Microclimates in the Garden

Microclimates give gardeners an opportunity to grow plants that might not normally be successful in their landscape. Microclimates can also spell doom for plants that should grow well. As in the real estate game, in gardening it’s all about location, location, location.

Some spots show obviously different reactions to weather

A microclimate is a geographical area with a different climate than the larger area surrounding it. The effect of localized weather varies in microclimates. Some microclimates cover miles of territory, but for our garden discussion we’re talking about garden spots that may only be a few feet wide. Every season offers the opportunity to find microclimates in your garden (see my articles: “Look for Microclimates in the Garden“, Jan 13, 2011; and “Microclimates in Summer“, July 8, 2011). Spring is a good time to try and identify some of the microclimates in your garden that you may not notice at other times.

Gardening is a long-term activity and by noting changes in your garden throughout the year you can use your time and effort to provide the best environment for your plants. Microclimates exist everywhere but until you notice their effects on you and your plants you may be wasting valuable resources.

Some microclimates are obvious. Maybe there’s a spot in your yard that is always high and dry; snow melts first in that spot, grass dries out and needs more water in that spot, or maybe every shrub you plant dies in that spot. Pausing for a little analysis may reveal it is always sunny, windy, and exposed. That’s a microclimate.

On the other end of the spectrum think about the garden bed that is always wet and cold. Maybe its a low spot under some trees that never sees sun and never dries out; maybe it’s the spot that always has the last pile of snow in spring. That’s a microclimate.

These two microclimates may exist mere feet from each other but to plants they may as well be separated by miles. A plant that can grow in one of them can’t grow in the other. It’s up to you the gardener to recognize the differences and act accordingly.

My wife and I have noticed an interesting microclimate in our yard. We have three stands of Aspens that are each only separated by about 50 or 60 feet (15-18 meters). The stand in the front yard always buds out first. Two or three weeks later as those trees have full leaves, the second stand begins to show signs of green. Another two or three weeks go by before the third stand finally begins to leaf out.

Trees on right have leaves, new growth in the middle, no leaves on the left

An analysis of the landscape reveals a minor grade in the landscape; the last Aspen stand to grow is in the lowest elevation. The upper stand also gets a little more sunshine; the lower stand is shaded by trees and the house late in the day. It’s also likely that the lower stand is more exposed to wind, common in the spring; the two upper stands have some wind protection from nearby structures and other trees.

No leaves and noticeable terrain difference on the left

Recognizing this microclimate is important to my gardening and plant selection. And I’ve made mistakes by not analyzing it earlier. Initially I planted Irises under the trees in the lower stand. They get full sun in early spring before the trees leaf out and I thought that would be enough for their success. The problem comes in autumn. As you might guess, the upper Aspen stands drop their leaves first and this lower stand is the last to lose leaves in fall. That means that the Irises are still shaded when they should be getting sun to nourish their rhizomes. I never get the flowers I should because the Iris rhizomes aren’t nourished by sunlight as well as they should be.

This microclimate analysis changed my approach to plant selection. First, I planted new lavender plants near the upper Aspen stand. The slightly improved sun exposure helped those lavender plants grow better than others in the back yard. This year I’ve planted Coral Bells (Heuchera) in that lower spot. Coral Bells like sun when it’s cold and some shade when it’s hot, exactly what the location offers.

Without a microclimate analysis I might spend years fertilizing and babying the Irises and other plants that were never really suited for that garden bed. Now I can focus on the proper plants for better success.

Another microclimate, that I created, is evident in my stone patio. I wanted a spot to support the growing requirements of lavender and other high desert plants. I chose a location that gets full sun and build a raised, stone patio. It is now the spot that warms quickly in spring and where snow melts first. The lavender, sedum, thyme, and iceplants are thriving in a spot designed for them.

Warm stone helps surrounding plants

I chose a nice location with full sun for my vegetable garden. But even in this select area microclimates exist. The raised beds are built on a slope and the upper beds are a few feet higher in elevation than the lower. The upper beds have more exposure to wind and receive late-day shade before the others. Last year tomato plants in the lower beds did better than tomato plants just a few feet away; the wind and shade made a difference even though it is barely noticeable to me. The plants obviously noticed.

Look at how your garden wakes up in spring. Note the different growth rates of plants just a few feet apart. Spot elevation, sun, and wind variations in your landscape. Take a few minutes to analyze why some plants do well while others struggle.

By thinking about microclimates in your garden and acting to match plants with the best growing environment you can improve your garden’s success. We often don’t think much about a minor difference in temperature, sun, or shade, but to tender plants it can mean the difference between life and death.

Before you put new plants in a garden bed and before you sow seeds notice the year-round characteristics of that spot of ground. It may be perfect for young plants in the spring but does it offer the best environment and microclimate later in the plant’s life cycle? The best gardening practices look into the future. It may sound difficult but it begins by thinking about how little differences in localized climate exists from one section of your garden to another. By spotting these changes you can use microclimates to your advantage.

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2 responses to this post.

  1. Posted by attemptinggreen on May 7, 2012 at 2:05 pm

    This was an excellent post. I have been noticing lots of microclimates at my house this spring. Especially 4 azaleas that line the path to my front door (they were planted there by the previous owner) all are planted about 18 inches apart however, 3 receive 6-8 hours of sun while the one closest to the house gets only about 3 hours sun because the house shades it. 3 in full sun are in full bloom right now and the one in the shade is barely flowering.

    Reply

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