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Sunday, December 31, 2017

Less is more

Happy New Year! Amy Andrychowicz advises in the Savvy Gardening Newsletter that gardeners write “garden reflections” at the end of each year, documenting what went well and badly in this year’s garden and what can be improved next year. Here are some of mine:

    What went well? A lot that wasn’t in my control. We got plenty of rain! That kept the garden lush and flourishing. 

Rain made everything grow

    Also good was that the destructive nonnative winter moth dwindled my area. Tachinid flies (Cyzenis albicans) released by UMass professor Joe Elkinton are killing winter moth larvae. I counted three or four moths at the front porch lights this fall, nothing like the clouds of them we’ve seen in previous years. With so few parent moths, I predict few caterpillars will show up next spring to defoliate and weaken our trees.

There should be less winter moth damage next year
    Thanks to a much-abbreviated work schedule, I was in the garden most days all season. That gave me a chance to start addressing a list of dozens of tasks and projects I’d put off over the past decade. 

    This year I got to tear out a big patch of lawn and replace it with new perennials, mostly native species. It doesn’t look like much yet, with little plants surrounded by wide stretches of mulch. In three years when it’s filled in, I’m expecting a lush habitat for birds and native insects, as well as a pretty sight from the back of the house and the deck.

With luck, these little plants will grow wide and tall

    Restricting my container choices to neonicotinoid-free plants also turned out well, better than I’d expected. Maybe a smaller palette of choices prevented over-complicated compositions.

Simpler container combinations did better

    What didn’t go so well? Despite the plentiful rain, my vegetable garden didn’t produce a lot. Two problems stick out. First, I planted intensively with not much space between plants and rows because I’ve got so little sunny ground. That meant overcrowded plants didn’t get all the sun they needed. I didn’t leave enough space for paths, so while trying to spring lightly in and out of the beds, I stepped too close and packed down soil where roots were trying to grow.

Tight quarters in the vegetable garden

    This was the year I noticed my trees were crowded too, bent out of shape by competing to reach the light. That’s because of mistakes I made twenty years ago planting them too close together, like those vegetables. Having done that, I could have pruned more aggressively than I did. Back when the trees were young, I was afraid I’d kill them if I cut back their young branches to direct their growth. Now I know better.

Cramped trees

    The takeaway? Less is more. Make the hard choices and plant what I really have room for. Plan for the full-grown size, whether of 12-inch-tall bean plants or trees that will reach 60 feet. Failing that, don’t be too sentimental to thin out the extras when it’s time. Will I live by this insight and refrain from overcrowding the new perennial bed? Time will tell.

Sunday, December 24, 2017

While the weather outside is frightful

Outdoors it’s winter, but plants still grow and even flower indoors, despite short days. During winter, I try to nurture houseplants in a sustainable way by limiting turnover, minimizing use of materials with high carbon cost, and carrying over outdoor plants that can make it through the winter next to a window or under lights.

Geraniums and succulents making it through the winter under a grow light

    Some of my houseplants may be older than my children. I can’t resist treating them like pets and keeping them even when they aren’t beautiful. This winter I’ve added some pretty young variegated ivy and a fern to the collection. 

Variegated ivy can thrive indoors and out

I’ve had good luck transplanting low-light selections like these in spring to a large box planter in a shady area. This way I can enjoy their foliage through both the winter and the summer. The fern will succumb to next fall's frost, but the ivy may tough it out and become a perennial.

    Winter blooms of African violets, orchids, paperwhite narcissi, and amaryllis will add some welcome color to this mostly green scene.

African violets blooming in February

    I also rooted cuttings from some of the neonicotinoid-free geraniums, coleus, begonias, and rosemary that I bought last spring to plant in summer containers.

A confused geranium blooming this week

It was difficult to find plants that hadn’t been sprayed with the pollinator-toxic insecticides. I’ll be able to use the old plants’ descendants next year and avoid the search for untreated plants. The youngsters aren’t going to get me into House Beautiful, but I think they look cheery under a grow light in the kitchen/family room. They’re located where I can’t miss seeing them, so I notice when they need care.

    By recycling plants from last summer, I avoid the carbon cost of new plants. This can be considerable, because they often travel to local garden centers from remote parts of the country and the globe. I also reuse the plastic pots and six-packs that my plant purchases came in. 

