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Thursday, January 13, 2011

Look for Microclimates in the Garden

You have a world of climate and weather variety all around you. Temperatures are warmer the farther south you go (reverse that in the Southern Hemisphere). Mountains are colder than an ocean beach. Tree tops are windier than valleys. The coasts are rainier than deserts. This is easy to recognize on a broad scale, but have you noticed differences within your own garden and yard?

Snow melts around my raised pots first.
First, a couple of definitions. Weather is what's happening outside today. It's cold or hot, rainy or sunny, windy or calm. Climate is the weather pattern over a longer period of time. Climate is affected by where you are on the earth (your latitude), your elevation, local topography, and proximity to large bodies of water. My climate is semi-arid and today my weather is sunny and dry.

Within my yard I have a number of topographic and man-made features that alter weather patterns just as larger features on the planet do. My house blocks the prevailing winds. Trees and fences project shade on a sunny day. Stone patios and concretes sidewalks warm the ground. These differences, and more, create microclimates all over my yard.

This bed gets warmth from the house, is protected from the prevailing wind, and receives morning and early afternoon sun.

Microclimates are areas with a different climate than larger, surrounding areas. Microclimates can be quite big, like the area to the east of the Great Lakes that receives completely different winter weather than nearby regions, because of the large bodies of water. Microclimates can also be quite small, like the shaded spot behind a low fence; only a few feet can make a difference.

Whether you know it or not, much of your gardening success happens because you are aware of the microclimates in your garden. You know the spots where some plants do better than others. You know not to plant Hostas on a sunbaked hill; they need the shade on the north side of your house. You know to plant small, tender transplants where they're protected from strong winds. You know that tomatoes do better in a raised bed than in the low gully behind the barn.

Now is a great time to identify some of the different microclimates in your garden and yard. Recently, weather has been cold and snowy in the U.S. and right now 49 of the 50 states have snow on the ground. Snow provides wonderful indicators for microclimates. The spots that melt first are warmer; the spots that melt last are colder. Spots with little snow may show windy areas as it all blew away; spots with more snow due to drifts are typically not as windy because that's where the snow came to rest.

This south-facing wall melted snow during 48 hours of below-freezing temps.

Look for differences in the landscape. If you have snow, look for the clues. If you don't, you can still determine microclimates. Do you have leaves piled up behind a fence? That area is more protected from the wind. Do you have ice in some spots and not others? That may be due to shade or because that spot is lower, and cooler, than nearby areas. Is the grass already green in some areas and not others? That may be due to more water for the green areas and drier conditions in others. Is the grass starting to grow near sidewalks and patios? That may be due to warmer temperatures provided by the concrete.

Remembering a little about physics helps too. Dark colors absorb more heat than light colors. Light colors reflect more sun than dark. Hot air rises, cold air sinks. Light-colored, south-facing walls will reflect sunlight. Dark soil will warm faster. The top of a hill is warmer than the base in the valley, even if the hill is just a few feet high. Low areas will have frost before higher ones.

The USDA Plant Hardiness Zones provide a general guideline of climates (sustained low temperatures) for plants. Within your garden you probably have localized Hardiness Zones that are colder than and also warmer than the published Zone for your area. By identifying and recognizing the small differences in your garden you can put plants into the best location. Hardy plants may be able to handle a colder spot while tender plants may need the boost from a warmer location.

You can also create aspects of your garden to develop microclimates. Raised beds thaw out faster in the spring, allowing you to plant earlier than other beds. A fence for tall flowers or berries will protect them from the wind. Planting corn or sunflowers can provide a shady spot behind them for tender herbs. Planting trees for wind and sun protection changes the microclimates all around. A concrete or brick walkway or patio will warm the soil nearby.

This stone patio provides a little extra warmth to the new lavender plants around it.
Once you recognize the existence of microclimates in your garden, success may no longer be a mystery. If you planted 10 bushes and the two on one end were smaller or died, look for a microclimate as the culprit; maybe they were in shade, or drier, or exposed to wind. When the tomatoes do better in one bed than another, maybe it's due to more sun, or less water, or warmer soil.

