What plant zone is ma

Microclimates: Planting Beyond Your Hardiness Zone

Crape myrtle is a flowering tree grown in the South, with large pink or white flowers hanging from the ends of its branches in midsummer. For years, a deep pink crape myrtle grew on the corner of Worcester Court and Route 28, in front of what is now TD Bank. Granted, it was more shrub than tree, yet it was always a reliable sign of August.

Sadly, the last time I checked, it was gone. Perhaps it’s still there, and I’ve missed it, or it succumbed to the cold one winter. No matter, I know crape myrtle can survive on Cape Cod.

Camellias can live here, too, even reaching the size of trees. A customer at the garden center where I worked grew them on his property in Brewster, adding to his collection by buying the camellia varieties we sold as house plants. Some years, he said, they’d get battered by the cold, their evergreen leaves sporadically brown from frostbite, yet they still survived and bloomed.

I’ve heard rumors about edible figs and pampas grass, although I haven’t seen them with my own eyes.

The reason some southern plants make it through the winter has to do with the Cape’s propensity for microclimates. A peninsula surrounded by water, such as ours, experiences more moderate temperatures than inland areas. Factor in the proximity to the ocean and a yard two streets away from the water can have crape myrtle while a yard a block away cannot.

Further, microclimates have no defined size; they can be as small as the area next to a house—ideal for tender perennials such as verbena to winter over.

Whatever the area, a microclimate flies in the face of a location’s designated hardiness zone.

Cape Cod and the Islands are shaded a light pink on the USDA Plant Hardiness Zone Map, translating to Zone 7a on the key. It may be hard to spot this fact on the colored swirls spanning the United States and Canada, but 7a it is. Our lowest temperatures, according to the map, range from 0 to 5 degrees Fahrenheit. Parts of Maryland, Virginia and North Carolina are in the same bracket.

I don’t know about where you live, but at my house it’s been 10 below many winters, which answers the question why the camellia I planted one year didn’t make it.

Crape myrtle is hardy from Zone 7a through Zone 9, as are camellias and edible figs. Shouldn’t these plants be reliably hardy on the Cape? Why don’t we see more of them here?

Having seen crape myrtles everywhere in Baltimore and a couple of mature edible figs growing near the Chesapeake Bay, I can tell the difference. The crape myrtles there are at least 10 feet tall and used in the landscape in the same manner we use rose of Sharon. The edible figs look as established as old rhododendrons.

Perhaps the difference has to do with latitude. South means hotter summers and more moderate winters than the Cape experiences. Crape myrtles are glorious during the hottest months of the year. The figs were bearing ripening fruit.

According to the National Arboretum in Washington, DC, an established crape myrtle can die back to the ground during a cold winter, then leaf out again from the base like a perennial, or the tree can die altogether. This may have happened to the crape myrtle in Falmouth.

Despite the risk, perhaps southern plants are worth a try. The National Arboretum lists hardier varieties of camellias and crape myrtles. Figs will probably need to be brought inside. And pampas grass? I think the Cape isn’t hot enough.

Global warming is said to be changing hardiness zones. I won’t attempt to discuss such a complicated subject. Let’s just say Florida still can’t grow tulips without providing an artificial winter and we can’t grow palms, although I’ve heard there’s a hardy banana. You never know what the garden can hold.

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How Regional Gardening Works

Successful regional gardening hinges on knowing what plants are suited for your zip code’s climate. What flourishes in Boston may wither in Fresno, Calif., or Cheyenne, Wyo., since the cities don’t share identical growing conditions. Or the same plant could require different levels of care in different locations. To help us know what plants will thrive in our backyards, the U.S. Department of Agriculture (USDA) devised a cheat sheet, called the Hardiness Zone Map. Most plants you buy come with a reference tag that details optimal sunlight, season and watering schedule. Plants may also have a number listed beside a color-coded map of the United States. That number and map refer to hardiness zones.

­The USDA’s map divides the United States into 11 hardiness zones. Hardiness zones, numbered one through 11, denote the lowest temperature ranges typical for that region and are ranked from coldest to warmest. Neighboring zones are 10 degrees higher or lower than each other. All zones, except for 1 and 11, also are split into “a” and “b” subregions, which are separated by 5 degrees. Why do hardiness zones only measure cold extremes? Plants are more sensitive to cold than heat.


For example, peonies grow in hardiness zones 3 through 8, which means the flowers can withstand cold temperatures from 20 to minus 40 degrees Fahrenheit (minus 6.6 to minus 40 degrees Celsius). You can feasibly plant them if you live in Austin, Texas, since your plant hardiness zone would be 8b. In normal weather, the mercury should drop no more than to 15 or 20 degrees Fahrenheit (minus 6.7 to minus 9.4 degrees Celsius). But you’d have to leave them behind if you moved to chilly Pinecreek, Minn. There, the hardiness zone is a 2b, and it could reach minus 45 to minus 40 degrees Fahrenheit (minus 40 to minus 42.7 degrees Celsius).

When using the hardiness zones as your gardening guides, remember that it applies only to perennials. Annual plants die at the conclusion of their growing seasons, rendering the zone distinctions irrelevant. The USDA hardiness zone map also isn’t flawless. Its accuracy varies depending on your location. If you live in the flatter geography of the Eastern and Plains states, the zones are fairly reliable. But as you travel west, the map skews somewhat because of the mountainous geography. The interaction of the higher elevations and weather moving eastward from the Pacific Ocean outweighs the influence of temperature on plants .

In addition to cold temperatures, a gardener must consider factors such as water, light, ambient temperature and soil acidity. As with hardiness zones and climate, those elements will shift as you move among gardening regions.