Ready for starting seeds in early spring

Washing the soil out of these and storing them in the basement is a winter activity. Like the indoor bulbs, cuttings from summer plants are grown in homemade peat-free potting mix. By using this growing medium instead of commercial potting mix, I spare the peat bogs, which sequester much of the world’s soil carbon.

    I’ve long had a fantasy of enclosing a small porch at the side of the house in glass to use as a greenhouse or conservatory. 

The conservatory at Tower Hill Botanic Garden

In addition to the cost, a concern that holds me back is how I’d cope with infestations and plant diseases indoors. The greenhouse manager at the Arnold Arboretum once told me that they emptied the greenhouse once a year to clean it thoroughly and spray it with diluted chlorine bleach. The prospect of donning a hazmat suit and mask to spray an indoor space with chlorine or other toxic pesticides cooled my enthusiasm for a greenhouse attached to our living space.

    Unlike the Arboretum staff, I’m not growing irreplaceable specimens. If indoor plants get sick or attract insects, they’ll find themselves filling another sustainable role—as compost.

Happy holidays, inside or out!

Sunday, December 17, 2017

Better red than dead

In my yard, this year’s fall foliage was pretty much a dud. In particular we didn’t get the bright reds we usually see on our Japanese maples, 

Most years a maple in the front yard turns bright red

neither on a purple threadleaf variety in the backyard (Acer palmatum var. dissectum) nor on a broader-leafed version in the front. Most years they see the foliage season out with glowing scarlet leaves. This year the leaves just turned brown, shriveled, and hung on. Last weekend’s snow hung dishearteningly on the brown leaves.

This year leaves turned brown and hung on

    I feel cheated. Why did this happen? I thought this had been a favorable growing season. Some Internet research convinced me that it’s hard to know exactly why fall foliage is dramatic one year and drab another, because several factors interact to produce the autumn display. But it’s clear that events conspired this fall to prevent formation of the red pigments, anthocyanins, that give red maples and Japanese maples their gorgeous red fall color.

Late October 2015, same tree as the one above

    We were relieved this spring when rainfall stayed ahead of the annual average. By early summer, New England precipitation was well ahead of expectations, making up for last year’s drought. As of December 15, we were still ahead, with 42.30 inches of precipitation for the year, compared to the normal year-to-date total of 41.79 inches. 

    But the fall months demonstrated the swings between extremes we can expect with climate change. Around Labor Day it was unusually cold, then we had a heat wave later in September with temperatures up to 90. Heat and humidity kept the leaves on the trees. Although the tail end of Hurricane Philippe swept through our region late in October, bringing flooding and high winds, this fall season was short on rainfall. That already meant that foliage color was likely to be dull.

This fall's conditions weren't favorable for bright leaf color

    What signals trees to prepare to drop their leaves is a combination of longer, cooler nights and less intense sunlight. They get ready for winter by stopping production of chlorophyll, the pigment that enables photosynthesis and makes leaves look green. With only their yellow xanthophyll and orange carotenoid pigments remaining, leaves look yellow.

Witch hazel leaves turn yellow without chlorphyll

    For red and purple color, leaves need sunny days and cool but not freezing nights. These conditions trigger production of anthocyanins from sugars left behind in the foliage when trees cut off transport of materials in and out of the soon-to-be-jettisoned leaves. 

Red color made from stored sugars

My conclusion is that this November’s cold snaps with temperatures in the twenties cut off this process before our Japanese maples could turn red.

    Every gardening year is different, of course, and we can’t attribute all weather variations to global warming. There does seem to be a trend at work here, though. Researchers in phenology, the study of changes that occur seasonally, say that warmer temperatures lasting later into the fall are causing delayed leaf senescence and therefore later appearance of bright fall foliage. 

     We can only hope that next year Japanese maples will have time to turn red before winter cold intervenes. 

It's nice when each plant shows its fall leaf color

Sunday, December 10, 2017

Life support

With the first snow this week, my spirits plummeted. Winter is really here, and I wish we could fast-forward to April 1st.  

Not this again!

Since we can’t, it seemed like a good time to plant some indoor flower bulbs to get me through the cold, dark months.

    My bulb choices this winter are paperwhite narcissi (Narcissus papyraceus) and amaryllis (Hippeastrum species).

Paperwhites have a lovely scent-photo by Ceasol

You really can’t fail with these bulbs, which contain everything they need for flowering when you buy them. 

