So next time you see a plant you simply must have, check it’s hardiness zone; if it’s a zone up from yours, think about any microclimates on your property that might just be the perfect spot for it.

Have you ever lusted after a plant? You saw a picture of it in a catalog or a plant in your local nursery and thought, “Wow, I’ve got to have that plant.” The plant’s hardiness never entered the picture; you didn’t care whether it would survive our Michigan winters. You just knew you had to have that plant. So you bought it and planted it. Your plant was beautiful the first year. But it never came back after a Michigan winter.

Maybe you just didn’t plant it in the right spot in your yard, a place with a microclimate that better suits it.

Michigan is the largest state east of the Mississippi and the 11th largest of all the 50 states. It is 490 miles long and 240 miles wide at its most distant points. It offers gardeners a wide variety of growing challenges and has four United States Department of Agriculture (USDA) temperature zones.

The USDA has developed temperature zones based on how cold, on average, it gets in an area. (The USDA is revising their current map, which was published in 1990.) These zones help you pick plant material that will survive a Michigan winter. Today, most plants are rated with a USDA zone which helps the gardener save a lot of money by not planting perennials, shrubs and trees that will die off after one growing season.

Michigan’s four USDA zones with their average lowest temperatures are:

• Zone 6:0 to -10 F;
• Zone 5:-10 to -20 F;
• Zone 4:-20 to -30 F;
• Zone 3:-30 to -40 F.

To give you an idea of how diverse Michigan’s gardening climate is, it shares its zone 6 with Amarillo, Texas and its zone 3 with Anchorage, Alaska.

It is important to remember that the USDA hardiness zones are guidelines to use when selecting plant material. They are not absolute. Jeffrey Andresen, state climatologist at Michigan State University, comments, “Humans think of climate as being stable, but it is really dynamic. There is overwhelming evidence that Michigan is warming up.”

Studies are now showing the effects of cities on plant material. While your area maybe rated zone 5, if you live in a city surrounded by pavement which absorbs and holds heat, you may actually be living in a zone 6. These areas are called microclimates and chances are you even have microclimates, on your own property.

Microclimates can be either warmer or colder than your zone. Warmer microclimates would be areas sheltered from northerly and westerly winds by shrubs, fences and/or buildings, often located next to pavement or buildings. You can place an outdoor thermometer in an area which you think might be in a warmer zone on your property. Watch it throughout the winter to see if your hunch is correct. While doing this, keep in mind whether you’ve had a harsh or mild winter when deciding whether you have a true microclimate.

Or if you are a risk taker, you can dive in and place your semi-hardy plant material in a protected area and see how it grows and survives the winter. Just make sure that you’ve also met the plant’s requirements for moisture and light.

Make sure your microclimate area has good drainage, which allows for hardening off of woody shrubs. It is a good idea to mulch your semi-hardy plants to conserve moisture and minimize heaving of the ground. With semi-hardy perennials, the tops die back and only the roots need to be protected with a 6-inch layer of mulch. Just remember to remove the mulch as the sun begins to warm up the ground in May for most of the Lower Peninsula or in June for the Upper Peninsula.

One thing to look out for is early budding of semi-hardy plants when a late spring freeze can come along and kill off tender shoots which have started to grow. To be on the safe side, you can drape a sheet over the plant to carry it through a late spring frost. Be aware if you have slopes or valleys on your property. Since hot air rises, cold air can get trapped in these areas and create a frost pocket, especially in springtime, and destroy frost-sensitive plants which have set buds.

So next time you see a plant you simply must have, check it’s hardiness zone; if it’s a zone up from yours, think about any microclimates on your property that might just be the perfect spot for it.

Rita Henehan, a freelance writer from White Pigeon, is a member of Midwest Energy Cooperative. She is an advanced master gardener from Purdue University and is currently working on her first gardening book, “The Michigan Gardener’s Companion,” due out in December of 2007.