The USDA Plant Hardiness Zone Map – Changes in the 2012 Edition

The USDA Plant Hardiness Zone Map – Changes in the 2012 Edition

Knowing their Plant Hardiness Zones helps gardeners to decide which plants are likely to survive through the winter in their particular location. The United States Department of Agriculture (USDA) created the first map of these hardiness zones in 1960, dividing the US and Canada into 10 zones, representing 10 degree differences in average annual minimum temperatures between each zone. The higher the zone number, the warmer it tends to be in that area. The USDA updated the map in 1990, basing the zones on weather data collected between 1974 and 1986. For this version, they also created the 5-degree half-zones, denoted “a” and “b”, for greater accuracy.

In 2012, the USDA released a new and improved version of its Plant Hardiness Zone Map. The data used to create this map was collected over a 30-year period, between 1976 and 2005. According to a news release from USDA’s Kim Kaplan, “for the first time, the new map offers a Geographic Information System (GIS)-based interactive format and is specifically designed to be internet-friendly. The map website also incorporates a ‘find your zone by zip code’ function. Static images of national, regional, and state maps have also been included to ensure that the map is readily accessible to those who lack broadband internet access. The new version of the map includes 13 zones, with the addition for the first time of zones 12 and 13. Each zone is still a 10-degree F band, further divided into 5-degree F zones ‘a’ and ‘b’”.

The zones in this most recent edition of the map have shifted slightly since the 1990 version. Most areas are now categorized as one 5-degree F half-zone higher. That is, their average annual minimum temperatures were found to be somewhat warmer than when the 1990 version was published. This is largely due to the fact that more recent temperature data, collected over a longer period of time was used. Some changes, though, also result from the use of more sophisticated data-collection tools and methods. According to Kim Kaplan, “These include algorithms that considered for the first time such factors as changes in elevation, nearness to large bodies of water, and position on the terrain, such as valley bottoms and ridge tops. Also, the new map used temperature data from many more stations than did the 1990 map. These advances greatly improved the accuracy and detail of the map, especially in mountainous regions of the western United States.” In some cases, areas were found to be cooler rather than warmer.

Zone numbers in the continental United States range from 3a in northern Minnesota and 3b in northernmost Maine, to 10a at the southern tip of Texas, 10b around Los Angeles and 11b in Key West, Florida. Zones in Massachusetts range from 5a in the Berkshire mountains to 7a on Cape Cod. Most of western Massachusetts is in zone 5b, while most areas in coastal eastern Mass are now designated as zone 6b, where the average annual extreme minimum winter temperature is between 0 and -5 degrees F. Gardeners who live in 6b should be able to grow plants that are hardy to zone 6, as well as any plants whose zones are numbered lower than that (zones 5,4,3,2). These zone 6 gardeners might be challenged to grow plants that are hardy to zone 7b (avg. min. 5 to 10 degrees F) as those plants may not survive in the colder zone 6.

It is important to remember, however, that within each garden location “microclimates” exist which may allow gardeners to grow plants that may be listed at a higher zone number. For example, in a zone 6 garden, there may be a warm, sunny location, with well-drained soil, near a building that is protected from the cold and wind, making that particular location a “zone 7”. Conversely, in that same zone 6 garden, there may be an open, unprotected, low-lying area, where cold settles, making that a zone 5 area, an area where zone 6 plants would struggle.

Access the 2012 USDA Plant Hardiness Zone Map here: http://planthardiness.ars.usda.gov/PHZMWeb/

-Adapted by Lisa McKeag from an article by Deborah C. Swanson, Horticulturist, UMass Extension/Plymouth County, RETIRED, with source information from press release USDA Unveils New Plant Hardiness Zone Map by Kim Kaplan, USDA

Massachusetts Planting Zones

The state of Massachusetts has mostly a humid continental climate and when it comes to Massachusetts planting zones, there are just two. It has cold and snowy winters and warm summers. A popular region known as the Berkshires has cooler temperatures all year long, while the coastal region tends to be warmer. Summer highs average right around 80 degrees in the hottest months, and winter lows average about 16 degrees with considerable snowfall. Along the coast, winters are less extreme with temperatures remaining above freezing even in January, when the inland areas of the state are much colder.

Massachusetts growing zones fall somewhere between 5a and 7b. Growing zones, also known as plant hardiness zones, are a way of identifying what plants will survive and do well in certain areas. Find your Massachusetts growing zone quickly and easily on Gilmour’s Interactive Planting Zone Map. Growing zones help determine not only what to plant, but also when to plant it. Using first and last frost dates as a guide, each zone will specify when to put plants in the ground. Massachusetts planting zones vary depending on how far inland you are in the state, with the more western-reaching parts of the state seeing extreme cold and more volatile winters and planting zones between 5a and 5b. When planting a garden, keep in mind that anything rated for the zone you are in or lower should be able to survive winters. So, for example, in the coldest parts of the state that are planting zone 5a, plants rated anywhere from zone 1 through zone 5 will likely be fine.

Plants and flowers that do well in Massachusetts are wide-ranging, so whatever look a gardener is going for is likely achievable. Hostas, many varieties of ferns and sedums are all striking perennials that do extremely well in this region. Echinacea (also known as purple cone flowers), black-eyed Susans, daylilies and Siberian Irises are blooms that thrive here. If planting a summer vegetable garden, root vegetables like potatoes love the Massachusett planting zone conditions, as do carrots. Note that sweet potatoes do not do as well here since they need a warmer and longer growing season. Corn, lettuce, beans, tomatoes and peas are other veggies that will produce plenty. And brassicas (cabbage, Brussels sprouts and broccoli) love the cooler temperatures and rich moist soil, making them ideal to grow in a seasonal Massachusetts garden.

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