PITTSBURGH (KDKA0 – The last two winters have been really hard on our plants and gardens, and the harsh cold has come as a shock to many of the items we like to have traditionally grown in southwestern Pennsylvania.

“We had so many nice mild winters that all those zone six plants and almost into zone seven plants were surviving,” says Doug Oster.

Oster is the Back-Yard Gardener for the Pittsburgh Post-Gazette, has published numerous books on the topic, and is the co-host and producer of The Organic Gardener on KDKA Radio on Sunday mornings.

“Last year, after the Polar Vortex, when people called me and said their ivy was gone, I said, ‘It will come back. It will come back. It always does.’ But, a lot of it didn’t.” says Oster. “I think it’s just an anomaly over the last two seasons. I wouldn’t be afraid to plant ivy. It really is tough as nails.”

This weekend, thousands of gardeners will be picking out plants and putting them in the ground over Memorial Day.

When you go, look for the USDA Zone Guide at your local nursery or garden center. Oster says it can make your plant buying decisions a little easier this spring.

“There’s a map the USDA puts out. We’re called zone six. North of us is zone five. South is zone seven. So, all our plants — shrubs, trees, perennials, plants that come back year after year — have that number on them.”

The tags are pretty self-explanatory. In addition to showing the sun/shade requirements, the tags also show the zones where the plant will thrive — and they often include notes about temperature extremes.

“When you do come to the nursery, take a close look at the plant, read the tag, be sure that you know how hearty it is, and talk to the people at the garden center and see is this really a tough variety, or have they lost this over the last two winters,” Oster says.

Oster says zone designations are not reserved for plants already out of the ground.

“There are some tender bulbs — so things like daffodils and tulips that would probably be zone four, no problem. You get into some other plants that might be for warmer climates, we are not sure if they will winter over yet,” says Oster.

How can you tell if one of the plants on your property isn’t going to make it? Oster claims there is one simple test.

“Go to one of the branches and just try and bend it. If it is still supple or you scrape it with your fingernail or a pocket knife and you see green, it’s still alive,” he says.

What does it mean if it breaks easily?

“If it snaps right off, it’s dead,” Oster says. “Dead is dead, and all deadwood has to be removed from plants.”

Then make a mental note about that plant and whether you want to put it in your garden again.

“I am being more careful with what I am planting. I am not going into zone six. I am basically staying with zone five plants,” he says.

However, despite his own best advice, Oster is making one exception.

“I have two roses that I lost, but I love them so much, and they went 15 years. So, I am replanting them and just hoping for the best. I love the plants so much that I am going to give it another try,” he says.

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