There’s been lots of news lately about the effects of climate change on our
gardens and oddly, it’s
usually presented as good news to gardeners. They’re
shown rejoicing over the warm-climate plants they can now grow, like crape
myrtles in Upstate New York. BUT:
IT'S GLOBAL WEIRDING
Some plants are failing because the winter cooling period isn’t long enough.
And others, like lilac, Eastern white pine, American arborvitae, Colorado blue
spruce, and many junipers, suffer when summer evenings don’t cool down enough.
Local garden writers are no longer recommending many of their old favorites for
local gardens - like PJM rhododendrons and yews.
- Rain events are more extreme, taking the form of longer droughts and more
deluges. Not good for landscapes, for agriculture or for plants in our few
remaining natural areas.
- Longer warm periods mean more generations of some pests per year. Others,
like the wooly adelgid that’s killing Canadian hemlocks throughout the East, are
increasing their number because winters aren’t cold enough to keep them in
check.
- Weedy and noxious plants, like poison ivy, honeysuckle and kudzu, thrive in
the presence of extra carbon dioxide, and poison ivy becomes more toxic than
ever. Ragweed produces more pollen. Kudzu moves north. Some weeds, like Canadian
thistle, are now resistant to herbicides.
- Native plant populations are threatened by these changes in temperature,
rainfall, pests and competitors, even the iconic ones chosen as state flowers
and trees. In fact, the National Wildlife Federation predicts that 28 states
will see their official plants become extinct by the end of the century. Picture
Ohio without its buckeye or Kansas without its sunflower. Climate change has
become a major threat to plant conservation, along with development and invasive
species.
- The East experienced a Miami-style January this year, followed by a frigid
February. These alternating balmy+frigid periods take their toll on blossoms and
whole plants. Fruit growers were particularly hard hit.
- Hotter summers cause heat stress even to warm-season crops, like tomatoes,
according to Cornell University.
MORE TO COME?
The life cycles of insects, including the beneficial ones that keep others in
check, may become out of synch with their prey. Pollinators, like the
disappearing honeybees, may already be out of synch with the plants they feed
on. Science Magazine reported in 2001 that earlier flowering and fruiting has
caused such a disconnect for some long-distance migrating birds, who depend on
food availability at the same time each year. And to make everything worse, most
climate modelers predict more flooding and drought.
Even English Gardens are Adapting
To see how gardeners might adapt to all this change, let’s look first at
what’s happening in England, a nation of gardeners. Last summer their southeast
region had such a severe drought that sprinklers were banned. With more and
longer droughts predicted, it’s clear that the very hallmarks of English
gardening are now threatened - their traditional lawns and flower borders.
Thus the U.K. Environmental Minister is urging everyone to change their water
usage, plant choice (look for drought- and heat-tolerance), and garden design -
in other words, change everything they’re doing. No more roses and delphiniums.
The use of gas-powered garden equipment is discouraged. Rain barrels are
recommended, as are carbon-sequestering cover crops, like clover and winter rye.
Brits are being given at least one bit of advise that fits their culture: plant
roots are darn good at absorbing carbon dioxide, so plant more of them.
CHANGING OUR GARDENING PRACTICES
Here in the U.S. we see the mainstream gardening media beginning to respond,
with both Martha Stewart and Better Homes and Gardens advocating less gas mower
and blower usage. Gardening authorities across the U.S. are offering these very
good suggestions: add organic matter to make your soil hold moisture better,
plant shade trees on the south side of your home to reduce air conditioning
loads, and do your planting in fall or early spring. Even turfgrasses can be
damaged by the freeze-and-thaw events we’re experiencing, especially where
there’s standing water, so we’re being told to fix our drainage problems.
CHOOSING DIFFERENT PLANTS
Research has really just begun, but here are the kinds of plants being
recommended by gardening experts in response to global climate change:
Perennials from Mediterranean climates, which thrive without summer rain.
Examples are such beautiful and useful plants as lavender, rosemary, sage,
catmint, oregano, and thyme. The herb agastache flowers nonstop through the
summer and is beloved by bees, and red agastache is a magnet for hummingbirds.
Locally native plants are particularly good for sustaining wildlife, but be sure
to ask for ones that will survive the new climatic conditions.
Choose trees and shrubs that do well across many temperature zones. Some have
seeds that can shift strategies quickly, rather than the generations it usually
takes for most trees to adapt to new conditions, which makes them so vulnerable
to climate change. Oakleaf hydrangea, serviceberries, deciduous magnolias and
many pines are especially adaptable to a range of conditions. Again, the science
is evolving, with experts at Cornell currently saying they haven’t yet seen
changes that cause long-term damage to trees and shrubs.
HOW GARDENERS CAN HELP REDUCE CLIMATE CHANGE
To borrow from one of the central tenets of organic gardening, the first goal
of gardening should be to do no harm. Here are some ways:
- Stop using gas-powered lawn equipment or products that use fossil fuels in
their production, like synthetic fertilizers. Gas mowers spew as much pollution
in one hour as a new car does in 40 hours - that’s how terrible the gas-mower
technology is. And those synthetic fertilizers can be replaced primarily by
compost and organic mulches, supplemented with organic, slow-release fertilizers
when an extra boost is needed.
- Instead of blowing leaves into plastic bags for them to be trucked away to
landfills or to an incinerator, turn them into soil, by composting. Home compost
operations help lighten pressure on landfills and result in more water-retentive
soil for the gardener - that really cool circle of life thing. Some
municipalities collect leaves and turn them into free leafmold mulch or compost.
- Grow your own food. It’s fresh, it’s as organic as you want it to be, and it
doesn't have to be trucked or flown in from far away. In the alternative,
frequent our local farmer’s markets.
- Finally, the quaint suggestion that we bring back a garden ornament from our
grandmothers’ gardens - the clothes line - comes from the Goracle himself.
ZONE MAPS - A HOT ISSUE
The last time the U.S. Department of Agriculture amended its famous map of
zones (bands of land that share the same winter low temperature), was 1990 and a
promised update has been delayed. One wonders why. Is it because, as a
spokesperson said recently on EarthBeat Radio, the mappers are in Iraq with
their tours extended indefinitely? Many suspect another reason - that the Bush
administration is trying to avoid documenting more proof of global warming. It
didn’t help that the USDA rejected the map update done for them by the American
Horticulture Society, and their explanations have been less than convincing.
>Fortunately, someone stepped in to fill the void.
The National Arbor Day Foundation recently released its own updated map, which
shows many places a full zone warmer than in1990, which means their low
temperatures are now 10 degrees warmer.
MORE GOOD INFORMATION ON LINE
Both Cornell
and the Brooklyn
Botanical Garden are excellent sources. And here's an overview of global
warming, carbon credits and the positive contribution made by organic
gardening.
Posted by Susan Harris
The road to stardom
c stumbled upon it in their search for a new host. (Not
surprisingly, since that demo's now been viewed 58,000 times, but how the heck
did that happen? I bet only insiders know the answer to that one.)
