global warming and yer garden

[Guest guest]

y Constance Casey

Posted Wednesday, Feb. 28, 2007, at 12:20 PM ET

http://www.slate.com/id/2160830/pagenum/all/#page_start

 

A garden at the Denver Botanic GardensThe hardly-any-water-at-all

garden at the Denver Botanic Gardens

Lilac bushes in New England have pretty steadily been blooming earlier

every year for the past 30 years. One way some gardeners have begun to

think about shorter winters is to say, " Hey, great, I live in Ohio [or

wherever, north of the Mason-Dixon Line] and now I can grow some

camellias, maybe a fig tree. " This is, frankly, nuts. Be careful what

you wish for. Kudzu is creeping north, poison ivy is growing more

toxic on its diet of extra carbon dioxide, and allergy season lasts

longer.

 

Another reaction is to say, " I will make the world greener by planting

a tree in my front yard that will inhale carbon dioxide and slow

global warming. " This is not nuts, and it's better than nothing,

especially if you are planting a shade tree on the south side of your

house and thus cutting your air conditioning use. But in the face of

the enormity of global temperature change, it's only a little bit

better than nothing.

 

There are two very specific and more sensible ways to prepare than by

cheerily planting the flora of Charleston, S.C., in Cleveland. First,

insulate the green things you have from the shock of drought to come

by making the soil they live in better at holding on to moisture.

Next, choose new plants that can tolerate drought and a wide range of

temperatures.

click here

 

The institutions that guide gardeners have themselves started to

adjust. The Arbor Day Foundation recently released a hardiness zone

map. Their members complained that the widely used official government

source-the U.S. Department of Agriculture map-didn't reflect how much

the country was warming up.

 

The Arbor Day Foundation map, using the USDA Hardiness Zone Map of

1990 as a starting point, tracked some dramatic changes from then to

2006. Our heartland-Illinois, Indiana, Ohio, and even Michigan's mitten

-has shifted from Zone 5 to a warmer Zone 6. (Higher temperatures mean

that most U.S. gardeners will be facing longer summer stretches

without water.)

 

The USDA, slower off the mark, will release its own update of the 1990

map sometime this year. When asked if the forthcoming new map was a

response to global warming, USDA spokesperson Kim Kaplan said, " Not

specifically. " She gave as more compelling reasons the fact that the

Government Printing Office is out of copies of the last version and

that the old version wasn't Internet-friendly.

 

Both maps divide the United States into zones by shared average low

temperatures. Bands of different colors run from a very cold Zone 1

(Fairbanks, Alaska) to a tropical Zone 11 (Honolulu). The maps are a

general guide; you may have something like a sunny wall where cold-

averse plants can grow. Or your garden may be in a valley that's

colder than the surrounding hillsides.

 

For those who acknowledge that warming is definitely here, the highest

priority is to protect trees, which shelter other plants from drying

wind and sun, as well as absorb carbon dioxide. The single best

drought-survival help you can give those beneficial trees and your

other plants is to cover any bare earth, from which water evaporates

quickly, with mulch. Spread shredded bark or bark chips or compost

about 3 inches deep on top of the soil (take care not to push mulch

right up against plant stems or tree trunks where it can cause rot).

 

When you're planting new things or moving old plants, improve the

moisture-holding capacity of your soil even more by digging in organic

matter-the same bits of bark or well-rotted cow manure, or compost.

 

Compost-dark, earthy, decomposed organic matter-has the immediate and

obvious effect of making your soil moister, and it's also a welcoming

home for the earthworms and microorganisms that make nutrients

available to your plants.

 

A less obvious effect of making and using compost is to keep the

atmosphere healthier. When the stuff rots in a municipal landfill,

instead of decomposing in a nicely aerated compost heap, it exudes

methane-a greenhouse gas that traps heat on Earth at a greater rate

than carbon dioxide does.

 

Selecting plants for drought tolerance doesn't mean that your yard

will be all yucca and cactus. Lots of favorite annuals bloom well with

low water-cosmos, petunias, verbena, marigolds, and zinnias. (Remember

that even drought-tolerant plants need to be watered thoroughly when

they're first planted.)

 

Perennials from Mediterranean climates have evolved to thrive without

summer rain. Pinch the leaf of a plant native to Provence or Greece

(and similar climates in coastal California, South Africa, and Chile),

and you'll see these plants are resinous and fragrant. These include

useful and beautiful plants like lavender, rosemary, sage, catmint,

oregano, and thyme. A less familiar herb-agastache, also known as

hyssop-is a real garden star; it flowers nonstop through the summer,

beloved by bees. The red agastaches attract hummingbirds.

 

The Denver Botanic Garden, which has long been landscaping with

natives adapted to Colorado's semi-arid climate, has clear advice and

useful plant lists. The catalog of High Country Gardens in Santa Fe,

N.M., has particularly interesting water-smart planting designs

including " The Inferno Strip Garden " -for hot, narrow spaces.

 

Any botanical garden will have good advice on the native plants that

can stand up to hot summers; planting natives will make life easier

for your local birds and beneficial insects.

 

Like everything involved with interacting with the natural world,

water-wise gardening gets a little complicated. Climate watchers who

are warning us of longer droughts also are predicting heavier rains in

winter, coming in fewer events-downpours, buckets. The plants from the

Mediterranean or the Colorado high plains do not do well if their

roots are drowned. Happily, and also paradoxically, a good cure for

waterlogged soil is to add organic material. It's an apparent paradox

because that's the stuff that holds on to water, but the organic stuff

also keeps the soil aerated and keeps water from collecting in fatal

puddles.

 

You can hedge your bets in this chancy new world by choosing trees and

shrubs that do well across many temperature zones. Among the most

adaptable: oakleaf hydrangeas, amelanchiers, many of the deciduous

magnolias, and a lot of the pines. It may not be precisely right, I

suddenly realize, to use the word adaptable. People are adaptable; we

can change our behavior. (Not long ago no one used car seatbelts, and

everybody smoked.)

 

It's more accurate to say that some plants and trees have evolved to

tolerate or survive or withstand a range of conditions. There are some

clever little weeds that can shift strategies quickly, but for the

most part it takes generations for trees to adapt to new conditions,

which makes them terribly vulnerable.

 

The tree losers in the coming warming, sadly, are sugar maples and

white birches, which thrive in a niche and are unwilling to adapt.

Their populations are dwindling in the warming Northeast, land of the

precocious lilacs.

 

Gardeners tend to be the most adaptable of human beings. In fact,

working in a garden is an experience that trains you to be flexible

and to find consolations where you can. So the poppies never came up

and deer ate the roses? Well, the irises looked great, and the lilacs

were fabulous.

 

 

" NOTICE: Due to Presidential Executive Orders, the National Security Agency may

have read this email without warning, warrant, or notice. They may do this

without any judicial or legislative oversight. You have no recourse nor

protection save to call for the impeachment of the current President. "