Using a plant-hardiness zone to determine which plants will thrive in any region has long been a tool of the plant-wise
gardener. Today, however, as we become more conscious of evolutionary changes in the weather, tools such as water-thrifty
gardening, the use of native habitat and gardening without chemicals or pesticides are fast becoming a way of life.
Still, more tools can help us wade through the piles of data and resources available,
with the end goal of ensuring that our plants will be healthy and thrive in spite of changing weather. One such tool is the
book, “Heat-Zone Gardening,” by Dr. H. Marc Cathey and Linda Bellamy. A colorful, 192-page text, “Heat-Zone
Gardening: How to Choose Plants That Thrive in Your Region’s Warmest Weather” offers an overview of gardening
in the 21st century, as well as tools for choosing climate-adapted plants, gardening in any one region in particular, and
effective watering techniques.
Cathey, a renowned research horticulturist,
is president emeritus of the American Horticultural Society. The book was co-written by journalist and garden writer Linda
Bellamy, whose work has included contributions to The Washington Post, Garden Design and the Time-Life Complete Gardener book
series. The purpose of this book is to help our plants succeed even through sudden unseasonable breaks in the weather—be
they hot or cold.
“Cold hardiness… is only one factor
in a plant’s chance of survival,” states the author, who adds that today’s gardener must recognize that
summer heat can be just as devastating as winter cold snaps. “Global warming—the gradual heating up of the earth’s
atmosphere due to an increase in atmospheric carbon dioxide—holds an obvious significance for gardeners everywhere,”
according to Cathey.
He notes that while global warming seems slow
to progress in our lifetime, the changes that have already occurred are dramatic. For example, “five of the 10 hottest
years ever documented have occurred since 1990, with 1995 breaking all heat records for recorded weather history.” To
the conscientious gardener, that means a gradual loss of winter. The frost-free season now begins approximately one week earlier
than in the past, states the author. Longer heat waves or periods of drought, as well as concerns about diminishing water
supplies, have left people across the country more concerned than ever about how to preserve existing resources. “Wherever
you live ... waterside, heat-tolerant garden design makes good gardening sense,” Cathey says.
response to environmental concerns, the American Horticultural Society has published a Plant Heat-Zone Map, and may continue
to provide updates as evolutionary changes create new weather patterns nationwide. This up-to-date map indicates the longest
periods of heat that gardeners can expect for their region.
Washington, for example, depending on exact location, we can expect to see probably no more than 14 to 30 days with a temperature
in excess of 86 degrees F. Southern Texas, Florida and Arizona might expect as many as 210 such days per year. The authors
recommend combining this map with the standard hardiness-zone map provided by the U.S. Department of Agriculture. Such a combination
will help home gardeners to select plants that may then live for years, adapting to excesses in either cold or heat.
Although it’s highly technical, the book is not difficult reading. And as
easily as he talks about global warming in one instance, in the next he easily reverts to a poetic interpretation of gardening
for all seasons. “Nature writes. Gardeners edit,” said Roger Swain, as quoted in “Heat-Zone Gardening.”
Cathey goes on to say that “thoughtful planning (and) a bit of old-fashioned hard work,” as well as ingenuity,
are key ingredients for any successful garden — be it in Texas, Savannah or Manhattan.
use of doors, arbors, or other existing landscapes of all kinds can be immensely helpful, he writes, in creating the perfect
microclimate for the plant in question. A marginally hardy fruit tree, for example, might do well in a sheltered spot near
the home — whereas elsewhere, it might simply fail to prosper.
another quote, he points out the value of designing gardens to match the climate. Michael Pollan said, “As soon as someone
decides to rip out a lawn, he or she becomes perforce, a gardener, someone who must ask the gardener’s questions: What
is right for this place? What do I want here? How can I go about creating a pleasing outdoor space on this site? How can I
use nature here without abusing it?” Fundamentally, any gardener looking to “use nature without abusing it”
will find many answers in this book.
More than half the text is
devoted to plant profiles, offering specific cultural information. Cathey quotes Vita Sackville-West when he begins the section
that features more than 450 plants. She once said: “Flowers really do intoxicate me.” If flowers intoxicate you
and you care about your plants’ long-term success, you’ll want to consider “Heat-Zone Gardening” as