You can't beat amaryllis for big beautiful flowers in the dead of winter-photo by pizzo disevo

A bulb is a storage mechanism that allows the plant to get through dry periods. It’s made up of embryonic leaf, stem and flower tissues surrounded by fleshy scales that contain food stored up during the plant’s growing period. An onion is a bulb too; the rings of flesh are its storage scales.

    Once you plant them and they start taking up water, bulbs send out roots from their base plates, and stems start to extend upward. They’re going to do it whether you help them or not. In fact, unplanted bulbs start putting up flower stems if I leave them in the basement for too long before planting them. 

    I prefer to pot the paperwhite bulbs in homemade potting mix. I make the mix by combining coir (coconut husk fibers) with compost from my compost piles to avoid using peat-based medium, which is not a sustainable product. I find that paperwhites grown in the potting mix stay more upright than bulbs grown in bowls of pebbles.

Once covered with potting mix, the bulbs can be watered and set in a cool, dark basement spot for a week or so until they start sending up new growth

    Amaryllis bulbs are gigantic. The one I planted weighed more than 15 ounces, with a diameter of 5 inches. 

Hubba hubba!

I usually get four flowers on each stalk. A second stalk often emerges a few days after the first. I nestled this bulb in a pot just wider and taller than itself. Only a little potting mix was needed to fill in the remaining space. 

I set the amaryllis pot next to a radiator to help it start growing. I'll move it to a cooler windowsill once the flower stalk starts extending

    Anyone who has a window with a bit of sun can get flowers from these bulbs. The harder challenge is to get them to flower again the following year. The paperwhites originate in the Mediterranean. They need a warm climate and won’t survive in New England gardens. For us, they’re annuals.

    It’s tempting to try to get amaryllis to rebloom. In their natural habitat in South Africa or South America, after flowering the bulbs would soak up sun and soil nutrients for a couple of months before dropping back into dormancy, waiting for the signal to flower again. It takes a lot of sun to pack in the same amount of stored energy in our area. Here are some instructions from the National Arboretum.

    My experience has been that with lots of trouble, I can get amaryllis leaves to grow the next year and, rarely, one small flower cluster. It’s not worth it. I pay the $15 for the big bulbs and throw them on the compost pile when they’re finished blooming. All good things have to end—and winter does too.

Sunday, December 3, 2017

Shredding less and enjoying it more

I’m enjoying not shredding leaves this fall because of a new approach to mulch. This year I’m going to let whole leaves lie on the garden beds. It’s all for the insects.

Whole leaves as mulch

    I’ve been evolving a strategy for mulching with fall leaves for more than 30 years. Back when I started my garden, I tried piling whole leaves on garden beds, but it soon became obvious that they wouldn’t stay put. Instead, they blew around and landed on my neighbor’s lawn. Since he raked meticulously almost every day, I could see this was going to be a problem. 

    That’s why I started using a leaf shredder—essentially a string trimmer in a drum—to chop up fall leaves into mulch. 

Leaf shredder

The shreds were pretty, they definitely improved the soil as they decomposed, and they didn’t blow around the way whole leaves did. I could use them for mulch in the front yard without making myself unpopular in the neighborhood. 

Shredded leaves make pretty mulch

    For years I shredded leaves every fall to mulch the beds close to the house. By default, the beds farther from the house ended up covered with unshredded leaves.

    Last year I heard something that persuaded me to change my approach. Claudia Thompson of Grow Native Massachusetts spoke at my garden club and explained that native insects benefit from leaf litter. By shredding leaves, I was chopping up insect eggs laid on the leaves and eliminating habitat for adult insects that need to overwinter under fallen leaves.

    This year instead of shredding the leaves, I’m just raking them from my lawn and my neighbors’, piling them on a tarp, and dragging them over to dump on the garden beds. 

Leaves on their way to backyard beds

Because I eliminated a whole area of lawn this year and replaced it with a bed of native perennials, I don’t have to worry about errant leaves damaging lawn grass. If leaves from the new bed blow around, they’ll just land on paths of woodchip mulch or bluestone.

New bed surrounded by paths, no lawn grass

    While I pat myself on the back for upgrading my sustainable practices, I’m also doing a lot less work. Just moving the fallen leaves to the beds is much easier than feeding them into the shredder drum. It was never fun replacing worn filaments, breathing leaf dust, or having my face stung by flying fragments (goggles and heavy gloves were a must). I still plan to shred a few leaves for the front yard.

