New plant hardiness zone map adjusts for warmer temps

betsjukofsky@aol.comJuly 8, 2012 

  • The new Plant Hardiness Zone Map is available at

This past winter has made a liar out of me.

At an early spring meeting with the Beaufort Garden Club, I was asked if I had a favorite wildflower. I didn't hesitate to answer. It's scutellaria integrifolia and here's why: "Skullcap" is showy. It has a slender stalk with small blue flowers framing tiny white "faces."

Best of all, I told them, it flowers in late summer, a time when few other wildflowers bloom.

That is, it did until this year when they were up and out of the ground in March and in bright blue bloom in May.

Soon, they were joined by other "autumn" and "mid-summer" bloomers: the wildflowers, Tickweed (Verbesina virginica) and Ruella Carolinians.

What is going on?

As I write this, much of the nation is undergoing a hot spell that is setting records. This would seem to reflect a warming climate.

The good news is that the USDA people are right on top of it: The new Plant Hardiness Zone Map is being released -- its first update since 1990. The map shows a 5-degree half-zone movement northward over much of the country. It covers 13 zones instead of 11.


It's time for me to get out of my yard and visit Heritage Farm with its many individual gardens and gardeners who are growing ... well, let's just say, if it grows in our zone 9, they are growing it. I called my friend Rosemary Kimball, publicity chairwoman for Heritage Farm, who met me and introduced me to John Witherspoon, the farm president. I asked them both a few questions:

Question. John, I understand you are overseeing 11 acres here. Any problems?

A. Oh, yes. The big crisis this year were the deer. They broke into our electric fence. It only takes one brave, strong buck to start the hole. Others soon follow. We needed to replace 40 posts. We held an oyster roast and raised $3,000. I see another crisis looming. Besides our best efforts we've had to restrict water usage because our water rates have increased dramatically.

Q. How does that work with the automatic water timers?

A. We don't permit water timers. I'm in touch with the folks at Seabrook Farm on Hilton Head Plantation and what they have and we don't is a well. Example: We used 520,000 gallons of water in five months; farmers at Seabrook at the same time used 3 million.

Q. Are you still raising vegetables to donate for Deep Well as you've done for many years?

A. Yes. Each year we give 3,000 pounds to Deep Well. The Greenery Nursery donates the vegetable plants that we grow.

Q. Rosemary, as a kind of cheerleader for all of these farmers, what do you see as a problem this season?

A. It's whatever is attacking the tomatoes. John has dug out a worm that looks like a caterpillar but is brown. It makes a clean hole in the fruit that destroys it. We are picking our tomatoes green, and still flawless, and taking them home to ripen.

Q. Over the years when I've visited here, I've made a point to see John McHugh and his garden. Is he here now?

A. No, but I'll show you his garden. He grows too many veggies for his use; he takes the excess to Tidepointe, where he lives, to give to friends. His garden is organic; he uses organic soil enriched with spaghum moss.

Q. Can you show me your garden?

A. All of my tomato plants are Big Boy. I've lost only one. I've a great crop of carrots. I feed Harley, a Clydesdale, who comes to the fence when he sees me coming and eats carrots with foliage out of my hand.

Q. You have many beautiful roses and other flowers. Do they need special care?

A. The roses do. Despite spraying with Sevin and feeding with Miracle-Gro, I can't seem to rid them of black spot. The zinnias are the easiest and best flower to grow here. These are all from seed. The black-eyed Susans are perennials that come back each year. Let me take you to see the most beautiful garden here. It's all flowers and is tended by Eleanor Hathaway, a beautiful woman, who works it four hours a day, almost every day.

On the way out we stopped at Mary Gumerman's vegetable and rose garden. We sat in the shade of a large arbor and watched the butterflies and bees around Mary's favorite white roses. Driving home, I reflected on how happy I feel when I've visited with gardeners in their gardens; this peacefulness lasts all day.

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