Horticulturist explains new USDA plant hardiness map

February 16, 2012 By Lois Stack

The recently released USDA Plant Zone Hardiness Map, updating the previous 26-year-old zone map, reflects rising mean temperatures throughout the country, including Maine, where gardeners must carefully consider possible temperature dips as they anticipate spring planting.

University of Maine Cooperative Extension professor and ornamental horticulture specialist Lois Berg Stack is available to explain what the new map might mean for Maine gardeners, in addition to suggestions about preparations for early planting.

The hardiness zone map has always been a suggestion for plant selection, not a guarantee, says Stack. Lots of other factors – length of growing season, accumulated heat during growing season, water availability, nutrient availability, soil type, general plant maintenance, etc. – are equally important.

“I usually tell people that the hardiness zone rating is a starting point,” she says. “And, although we do have climate change, and the new reflects some ‘warming’ in some parts of Maine, it is based on one thing: the single coldest each winter, averaged over several years. have to survive each day, one by one. Although our winters may be warmer on average, we still have cold temperatures every winter.”

Stack also says that February is the start of the gardening season – the time to start onion seeds for next winter’s storage, time to take cuttings of geraniums that have overwintered on a windowsill, time to visit a local garden center to for inspiration, or the time to take a gardening course or read a gardening book.

February also is the perfect time to cut tree and shrub branches to bring indoors to force their flowers into color, she adds.

Explore further: Cornell patents a pink lily look-alike that blooms all summer long

Related Stories

Maine weather wreaking havoc on deer

March 30, 2008

Deer living in Maine and other portions of New England are likely battling starvation because of the region's tough winter, biologists say.

Keep It Growing -- Plant Fall and Winter Vegetables in July

July 14, 2008

(PhysOrg.com) -- In mild parts of western Oregon and along most of the coast, it is possible to grow a succession of garden vegetables throughout the year. You can extend the season well into fall in many parts of the Pacific ...

Fight droughty dullness with cool-season euphorbias

October 31, 2011

Find the lack of fall colors this year depressing because of the drought? Texas Superstars newest selections, cool-season euphorbias, can brighten up landscapes throughout the winter, said a Texas AgriLife Extension Service ...

New eco-friendly foliar spray provides natural anti-freeze

December 14, 2011

Cold-weather garden enthusiasts have a new reason to celebrate. Researchers at The University of Alabama and Miami University of Ohio have introduced an innovative, all-natural foliar spray that protects plants, both externally ...

New map for what to plant reflects global warming

January 25, 2012

(AP) -- Global warming is hitting not just home, but garden. The color-coded map of planting zones often seen on the back of seed packets is being updated by the government, illustrating a hotter 21st century.

Recommended for you

New gene map reveals cancer's Achilles heel

November 25, 2015

Scientists have mapped out the genes that keep our cells alive, creating a long-awaited foothold for understanding how our genome works and which genes are crucial in disease like cancer.

Study suggests fish can experience 'emotional fever'

November 25, 2015

(Phys.org)—A small team of researchers from the U.K. and Spain has found via lab study that at least one type of fish is capable of experiencing 'emotional fever,' which suggests it may qualify as a sentient being. In their ...

How cells in the developing ear 'practice' hearing

November 25, 2015

Before the fluid of the middle ear drains and sound waves penetrate for the first time, the inner ear cells of newborn rodents practice for their big debut. Researchers at Johns Hopkins report they have figured out the molecular ...

How cells 'climb' to build fruit fly tracheas

November 25, 2015

Fruit fly windpipes are much more like human blood vessels than the entryway to human lungs. To create that intricate network, fly embryonic cells must sprout "fingers" and crawl into place. Now researchers at The Johns Hopkins ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.