    We’ll see how this new approach works next spring. Conventional wisdom teaches that whole leaves mat down and have to be removed to let perennials reach the light in spring. Claudia said she doesn’t have this problem in her garden of native shade-lovers. 

Will bloodroot flowers be hidden by matted leaves?

     Worst case, I’ll have to move some leaves in spring when it’s warm enough for insects to emerge from winter lodgings. Meanwhile, I can give the shredder a miss and tell myself I’m conducting an important experiment!

Sunday, November 26, 2017

Holiday choices

With Thanksgiving passed, we’ve entered the period for buying Christmas trees. Already an outdoor stand near us has stacks of trees ready to sell, and I’m seeing station wagons cruising by with trees strapped to their roofs.

Ready to go

    In my present state of constant background worry about climate change, my reflex is to think that cutting down trees is a bad thing. But what’s the total environmental impact of Christmas trees? Predictably, tree farmers say that real trees are more environmentally friendly, while makers of artificial trees argue that man-made trees can be just as sustainable.

    Proponents of natural trees point out that used Christmas trees can be recycled to make mulch. Like many cities, ours picks up trees at curbside after the holiday for this purpose. Tree farms provide wildlife habitat, if pesticide spraying doesn’t poison animals trying to move in. Whole trees can be laid down to prevent erosion, and if all else fails, used trees can be fed to goats!

Christmas trees stabilize a Connecticut beach

    The trees themselves are carbon neutral over their lifetime. When harvested, they give up the same amount of carbon that they took in. There’s carbon cost for powering machines used in farming—did you know that Christmas trees have to be sheared annually to create dense, uniform foliage? 

Christmas tree farm

Shipping harvested trees to the point of sale also uses fossil fuel, so it’s good to buy local. In all, production of a live tree that makes its way to your home generates an estimated 6.8 pounds of greenhouse gases per year of the tree’s life.

    By comparison, cars and trucks account for an average of 24 pounds of greenhouse gases per gallon of gasoline.

Christmas trees are paltry polluters compared to cars

    A 2008 study from a group of sustainable development consultants in Quebec found that artificial trees have lower environmental impact only if they’re used for at least 20 years. 

Buying an artificial tree could be the start of a long-term relationship

An alarming wrinkle: many of the artificial trees currently in use are made of recycled plastic, usually polyvinyl chloride, that has been stabilized with metal. What metal did Chinese makers add? You guessed it: lead. The plastic degrades as it ages, and at nine years, it starts to give off lead. Use of lead in plastic Christmas trees has recently been outlawed in China.

    I’m not in the market for a Christmas tree, but if I were, I’d be tempted to buy a living tree in a pot and grow it in my yard once it had played its part in the holiday celebration. 

A petite balsam fir (Abies balsamea)

Clemson Cooperative Extension in South Carolina describes the pitfalls of this approach. Trees that spend more than 10 days in the hot, dry indoor environment aren’t likely to survive being planted outdoors. Planting sooner is better, but that’s assuming that the ground isn’t frozen after Christmas. As an alternative, Clemson suggests planting a tree in your yard and decorating it there.

    As always with personal environmental decisions, assigning weights to these factors is complicated. My conclusion: enjoy your Christmas tree, park the car, and try to walk more.

Sunday, November 19, 2017

Mulch falling from the trees

My new perennial bed near the back of the house is covered with needles from a big white pine (Pinus strobus) nearby. 

Pine needles on the new bed in October

When the area was lawn, I didn’t notice how many needles fell from the tree, perhaps because our focus was on raking them off the grass.

    Now I realize that those pine needles are providing natural mulch without my intervention. Is that a good thing? A couple of persistent urban legends warn against pine needle mulch.

    In the South, you can buy compressed bales of pine needles, commonly called pine straw, in various shapes and sizes at the garden center. 

Bales of pine straw at Space Coast Landscape Supply in Florida

Proponents point out that this mulch is pretty, it’s slow to decompose because of the needles’ waxy coating, it doesn’t blow around or pack down to create a water barrier, and it’s less dense than bark mulch. A 40-pound bale of pine straw covers as much ground as 30 cubic feet of other much heavier mulches. By contrast, big bags of bark mulch that I purchased recently contain 3 cubic feet each. I can barely lift them, and a bag covers a dishearteningly small area.

Bark mulch, heavy as all get out

    Tossing pine needles around has got to be easier than schlepping those bags of bark mulch. Having the tree and the wind spread pine needles is even less work. (My recent mulch favorite, arborist wood chips, also has the advantage of being less dense than bark).