Be on the lookout constantly for microclimates and use them to your advantage. Just as the snow makes it easy to identify some, bright sun and shadows give clues too. Make note of where they are and plant accordingly. You may be amazed at the results.
You have a world of climate and weather variety all around you. Temperatures are warmer the farther south you go (reverse that in the Southern Hemisphere). Mountains are colder than an ocean beach. Tree tops are windier than valleys. The coasts are rainier than deserts. This is easy to recognize on a broad scale, but have you noticed differences within your own garden and yard?

Snow melts around my raised pots first.
First, a couple of definitions. Weather is what's happening outside today. It's cold or hot, rainy or sunny, windy or calm. Climate is the weather pattern over a longer period of time. Climate is affected by where you are on the earth (your latitude), your elevation, local topography, and proximity to large bodies of water. My climate is semi-arid and today my weather is sunny and dry.

Within my yard I have a number of topographic and man-made features that alter weather patterns just as larger features on the planet do. My house blocks the prevailing winds. Trees and fences project shade on a sunny day. Stone patios and concretes sidewalks warm the ground. These differences, and more, create microclimates all over my yard.

This bed gets warmth from the house, is protected from the prevailing wind, and receives morning and early afternoon sun.

Microclimates are areas with a different climate than larger, surrounding areas. Microclimates can be quite big, like the area to the east of the Great Lakes that receives completely different winter weather than nearby regions, because of the large bodies of water. Microclimates can also be quite small, like the shaded spot behind a low fence; only a few feet can make a difference.

Whether you know it or not, much of your gardening success happens because you are aware of the microclimates in your garden. You know the spots where some plants do better than others. You know not to plant Hostas on a sunbaked hill; they need the shade on the north side of your house. You know to plant small, tender transplants where they're protected from strong winds. You know that tomatoes do better in a raised bed than in the low gully behind the barn.

Now is a great time to identify some of the different microclimates in your garden and yard. Recently, weather has been cold and snowy in the U.S. and right now 49 of the 50 states have snow on the ground. Snow provides wonderful indicators for microclimates. The spots that melt first are warmer; the spots that melt last are colder. Spots with little snow may show windy areas as it all blew away; spots with more snow due to drifts are typically not as windy because that's where the snow came to rest.

This south-facing wall melted snow during 48 hours of below-freezing temps.

Look for differences in the landscape. If you have snow, look for the clues. If you don't, you can still determine microclimates. Do you have leaves piled up behind a fence? That area is more protected from the wind. Do you have ice in some spots and not others? That may be due to shade or because that spot is lower, and cooler, than nearby areas. Is the grass already green in some areas and not others? That may be due to more water for the green areas and drier conditions in others. Is the grass starting to grow near sidewalks and patios? That may be due to warmer temperatures provided by the concrete.

Remembering a little about physics helps too. Dark colors absorb more heat than light colors. Light colors reflect more sun than dark. Hot air rises, cold air sinks. Light-colored, south-facing walls will reflect sunlight. Dark soil will warm faster. The top of a hill is warmer than the base in the valley, even if the hill is just a few feet high. Low areas will have frost before higher ones.

The USDA Plant Hardiness Zones provide a general guideline of climates (sustained low temperatures) for plants. Within your garden you probably have localized Hardiness Zones that are colder than and also warmer than the published Zone for your area. By identifying and recognizing the small differences in your garden you can put plants into the best location. Hardy plants may be able to handle a colder spot while tender plants may need the boost from a warmer location.

You can also create aspects of your garden to develop microclimates. Raised beds thaw out faster in the spring, allowing you to plant earlier than other beds. A fence for tall flowers or berries will protect them from the wind. Planting corn or sunflowers can provide a shady spot behind them for tender herbs. Planting trees for wind and sun protection changes the microclimates all around. A concrete or brick walkway or patio will warm the soil nearby.

This stone patio provides a little extra warmth to the new lavender plants around it.
Once you recognize the existence of microclimates in your garden, success may no longer be a mystery. If you planted 10 bushes and the two on one end were smaller or died, look for a microclimate as the culprit; maybe they were in shade, or drier, or exposed to wind. When the tomatoes do better in one bed than another, maybe it's due to more sun, or less water, or warmer soil.

Be on the lookout constantly for microclimates and use them to your advantage. Just as the snow makes it easy to identify some, bright sun and shadows give clues too. Make note of where they are and plant accordingly. You may be amazed at the results.

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