted compost from my compost bins. That mix isn’t weed-free or sterile. 

Coir and compost mix ready for summer containers

Or I can buy coir-based products such as Organic Mechanics Seed Starting Blend, made of coconut coir, pine bark, rice hulls, and worm castings, with no peat. This mix is pretty easy to find, and it works well for me.

    The next problem is the containers. I’ve got a collection of plastic six-packs for seedlings. Some I bought new—regrettably, I now feel. Others came with seedlings I bought at garden centers. 

 

A lifetime supply of seedling six-packs

I’ve washed and reused these, often through more than one seed-starting cycle. Eventually they tear and have to be discarded. 

    Last year I reached a turning point in my thinking about plastic pots. For years, the “green industry”—the businesses that produce and sell garden plants—have chosen plastic containers for their low cost, durability, and light weight. Now the industry can’t easily pivot to other materials, because they’ve designed their machines around the plastic pots’ sizes, shapes, and other physical properties. If they’d make a start, though, I bet lots of consumers like me would be willing to pay a few extra cents for non-plastic containers.

Even my local native plant shop uses plastic pots

    I was heartened by a recent Fine Gardening article about biocontainers. The writer, University of Georgia professor Bodie Pennisi, describes two types of biodegradable pots: plantable pots made of recycled paper plus or minus dehydrated cow manure, and compostable pots made from pressed coir. 

 

Coir pots

These are relatively durable and neat-looking. A more ephemeral product is a paper sleeve made from wood fibers that lasts long enough to contain flower and vegetable starts.

    Like me, you may have tried starting seeds in flats and pots made of pressed peat. I found these didn’t decompose as advertised. I plan to try starting seedlings in CowPots this year. These are the brainchild of a Connecticut farmer who’s been producing them from homegrown cow manure for 20 years. They’re said to keep their integrity for 12 weeks above ground. After planting, they should break down in one growing season, allowing roots to penetrate easily. The nitrogen in the decomposing cow manure reportedly gives the young plants a boost.

CowPots at Gardener's Supply

 
    For perennial divisions, I’d prefer longer lasting containers. I’m going to try pressed coir pots. I see that I can buy some from Greenhouse Megastore or Gardener's Supply, if not at my local garden center. I’ll report back on how these products work out.

 
    Now, how to do we get the garden industry to make the switch too?

Food for thought

 This week my garden club got together on Zoom to watch a video of a talk by Doug Tallamy. I’ve been a Tallamy follower since 2011, when his book Bringing Nature Home changed my gardening philosophy. Since then I’ve been working on growing more native plants.

 

Insectary bed: flowers and foliage for pollinators and other insects

    In 2019 Tallamy published a new, more prescriptive book, Nature’s Best Hope. He’s marshaling us to rescue biodiversity by creating Homegrown National Park, a combined nationwide habitat for native insects in our backyards. 

    Tallamy demonstrates how we can get the most environmental bang from our native plantings by prioritizing caterpillar host plants. Caterpillars provide the lion’s share of the biomass birds need to feed their young. 

Hummingbirds feeding insects to their chick

Tallamy has identified more than 800 caterpillar species on his 10-acre property in Pennsylvania as he and his wife have replaced nonnative invasive plants with natives (check out his stunning photos of some of them in the new book).

    A light bulb went on for me when Tallamy mentioned that people occasionally write him to point out that an imported species—the Asian ginkgo tree (Ginkgo biloba), for example--used to be native to North America in a previous geological era and claim it’s therefore entitled to native plant status. That doesn’t matter, he said. What’s important is whether a plant supports any native insects. Ginkgoes don’t.

 

Ginkgo is a beautiful tree from Asia-photo Sunroofguy

 
    We’ve come a long way since concern about supporting insects first surfaced. I remember reading in the 1980s about designing a butterfly garden. That was when we planted butterfly bush (Buddleia spp.), which is now out of favor because it’s nonnative and potentially invasive. Butterfly bush and many other flowering imports do serve a purpose, though, providing nectar for bees, butterflies and moths in their adult forms.

Eastern Tiger swallowtail nectaring on a butterfly bush

    As I became more aware of my garden as an ecosystem, I started planting native flowers that provide the right pollen for native pollinators, especially bees. Now we can take the next step and choose to plant for native caterpillars. These aren’t looking for flowers. While adult pollinators can afford to sip nectar unselectively, caterpillars need to eat the right leaves to be able to grow and pupate.

