Sustainable-enough potting mix

To test the usefulness of my homemade potting mix and compare it to commercial products, I’ve been working this winter on propagating African violets. I made the potting mix to avoid using peat, which I learned is not a renewable resource. The mix is half compost from my yard and half coir, or coconut fiber.

    Like so many of my gardening methods, it’s “sustainable-enough” rather than ideal. That’s because the coir comes from Hawaii, accruing significant carbon cost on its 6,000-mile journey to Massachusetts. On the plus side, coir is a byproduct that I can put to good use, and compared to depleting peat bogs, which are major carbon sinks, I think non-local coir is the better alternative.

    I’ve had luck with African violets as houseplants probably because they tolerate neglect. My collection has been living for years on pebble trays next to an east-facing window. Their winter blooms are a morale booster. I’ll betray my amateurism by admitting that I haven’t kept track of the names of the varieties I’m growing. My favorite has blue flowers and purplish foliage. 

The pink ones are nice too.

    I wanted to try multiplying my collection by rooting single leaves. I cut off a few with stems about two inches long and stuck them into moistened potting mix in November. I enclosed them in plastic bags for a humid environment and put them under a grow light in the kitchen. Nothing happened for many months.

    Meanwhile, I discovered an excellent youtube video demonstrating how to propagate African violets from leaves, made by an anonymous benefactor who obviously knows what she’s doing. After watching her demonstration, I was able to start a new batch with several improvements in my technique.

    First, since the new sprouts grow from the cut end of the stem, I cut the stems shorter. I used smaller pots and didn’t tamp down the potting mix. I learned to cut the stems at a slant for more surface area and to cut the leaves in half to encourage them to put their energy into reproduction rather than photosynthesis and leaf enlargement. 

    This week I noticed some little leaves growing up at the base of the old ones in both batches. 

I took the pots out of their plastic bags and gingerly dug out the mother leaves. Voila! There were little plantlets growing from the cut ends. The new leaves were no more than a quarter inch long, some much smaller, but they had their own roots. 

 

    I pulled the babies away from the mother plant, doing my best not to break them. I planted the best ones in a recycled six-pack from last year’s garden center annuals, 

encased them in another plastic bag, and replaced them under the grow light. With luck, I’ll have reasonable-sized plants to enjoy or share next winter.

    The non-peat potting mix did its job just as well as the peat-based mix I used to use. Score one for sustainability.

Almost spring

Is it late winter or early spring? The calendar date is still far from the vernal equinox, but on the glass-half-full side, the garden is already starting to wake up. Snowdrops have been blooming since early February. 

 
Our first flowering tree is in bloom, a witch hazel, Hamamelis ‘Arnold Promise.’ 

I’m declaring the start of the gardening season—whoopee!

    It’s time—or past time—to order seeds to plant this spring. I’m feeling a new appreciation for seeds. In doing the research for my book, I learned to my surprise that producing plants for garden centers is far from a local enterprise. I had imagined just one step between a grower and the garden center where I shop. The reality turned out to be much more complicated. I had to come to terms with the fact that plants I bought came with a significant carbon cost.

    Perennials come from multiple starting points, depending on the plant. Jan Lesnikoski, a grower at Sunny Border in Connecticut, explained to me that wholesale nurseries buy seeds and plants from around the world. Sunny Border uses tissue culture products imported from South Africa, Holland, Turkey, and Poland (tissue culture converts tiny pieces of plant tissue into large numbers of genetically identical plantlets). Large plantations in Costa Rica and Ecuador with space to maintain supplies of stock plants send unrooted cuttings for Sunny Border to root and grow to saleable size.

     Garden centers like the one I favor, Russell’s in Wayland, Massachusetts, do grow annuals and vegetables on site, either from seeds or from plugs (small young seedlings) they buy from regional wholesale brokers. 

    This new knowledge about global sourcing makes starting plants from seeds seem more desirable. Although seeds may come from all over the world, they’re small and packaged by nature for easy travel, so shipping them incurs less environmental cost.

    This year I’m planning to buy my usual vegetable and annual flower seeds: arugula, lettuce, peas, beans, cucumbers, nasturtium, sunflowers and zinnias. Most I’ll plant directly in the garden; a few I’ll start indoors under lights. 

