PBS NewsHour highlights challenge of warming winters for tree planting

The new release of hardiness zone maps from the USDA has certainly piqued the interest of the adventurous gardener. As USDA data shows – and the Arbor Day Foundation similarly corroborated in 2006 – the uptick in lowest minimum winter temperatures in much of the country has shifted the landscape.

Many of these changes are highlighted in a new blog post from the PBS Newshour.

Chihuahuan desert plants are expected in rural New Mexico, for instance, but now they’re making an appearance in the more-elevated Santa Fe, writes Rebecca Jacobson. And wine-makers in Virginia are happily experimenting with new crops.

There is another side to the coin, however. Warmer winters also mean pests that used to be killed off by the cold survive into spring.

In Ohio, fungi are latching onto the Colorado blue spruce tree (above) for longer periods. Virginia, while ripe for experimentation, has seen bacterial infections choking grapes. Beetles and other insects are also thriving in the warmer weather, destroying crops and trees, writes Jacobson.

How are we to assess these zone changes? That depends a lot on where you’re standing, or where you tend your backyard. But like any change in the climate, it comes with myriad consequences, some of which we may not notice right away.

You can read more about the new USDA maps here, and check out our online nursery here.

New hardiness zone maps reflect rising temperatures, and trees are part of the solution

For years, Arbor Day Foundation members have told us the climate conditions for tree planting were changing. According to last week’s release of new plant hardiness zones from the U.S. Department of Agriculture, they’re right.

A hardiness zone documents the average lowest winter temperature in a given region. This is key information for growing, as it determines what level of cold-related stress a tree can handle.

The official map was long overdue for an overhaul. Those who had relied on the USDA’s 1990 map found it to be severely out of date, prompting the Arbor Day Foundation to produce its own map in 2006 to more accurately reflect conditions in backyards and neighborhoods across the country.

The shift, for most of the country, is palpable. A comparison between the USDA’s 1990 map and the Arbor Day Foundation’s 2006 map reveals large swaths of the country moving up a zone (see below) The new 2012 USDA map broadly resembles what the Arbor Day Foundation map indicated back in 2006.

Here in Nebraska, most of the state used to be in Zone 4 but is now in Zone 5, signifying a shift in the interval of coldest average temperature from between -30 and -20 to between -20 and -10 degrees Fahrenheit. Zone 11 used to be limited to Hawaii, but now can be found in parts of Southern California and Florida.

While a shift by one zone doesn’t always have a huge impact on what can grow, it definitely matters at the margins. For instance, the Yoshino Flowering Cherry Tree, a favorite in Washington, DC’s Cherry Blossom Festival, is recommended for hardiness zones 5 through 8. Colder areas like New England and the upper Midwest that shifted from Zone 4 to Zone 5 can now conceivably plant Yoshinos in their backyards. (You can also purchase your own cherry tree – and cast your vote for America’s Favorite Cherry Tree).

Another example: The Southern Magnolia thrives in Zones 6 through 10. Twenty years, it could not have grown in most of Ohio, Michigan and Pennsylvania, but now it can be considered by an adventurous tree planter in his or her yard. Or, take the Arizona Cypress, a zone 7 through 9. Now it is now a viable choice in much of New Mexico and Texas.

The warming indicated by the new map has inevitably renewed discussion about climate change. This is a worthy topic, especially as trees are acknowledged as part of the solution.

When we plant trees in our yard, they immediately go to work for us. The shade provided by trees during hot summer days not only makes life more comfortable, it also reduces the energy consumed through air conditioning by as much as 40 percent. In winter time, well-placed trees can block bitter winds, resulting in reduced energy use from heating. And, a parking lot with 50 percent shading can eliminate one ton of emissions per day, while extending the life of the pavement.

When households demand less energy, we save precious resources and reduce the greenhouse gas emissions that contribute to climate change because utility companies save energy during periods of peak demand. When mature trees absorb carbon dioxide in urban areas, harmful pollutants are removed from the atmosphere and are naturally regenerated.

Many Americans are excited to explore new species of tree previously untenable in their region. Purchasing and planting trees is also a low-tech and low-cost way to mitigate an enormous environmental challenge.

You can check out the USDA’s updated map, or visit the Arbor Day Foundation’s online nursery and simply enter your zip code to see what trees are a good fit for your area.


If you should ever find yourself luxuriating in the French Riviera, and in the unlikely event you grow tired of the sand and sea, a walk in the hills will introduce you to the unique woodlands of the Mediterranean.   There, among the scrubby oaks and umbrella pines you will find a familiar bush or small tree, the European smoketree – in its native environment.

There are only two species of trees in the genus Cotinus.  One is the American smoketree, the other is its close relative from Europe.  For both, their claim to fame is the wispy clumps of filaments that look all the world like smoke.  The mirage has given rise to other names such as mist tree, cloud tree, wig tree, and Jupiter’s beard.  By whatever name, the site of this tree is what Minnesota garden writer Don Engebretson has called “one of the most arresting shrubs available to…gardeners today.”
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Dogwood: Beautiful Tree With Many Uses

Writer-naturalist Donald Peattie once wrote, “Lovely as it is, dogwood stoops also to be useful.”

What’s in a Name?

For all the beauty of this tree, the common name of dogwood may come from something less lovely – “dagger.”  This, in turn, may actually come from its early use as a skewer, or thin piece of wood used to hold meat together.  The tendency of its wood to not splinter made it popular for this purpose.

The scientific genus name, Cornus, derives from the Latin, cornu, or horn, in reference to another use of its hard wood.  The species name, florida, is also from Latin, flos, meaning flowery. 

Seasonal Color

The blossoms of dogwood add a welcome touch of color in early spring.  If space allows, the white can be accentuated with a background of conifers.  Bright autumn foliage and red berries that linger into winter add a bold stroke of color to any landscape design. Read more…

How to Beat the Summer Heat with Trees

Trees properly placed around a house can save you money and help cool your house in the summer.  This is according to the U.S. Forest Service Center for Urban Forest Research, but the concept is easy for everyone to understand.  Go outside sometime this summer and stand in the sun for a few minutes.  Then walk over to your nearest tree and stand in the shade.  I bet you will notice that the shade the tree provides is much cooler than standing in full sun.  This same concept can be replicated by planting trees in the right places to cast shadows on your house during different times of the day.  Find out where to plant around your house and what trees are best. 

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Before Planting a Tree, Call 811

Before reaching for that shovel to plant a tree, you need to call 811– the national number that connects you to your local call-before-you-dig center. This will allow you to get  the approximate location of buried utility lines marked. A recent Common Ground Alliance (CGA) survey revealed that homeowner digging projects will be up 10 to 15 percent this year compared to 2009, with tree and shrub planting at the top of the project list.


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