      Because of decades of research in this area, we now know that about 90 percent of insects specialize: they’ve evolved to live off a limited group of plants. Most caterpillars aren’t equipped to deal with the chemical defenses mounted by plant species outside their small group of native host plants.

 

Monarch caterpillars need to eat milkweed

 
    So with data accumulating about which plants host which native insects, we can stop fighting about whether gardeners should plant only native plants. Instead, we can ask which plants host the most insects. Tallamy proposes that we prioritize keystone plants, such as native oaks, willows, cherries, and goldenrods, that provide food for hundreds of species of native caterpillars. How to find these? You can go to the websites of the National Wildlife Federation and the Audubon Society and get lists for your zip code. Somehow this prescription seems much more doable.

 

Native red oak supports more insects than any other local tree-photo Jason Hollinger

 

Oh dear

Wildfires in the West, powerful hurricanes and flooding in the South, and derecho in the Midwest. Meanwhile, the Northeast has been feeling relatively safe. We’ve had a severe drought, but so far climate change hasn’t turned us into refugees. 

    Well, we might not be immune to strange weather events. This Friday saw an unusually early snowstorm that weighed down tree branches still in full leaf. 

Ornamental plum bent low by heavy snow

This happened once before in my memory, in 2011, when a Halloween nor’easter shut down much of the New England. But it’s still far what we expect for the end of October. We’re supposed to be raking leaves and decorating our front steps with pumpkins, not shoveling snow.

    My garden got caught way off guard. All the tender perennials were still in their beds and containers. Now they’re a soggy mess, as is the basil I’d hoped to harvest. 

A pot of herbs. Rosemary made it, basil didn't

 

I wanted to provide blooms for pollinators through November. I don’t know whether the aster flowers will survive after two days coated with heavy snow. 

 

Will these aster blooms last after they thaw?

 
    All I can do is start the process of closing down the garden for winter, though these tasks are coming a lot earlier than I’d expected. When the potting mix thaws, I’ll bag up the elephant ears and cannas and store them in the basement to repot next year. 

 

The canna season has definitely ended

I’d hoped to pick a few more dahlias, but their tubers too will need to be packed away if I hope to replant them in spring. Today the water barrel holds a block of ice. If the weather warms up later in the week as predicted, I’ll empty the barrel and store it in the garage.

    I’m still hoping for some mild days to move compost into newly built raised beds in the vegetable garden. This will be the place for the compost in those aluminum trash barrels I used for food waste, after noticing that fruit and vegetable scraps on the open piles were attracting rodents. 

Composted food waste for the raised beds

If I can’t lift the barrels into the wheelbarrow, at least I can roll them across the yard. That’s the good thing about their cylindrical shape. I’m hoping these contained beds will boost my vegetable harvest. With 3-foot wide beds and 2-foot paths, I won’t walk on the soil around the growing plants, something I couldn’t avoid with my old free-form design. 

Raised beds for vegetables

 
    The other activity for the next month will be relocating fallen leaves from the front of the house to the backyard. Before the snow, I’d fortunately shredded a few for the perennial bed off the deck. There I find finer mulch preferable as new young perennials emerge and gradually expand. 

     For the rest of the yard, I’ll be keeping the leaves whole. Lots is written these days about the advantages of this system. By letting the whole leaves lie undisturbed through the winter, we provide shelter for important native insects that hide there as adults, eggs, or pupae. Plus, it’s a lot less work than bagging or shredding those leaves.

 

 
 

Getting by without rain

In late July I blithely congratulated myself on watering less, assuming that rain would come and my plants would be refreshed without supplemental irrigation. My expectations were way off. In the month of September, we got less than an inch of rain. So far October is just as dry.

The garden is drooping

    During the drought, I’ve had to make difficult decisions about watering. I’m finding out the hard way which plants can tolerate sustained dryness. For container plants, it was easier to know what to expect. In hot weather, they wouldn’t last more than a day or two without watering, because the small volume of growing medium in the pot dries out so fast. Those I kept watering with the hose wand or watering can.