Arborist wood chips make great mulch too

    It’s often suggested that pine needle mulch will acidify soil. The argument is that since the needles have a lower pH than average soil, adding them to soil must make it more acidic. Many gardeners hesitate to mulch with oak leaves for the same reason. But science doesn’t substantiate this.

    Soil has tremendous buffering capacity. As Robert Pavlis points out in this blog post, rain becomes acidic as it falls, picking up carbon dioxide from the air and converting it to carbonic acid. This is true even without the pollution that causes acid rain. If rain hasn’t changed soil pH over millennia, you’re not going to do it with a few pine needles or oak leaves.

Pine needles can't overpower soil's buffering capacity

    Second, pine needles contain a group of organic compounds called terpenes that people worry may suppress growth in the garden. Terpenes act as insecticides, preventing insects from eating the needles. They may also help suppress growth of other plants under the tree. But once the needles fall from the tree and hit the ground, the volatile terpenes quickly float into air or water—that’s why the needles stop giving off that pleasing pine scent. Plants can and do grow under our white pine.

Shade lovers growing at the base of the white pine

    Recent research suggests terpenes help trigger rainfall by combining with free radicals and oxygen in the atmosphere, forming aerosols of polarized molecules that collect water and grow into clouds. Trees aren’t as passive as we used to think!

Conifers don't just wait for rain

    I’ll soon be able to assess whether pine needles are improving soil, suppressing weeds, and helping to retain moisture in my new bed. I’m optimistic.

Sunday, November 12, 2017

Picky eaters

Something I learned from entomologist Doug Tallamy’s book Bringing Nature Home is that most insects specialize. Ninety percent of herbivorous insects depend for food and shelter on a few plants they coevolved with. This insight is directing me toward different plant choices.

    I used to think that leaf-eating insects ate any leaves they could get. Tallamy explains that, on the contrary, over the millennia insects have survived by tailoring their behavior and physiology to be able to sense and locate a few plant species. 

Not just any leaf will do for food

They’ve synchronized their life cycles with the plants’. They’ve developed ways to get around the plants’ defenses. As they’ve invested in these food sources, they’ve become less able to live off others. That’s why most need plants from their local region and can’t eat plants from other parts of the world.

North American native insects can't eat plants that originated in Asia

    This year I’ve expanded my collection of milkweeds for monarch butterflies, the poster children of insect specialization. Monarch caterpillars have evolved to be able to eat milkweed leaves, which contain defensive chemicals called cardenolides that make the caterpillars and adult butterflies poisonous for other animals. 

A monarch on showy milkweed (Asclepias speciosa)

When eggs laid on milkweeds hatch, the caterpillars have the food they need to grow and metamorphose into another generation of beautiful adult monarchs.

    Monarchs are now under great stress. They need to fly from their winter home in Mexico to summer habitat in the US. 

Wintering in Mexico-photo Steve Bridger

Here they find less and less milkweed because of herbicides such as Roundup (glyphosate) that are widely used in industrial agriculture. Organic farmers make a point of leaving weed strips around their fields for the sake of pollinators, including butterflies. Until that becomes universal practice, home gardeners are encouraged to grow some milkweed for the monarchs.

    I started with swamp milkweed (Asclepias incarnata), which turned out to be quite easy to grow. Swamp milkweed’s dusty pink flowers are clearly an insect magnet. Not only the monarchs benefit.

Swamp milkweed attracts lots of pollinators

    This year I tried butterfly weed (Asclepias tuberosa) again. I’d planted this species twice before, only to see it dwindle without flowering. With a sunnier spot and plenty of rain this spring and summer, it didn’t flower, but it seemed to take hold. I’m optimistic about seeing some of the orange flowers next summer.

Butterfly weed, not as easy as I'd hoped.

    I also started seeds of common milkweed (Asclepias syriacus) and planted a couple of seedlings. This could turn out to be a mistake, because the plant is reputed to be quite a spreader. I like the seed pods and the seeds with their parachutes of white fleece, though, and I’m hoping to see some monarch caterpillars on the leaves.

Common milkweed seed pods opening in fall

    As an experiment, I laid a half-open common milkweed pod that I found in the neighborhood on the ground in an open area near some new shrubs. Maybe the wind will pick up some seeds and sow them as it would in the wild.

    I spotted just one monarch butterfly in the yard this summer. I hope she or he will send friends.