    Renewing my membership in the Massachusetts Horticultural Society yielded a gift certificate from White Flower Farm. Despite wanting to be more sparing about buying perennials, I think I’ll use the gift to buy some that are popular with beneficial insects I’d like to attract.

    I have my eye on a selection of coastal plain Joe Pye weed that's native to the eastern US. 

Eupatorium dubium 'Baby Joe'

It stays 3 to 4 feet tall, smaller than Eupatorium maculatum, the species I’m used to seeing. I also want a butterfly weed

Butterfly weed, Asclepias tuberosa

to complement the swamp milkweed, Asclepias incarnata, that I grew last year.

    My ambition is to learn more about growing native perennials and shrubs from seed. That way I can expand my supply of plants without incurring the carbon cost of shipping them from around the country or around the world.

Where water is scarce

We came home Saturday night from a week away from the Massachusetts winter, visiting Austin, Texas and Las Vegas, Nevada (Sunday morning the thermometer read -5 degrees, a reminder of why we left). Both cities have climates very different from Massachusetts’. It was nice to get away from the snow, and it was also a good lesson in what kind of gardening is feasible in areas with less rainfall.

    Austin’s climate is classified as humid subtropical, with 228 average sunny days per year and 33 inches of annual precipitation, less than the national average and a lot less than my area’s 45 inches. 

Water-sipping live oaks line a street in the SoCo section of Austin

During our four-day February visit, the weather was lovely, sunny and in the sixties. The plants that caught my eye as most striking and emblematic were agaves.

A giant agave, right, next to a prickly pear

 Huge ones grew in many front yards, where admirable residents were planting appropriate, water-efficient natives.

Tanks store rain for watering Zilker Botanical Garden

     
 I visited the Zilker Botanical Garden, where an impressive water harvesting system collects rainfall to irrigate the garden.

 
     Las Vegas, of course, has a hot desert climate with 4 inches of rain per year, and it’s almost always sunny. During our visit we enjoyed daytime temperatures in the sixties and seventies. 

     At the Botanical Garden at the Springs Preserve, I saw what kind of plantings would be climate-appropriate, including a collection of Mojave Desert cacti and succulent plants. 

The nearby Nevada State Museum featured exhibits on how the construction of the Hoover Dam supplied the city’s water needs. Despite strenuous conservation efforts far in advance of what we see in the East, Las Vegas couldn’t exist without water from Lake Mead.

    This visit to the arid zone reminded me to appreciate Massachusetts’ relatively plentiful water supply. We can learn a lot about water harvesting and conservation from places like Austin and Las Vegas that have been forced to get good at it. Nonetheless, we start with a lot more water to work with. When May comes, I’ll be glad of that.

Full circle in a lifetime

My generation has lived through a sea change in how we conceptualize soil and fertilizer. We’ve come a long way from uncritical acceptance of chemical products after World War II.

       Today every school child hears about how the soil cycle works.  In undisturbed fields and forests, nature returns nutrients and organic material to the soil through a continuing process. Plants use sunlight, water and soil components to grow. Dead leaves and branches fall to the ground, decompose, and feed soil organisms that in turn provide nutrients for the next generation of plants. 

Leaves decompose into soil

    To understand how soil can be improved, New England school children learn that the Wampanoags added a fish to the hole when planting their hills of squash, beans and corn. As the fish decomposed, it fertilized the plants.

    So why didn’t I hear about building soil when I was growing up? It was because of something that happened between New England’s bucolic past and my birth in the Baby Boom.

    In the early twentieth century, German chemists invented an industrial process for fixing nitrogen from air, ushering in a radical change in the way farmers and gardeners thought about soil fertility. For a while it seemed as if synthetic fertilizer would replace traditional soil amendments such as manure and composted plant material. 
 
    During the twentieth century, the combination of manufactured high-nitrogen fertilizer, new high-yield grain varieties, and potent pesticides like DDT enabled the developed world to increase food production. Starting in the 1960s, a Green Revolution followed for areas of the Third World where famine was a chronic killer.