    Then there were newly planted perennials and shrubs. Before the drought, I optimistically planted in new areas. When we replaced a rotting stockade fence with chain link last fall, I planted a row of evergreens. In spring I added a buttonbush (Cephalanthus occidentalis) 

 

The buttonbush has survived so far

and moved a chokeberry (Aronia arbutifolia) to a sunny spot nearby. Around the garden pond, I planted native perennials for pollinators: false aster (Boltonia asteroides), northern blazing star (Liatris novae-angliae), wild bergamot (Monarda fistulosa), and mountain mint (Pycnanthemum muticum). All these will need supplemental watering for their first two years. I’ve kept at it with the watering can.

 

Northern blazing star at the end of its first season

 
    For the rest, it was survival of the fittest. The lawn completely surrendered. With our dog and her friends racing around on its parched surface, the grass wore away completely. Luckily, turf grass is my least favorite garden plant. It should grow in cool, damp environments like the British Isles, where it belongs.

So much for the grass

    In the drought, it’s easy to see the advantage of protective adaptations like waxy leaves. The boxwood (Buxus sempervirens) hasn’t batted an eye. The vinca (Vinca minor) groundcover in the front yard is starting to droop after two full months with no water at all, but it’s still green—another reason I’m glad it replaced the former front lawn.

Vinca has proven very tough

But some waxy leaves of a few evergreen shrubs are turning yellow or brown, as on the Catawba rhododendrons (Rhododendron catawbiense) and mountain laurels (Kalmia latifolia).

 

Rhododendron leaves yellowing

 
    Softer deciduous leaves are drooping. Even the Canadian wild ginger (Asarum canadense), which is usually impervious, has flopped to the ground. 

 

Wild ginger has collapsed

 

In contrast, the goldenrods (Solidago spp.) and asters (Symphiotrichum spp.) are unfazed.

Goldenrod dealing with drought

     I notice that some perennials with fleshy roots have an advantage. Smooth Solomon’s seal (Polygonatum biflorum) is still holding up its leaves. In the cutting garden, the cosmos (Cosmos bipinnatus) has turned completely brown, but dahlias are going strong. Presumably rhizomes and other fat root forms store water for hard times.

 

Smooth Solomon's seal has fleshy roots

 
     I find myself wishing that some of the rain flooding the Gulf Coast would come our way. We’re supposed to get some remnants from Hurricane Delta next week. May it be so! At this point I’ll only believe it when I see it, because so much forecasted rain hasn’t materialized.

 

New England aster holding up well

 
 

A drop to drink

As our area’s drought continues, wildlife has trouble finding water sources. My garden offers several.

 

Birdbaths offer water in dry times

     Back in 1997, we sank a rectangular plastic fish pond in the lawn and edged it with bluestone. A pump oxygenates the water and circulates it through a biological filter. 

The pond in May

For several years I brought home young koi from the garden center to live in the pond, but they all disappeared in a year or two. Some were clearly pulled out and eaten, possibly by raccoons. Half-eaten bodies were left behind. Other fish just weren’t there the next spring.

Koi weren't making it to this size

     I decided I’d assassinated enough koi and stopped restocking. Now the pond just houses water plants, and I’ve switched to hosting tadpoles. It’s fun to see them grow into tiny frogs that like to sit on the stones beside the water, jumping in as footsteps approach. 

 

Frogs are fun, and they eat insects

    Meanwhile, the pond provides drinking water for wildlife ranging from birds to squirrels to our dog Lola, who likes to wade in and pull out floating plants. Birds perch on the netting that covers the pond in winter to keep falling leaves from settling on the bottom. In this way they can walk across the pond to drink, safe from heavier predators.
 

    I’m pleased that toads have taken up residence in the garden, because they’re prodigious insect eaters. Toads are actually a kind of frog, and they too need to start their life cycle as eggs and tadpoles in water, so the toads I’m seeing may have been born in the garden pond.

 

A well-camouflaged toad

 
     Specifically for birds, I maintain other water sources as well. There’s a stone birdbath at the base of a redbud in view of the kitchen windows. The basin kept falling off its pedestal until I built a brick base for it, fearing that some small animal would be crushed. A ceramic birdbath spends the summer under a nearby crabapple. Birds approach cautiously, perching on nearby branches before landing in the water and puffing out their feathers for a wash. 

