Climates and Microclimates, What’s the Big Deal?

  • Difficulty Rating: Beginner
Climates and Microclimates, what’s the big deal?

You probably know all about the USDA Plant Hardiness Zone Map, but do you know what it means for your garden?

Although this zone map highlights the cold hardiness for a particular region, your entire climate—both hot and cold, along with humidity and sun intensity—determines how well a particular plant will perform in your garden. For example, Raleigh, North Carolina is in Zone 7, as am I. However, because of humidity and other factors, they can grow Japanese maples in the sun. In Oklahoma, if you planted most of these small trees in the sun, you’d be setting yourself up for a crispy disaster. I live in a prairie climate while Raleigh’s climate is much more moderate. Plus, they have more rainfall at approximately 45 inches per year. Oklahoma, on the other hand, gets an average of 36 inches. Nine inches of rain makes all the difference.

USDA-Zone-map

To stretch your growing horizons, use microclimates to your best advantage. This works for both heat and cold hardiness.

What is a microclimate? It’s a protected area within your landscape that is generally moderate and warmer than the rest of your garden. So, if you live in Zone 7a like I do, you may be able to stretch your zone to 7b or even 8a by using a microclimate within your yard. This also works for intense heat. If you have an area that gets more shade in the afternoon, you are using a microclimate to protect delicate plants from too much sun. Since I adore Japanese maples, I grow them in partial shade, usually on the east side of my house.

Gardeners seem to always want to grow plants not suited to their area or zone. Maybe it’s our competitive nature. My husband says gardeners are the most competitive group he’s ever seen, and this always makes me smile. I know I frequently use microclimates throughout my garden when I want to try something new. I save my ornamental grasses and tough prairie natives for the harsher places in my landscape.

Ornamental grasses and tough prairie natives

The bed, above, is on the east side of my garage. I discovered the east side of my house is where I need to grow less hardy plants. The soil is builder’s sand left over from construction. To this, I added compost, mulch and manure to create one of the most fertile and well-draining borders in my garden. I grow three David Austin roses in this border, ‘Darcey Bussell’, ‘Molineaux’ and ‘The Alnwick Rose’ along with two different Japanese maples and two Chamaecyparis obtusa (false cypress) that would otherwise expire from heat exhaustion. Here is the same border in early spring. Not much to look at right now, but in a month or two, it will be a riot of color, texture and form.

Garage-garden-with-Fiskars kangaroo bag and rake

Oklahoma is plagued with late freezes that ravage our fruit trees. When I decided to plant my own fruit trees, I placed them in my front yard because it is protected by a stand of native oaks, and is on the highest part of my landscape. My home is built on a hill. I knew if I planted the fruit trees in the lower garden, I would never get a peach, tart cherry or apple crop. I still fight the late freezes each year, but at least I give these trees a chance to do their thing.

Dee's lower garden at her home

Contrast these two microclimates with the lower garden extending from the back of my house and down the hill. The bottom of the garden is the coldest region in my entire landscape. I only plant beautiful natives and other tough shrubs, perennials and grasses in this space. I only have one Japanese maple here, and it is in the uppermost portion of the garden in partial shade. Even so, after last winter with its extreme cold, I may lose this tree. That’s the thing about gardening that is most challenging and frustrating…you can do everything right and still lose plants. It’s just part of the game.

Next time, when you’re thinking about buying a plant at your local nursery, don’t just consider its soil, sun or shade requirements. Take into account those areas of your garden where it would be most happy due to a microclimate. You’ll find that if you work these sheltered areas to your advantage, you’ll have a much happier and more productive garden.