      I didn’t know it when I first encountered chemical fertilizer at age four, but I was living in a unique era in gardening history. Because I grew up with them, I thought those bags of 5-10-10 had always been around. Before the slogan became a joke for druggies, I remember a DuPont poster in my tenth grade chemistry classroom touting “Better Things for Better Living . . . Through Chemistry.” 
 
    But there was a dark side to farming with the new chemicals. Starting in 1962, Rachel Carson’s Silent Spring awakened Americans to the dangers of indiscriminate use of pesticides, exposing how DDT spread its lethal effects up the food chain. Meanwhile, soil scientists were noticing that intensive crop production with chemical fertilizer did not maintain soil fertility, and soil and water were being poisoned by over-fertilization and overuse of irrigation.

    As Americans questioned conventional ideas in the sixties and seventies, J. I. Rodale’s magazine Organic Gardening started to gain traction. Rodale had founded his magazine in 1942, with Albert Howard, a British pioneer of the organic movement, as associate editor. Organic techniques hadn’t completely died out with the advent of chemical fertilizer, of course, but there had been enough mass forgetting that the ideas Rodale proselytized were initially regarded as somewhere between cranky and dangerous. As the counterculture grew, his message found receptive readers.

    Seventy-four years after OG’s birth, there’s organic food available in every supermarket, and gardeners like me aim to improve soil without chemical fertilizer. Living through such a radical change in point of view makes me wonder what shibboleths the next generation will find to be dangerous and unjustified.

An attractive menace

On July 14, I wrote about doubting I could keep my potentially invasive silk tree (Albizia julibrissin, also known in the US as mimosa) from spreading. Now that looks even more unlikely.

    With last weekend’s snowfall mostly melted, I notice many silk tree seed pods lying on the grass. Some are empty, and some still contain their brown seeds.

    Silk tree is a native of Asia that was imported to North America in 1745. It's a pretty tree with delicate, feathery foliage that makes pink puffs of flowers in July in my yard. 

This is a photo from Texas. Mine don't flower this densely

Silk tree spreads especially in disturbed ground and is now invasive in the southeast US. It has a number of characteristics that enable invasiveness: it produces a lot of seeds, it’s a legume, so it can extract nitrogen from low-nutrient soil, and if reproducing by seeds fails, it can also spread vegetatively from root fragments. 

     Its seeds require scarification (breaking through the seed coat mechanically, chemically or with heat or cold) to sprout and without this can stay dormant for many years before germinating, which allows them to seize growth opportunities when they arise. The seeds are efficiently dispersed, initially by gravity, secondarily by wind, water and animals. 

    That may explain why I’m finding the pods farther and farther from the tree, some at least 50 yards away on the other side of the house. More ominously, I see some have left our property and made it to neighbors’ lawns. I’ve found clusters near tree trunks, so it may be that squirrels or birds are carrying the pods away to eat the seeds and are dropping pods on the ground under the branches. 

    In this weekend’s thaw I’m picking up as many of the pods as I can and throwing them in the trash—I won’t compost them, because that would probably just distribute viable seeds wherever I spread compost. 

     I’ll be sorry to lose this pretty tree, but next spring I think I’ll have to cut it down.

Beautiful but damned

 

Littering, dog poop, and the climate change accord

With snow making gardening a memory and a hope, I want to write this week about a larger environmental topic. I’ll start at ground level.
     One of the great questions that has haunted me all my life is why people litter. What are you thinking when you go to a conservation area for a walk in the woods and drop your soda can or lottery ticket beside the path?  

Now it strikes me that littering has something to tell us about addressing climate change.
     I’m a dog owner, so I find behavior around dog poop particularly puzzling and frustrating. A significant minority of owners bags the dog waste and then leaves bags along the path or sidewalk. They may intend to come back and retrieve the bags at the end of the walk, but I can testify that many of those bags get left behind. 