 

Birds like water near trees or shrubs

  Hanging from a spruce branch at the side of the house is a water bottle with a perch for birds. This one allows them to drink without the danger of landing near the ground.

 

A safe perch for cautious birds

     In the hottest weather, I’ve also put a few inches of water in a child’s wading pool to allow Lola to cool her feet. I notice that birds regard this as another larger birdbath. With all this standing water, I have to be careful not to provide breeding ground for mosquitoes. I empty out the water every two days, and each month I drop Bti (Bacillus thuringiensis subspecies israelensis) into the pond. It’s a safe soil bacterium that kills mosquito larvae.

    Friends, I’ve decided to stop posting on a weekly schedule. I find I’m running out of subjects. I’ll continue posting occasionally when a topic comes to mind. If there’s something you’d like me to write about, please let me know. Thank you for being with me over the years!

 

 

 

A fair exchange

An excellent summary by Anne Bikle in Fine Gardening reminded me that there’s no free lunch in the rhizosphere, the top few inches of soil where most of the biological activity happens. True, lots of soil organisms are at work breaking down organic matter into forms that our plants’ roots can use. 

Electron micrograph of soil microbes-photo Pacific Northwest National Lab

But that’s not a coincidence. The roots offer something in return. Every plant exudes proteins, carbohydrates and fats from its roots. These attract the organisms that help plants get what they need and protect them from diseases and pests.

 

Fungal network associated with spruce roots-photo André-Ph. D. Picard

 
    Bikle’s article was a good reminder to support this process by taking good care of soil organisms in the garden. I checked myself against her three recommendations: leaving soil undisturbed when possible, mulching to add organic material to the system, and growing a variety of plants.

    A few years ago I gave up turning the soil in the vegetable bed with my spade before planting in spring. I’d thought this was a necessary step to mix in amendments such as compost and composted manure and turn under any weeds that had sprouted.

     I stopped all this digging when I learned it was counterproductive. I was breaking up soil networks, killing or slowing down soil organisms that were nourishing my plants. I was also churning through organic material by introducing a rush of oxygen into the soil, wasting the compost I added to the bed. 

     I found out it was better to let soil organisms do their work undisturbed. Now I confine the digging to times when I need a planting hole for a seedling such as a young tomato plant. The soil in the vegetable bed has improved. As a side benefit, I’ve got fewer weeds, because when I cut out the digging, I stopped bringing weed seeds to the surface to germinate.

I avoid digging except to plant seedlings

    I’m also making a point of not clearing away leaves that fall on the ground, except on the lawn. I’m still working on striking a balance for fall leaves. I used to chop them up for leaf mulch, until I learned this also chopped up useful insects at various stages of development that were settling into the leaf litter for the winter. For the past couple of years, I’ve mostly let the leaves lie on beds, supplemented by more leaves I drag in from the street that would otherwise go to the city’s composting site. 

 

Letting fall leaves lie

     

     Now I’m missing my leaf shreds. There are places where they’d be especially useful, such as in the newest perennial beds, where the soil could use some quick help. The leaf shreds stay put, not blowing around like whole leaves, and they decompose faster. This fall I think I’ll do some limited shredding to cover those spots.

 
     From Bikle I learned that I’m offering a diverse buffet of root exudates by increasing variety in the garden as I’ve added native plants. That’s because each plant sends out its own recipe to attract organisms to meet its needs. All the better.

 

A mix of native plants: wild ginger, leucothoe, heuchera

 

Sharing

 At this time of year, the garden starts to look tired and ragged. This week I took the opportunity to reassure myself that chewed leaves aren’t a problem for garden plants. They have lots of ways to deal with chewing insects, and lots of leaves can be chewed without changing a plant’s beauty.

Canadian wild ginger

Humans aren’t that sharp about noticing chewed leaves. Research on aesthetic tolerance has found that 10 percent of the foliage in a garden can be damaged by herbivorous insects before the average gardener even notices.

Insects have been chewing the ginger leaves

     Plants notice, of course, and they’ve evolved a range of tools for turning away hungry animals. First there are mechanical barriers, such as the bark and thorns that some deploy. Without these obvious weapons, though, lots of other plants are ready with chemical defenses.