     Psychologist Robert Cialdini and colleagues actually researched determinants of littering in 1990. In a 2014 Atlantic interview, Cialdini asked a better question than mine: why don’t people litter? “The crucial question is why don’t they litter, since the easy thing is to litter . . . Their attitudes toward the environment make a difference, but what they perceive as the norm is key.”
      As we ask ourselves how to translate the climate change accord’s commitments into action, we could take a lesson from Cialdini’s research. By presenting cues suggesting that littering is socially unacceptable, his group was able to make people in a library parking lot less likely to drop a handbill left on their windshields to the ground.
      Maybe those dog owners I criticize are getting cues from their dog-walking circle that dropping poop bags on the ground is the norm. In my friend group, driving a hybrid car allows me to pat myself on the back for being part of the solution. I was happy with that until someone pointed out what a tiny step it was on the road to sustainability.
      An adjustment of norms could help rein in the ultimate form of litter, carbon emissions. The conference delegates in Paris seem to have had something like that in mind when they set up the transparency aspect of the agreement, requiring governments to report back on emissions reductions. A California utility company has already demonstrated success nudging homeowners to reduce electricity use by comparing their use to neighbors’. No one wants to be the loser in a competition.
      We’re going to need systemic changes that make it the norm—easier and more consistent with our self-image--to conserve energy and switch to renewable sources than to stick to our old ways. Asking nations, communities, and individuals to do what’s harder and more expensive because it’s right can only get us so far. Systems have to change so that people can. We’re ready to do our part, but without that bag conveniently at hand and the trash barrel at the park gate, we’re likely to leave the dog poop on the ground—and drive off in that Prius. 

 

For the birds

     I heard a wonderful talk last week by Claudia Thompson, founder and president of Grow Native Massachusetts. Claudia spoke at a meeting of the Temple Shalom Garden Club in Newton.

    Claudia’s topic was the importance of growing native plants in home gardens. She illustrated how she created a lovely native plant garden in her yard in Cambridge.

    By planting native trees, shrubs and perennials, Claudia created habitat for many native animals, from soil organisms to insects to an amazing number of bird species. Photos from her yard captured birds I never expected would frequent a city garden.

    After hearing Claudia’s talk, I’m fired with enthusiasm to provide habitat for native birds in my own yard. I walked around the garden considering what I’d done for the birds and what else I could be doing.

    Claudia listed basic bird needs: food, in the form of insects, seeds and fruits, water, shelter, and cover for nesting and foraging (more information is available on the group’s website, www.grownativemass.org). She provides all of these necessities in a small garden, for example she attracts flocks of beautiful cedar waxwings who feast on the spring fruit of a grove of amelanchier, a small tree commonly known as serviceberry, juneberry, shadblow or shadbush. I’ve seen cedar waxwings farther north in the Adirondacks, never in my garden.    

      Looking at my own yard through the lens of Claudia’s talk, I recognized that I do have trees and shrubs of varying heights, including evergreens, that allow birds to flit safely from perch to perch. Two birdbaths are located near cover so that birds can feel safe. 

Birdbath beneath a thistle seed feeder

I’ve got quite a few native plants that provide food for birds, from towering conifers to low-growing native perennials. I even have two amelanchiers that produce the garden’s first tree fruit of the year in June.
  

     A knowledgeable birder, Claudia recognizes the call of the cedar waxwings when they arrive to check out her trees. I can’t identify them by ear, and I don’t spend enough time in that corner of the garden to spot them if they did come. The amelanchier berries disappear quickly. It’s possible that flocks of hungry waxwings are swooping in undetected. That’s not a completely satisfying thought. I wish I’d planted the trees within view of the house, as Claudia did.

      An area where I need improvement is my leaf litter management. Claudia reported that fall leaves lying on the ground, which I’ve been chopping in my leaf shredder for mulch, harbor insects and snails that play important roles in the garden ecosystem, including providing food for birds. She recommended letting the leaves alone to decompose in place.

      Whole leaves blow around, and in front of the house that’s a problem for my neighbors, who work to keep their lawns leaf-free in winter. To meet the neighborhood standard, I’ll need to keep raking and chopping leaves that drop in the front yard.

Leaves blow around if left on ground cover beds in front of the house

In back, though, I’m convinced I should try Claudia’s system, raking leaves off the lawn but letting them lie unchopped on the beds, even near the house.

Coral bells (Heuchera 'Montrose Ruby') under fallen leaves this winter

Then I want to find out more about native plant communities—and learn some bird calls.