Closeup shows insect damage

 

Oxeye sunflower

     

 

 

 

 

 

 

     

 

 

We often hear about plants whose tissues are poisonous to leaf-eaters. Milkweeds (Asclepias spp.) can’t be eaten by any but monarch caterpillars because their sap contains toxic cardiac glycosides. Foxgloves (Digitalis spp.) poison browsing herbivores with digitalis in their tissues. 

    Other plants can generate chemical responses to browsing insects. Goldenrod, for example, sends out a chemical signal that keeps leaf beetle larvae from eating too much of each plant. A team at Cornell found that a chewed goldenrod plant sends out volatile organic compounds warning the larvae away from itself and its neighbors. The scientists found that the larvae preferred unchewed plants. 

Goldenrod can communicate with plants and insects

     The goldenrod’s chemical message also alerts nearby goldenrods to the danger so they’ll ready their own defenses. Each plant can lose up to 30 percent of its leaves and survive. In response to the chemical signal, the damage was spread out over stands of goldenrod. This seems like a win-win: the plants aren’t mortally wounded, and the insects get what they need.

    So as I walk around the garden noticing damaged leaves on just about every plant, I remind myself that there are enough leaves to go around. 

 

Leaf miner at work on a columbine

And I’m definitely one of those gardeners who doesn’t notice the chewed parts when I shift my attention to taking in the whole plant. Just as well.

 

Columbines: Johnny-on-the-spot

 Some of the toughest plants in my garden are columbines (Aquilegia spp.). While other plants in a newish bed off the deck have started to turn brown and lose leaves during the current drought, the columbines are holding on.

 

Columbines bloom here in May and June

    I appreciate the way these easy growers pop up around the garden wherever there’s open soil. This trait of filling in where they’re needed has been especially convenient in areas where I’m waiting for slower growers to get established. 

     In the deck bed, I planted a combination of low growers and medium-height mound-formers, aiming for a tapestry of pollinator-attracting plants that would cover the soil densely. That hasn’t happened yet. The bearberry (Arctostaphylos uva-ursi) I hope will eventually form a mat of small shiny leaves is just starting to spread. New native perennials need time to grow wide. While they’re gathering strength, the columbines are helping out. 

 

Columbines in the deck bed in June

     I have lots of young columbines to choose from. In the vegetable garden alone, each spring reveals a selection of new seedlings. It’s a happy spot for them. The rich soil is renewed annually with compost, and there’s little competition in early spring before food plants have filled the space. 

 

Columbine volunteer in the vegetable garden

I can dig up columbines wherever they aren’t needed and move them to where they are. Three have settled in comfortably around those young bearberries.

    I started out with a broad selection of columbines, some blue-flowered or blue and white, some rose pink, some deep plum purple. The combinations of traits showing up now reflect interbreeding between these varieties. Columbines aren’t shy about spreading their genes around.

A later generation

     Since the 1960s, there’s been an effort to categorize plant strategies, the approaches that plant species employ to defend themselves, survive, compete, and reproduce. Columbines have chosen the role of ruderal plants—pioneers in disturbed areas. They sprout where a natural event or human activity creates an opening. They produce lots of seed that drops wherever there’s a favorable place to grow. They grow fast, covering ground quickly. When they’re crowded out by expanding clumps of stronger growers in one area, they move to another. They live short lives, but their offspring take their places so seamlessly that I can’t tell when an older plant dies and a younger takes over.

New columbines bloom each spring

     Claudia West and Thomas Rainer, in their book Planting in a Post-Wild World, recommend leveraging these plant strategies in designing for visually impactful native plant communities. They divide plants into four categories. In the first group are the taller structural or framework plants, from trees to shrubs to large perennials and ornamental grasses. Second are the seasonal theme plants, such as my rhododendrons (Rhodendron catawbiense), black-eyed Susans (Rudbeckia hirta), and asters (Symphyotrichum spp).

 

Native Catawba rhododendron

 Third are groundcover plants such as wild geranium (Geranium spp.), foam flower (Tiarella cordifolia), and barren strawberry (Waldsteinia fragaroides) that control erosion and provide nectar for visiting insects.

 

Foam flower

 
Last are the filler plants, and that’s where the columbines fit in. They fill the gaps. That’s what I love about them.