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How to manage microclimates in winter gardens

Days of pouring rain, high winds, frost or knee-deep snow are terrible times for gardening. But you can learn a lot by watching the routes water takes or noticing where freezing lasts longest.

Days of pouring rain, high winds, frost or knee-deep snow are terrible times for gardening. But you can learn a lot by watching the routes water takes or noticing where freezing lasts longest.
Even small space gardeners benefit by checking wall-side pots that were so successful in summer for tomatoes and peppers. Perhaps they’re right under a roof overhang – and winter veggies or spring bulbs are being half-watered or not watered at all.
Sometimes there are places where drips target one particular spot. In heavy rains, slow-draining clay soil turns low spots into ponds. Meanwhile, sandy soil erodes so that roots are exposed to the next freeze. Raised beds are a blessing to clay soil gardeners, especially on level lots that can’t export water downhill. Excess rain that drains from these beds can collect on paths instead of saturating the soil. Cold air also flows down onto these paths.
Sometimes water really benefits a garden because bodies of water are heat sinks just like south walls are. This ability is why places near lakes and oceans have a more mellow climate than areas further inland.
Ponds in gardens – even small container ponds – draw in heat during the day and radiate it out at night. It may not seem significant, but even a little warmth can make a difference whether a semi-tender plant survives the winter or not.
Large rocks and paving are also heat sinks. The plant that gets its roots under paving may lose its top growth to frost, but the roots can take much more cold because the paving acts like an insulated blanket – at least as good as mulch and much less work to maintain.
But the best heat source of all is a house wall. The bonus here is that there’s usually a small amount of heat radiating from the house itself.
South walls are usually the warmest of all because they tend to get more sun. This allows heat from the sun to get drawn into the wall and later released.
Most gardens have a direction that needs shielding against cold winds. Sometimes, people build solid fences in the direction these winds come from, but this isn’t a good idea. Winds tend to impact solid fences, rise over them and slam down on the other side in unpredictable ways. Very high winds can topple solid fences.
Not-quite solid fences do a better job of filtering the wind. Fences with small slats or other spaces within their design are also a good solution for hillside gardens where cold air moves downhill and creates a frost pocket whenever it hits a solid fence. But evergreen trees or hedges do the best job of all in shielding against winds. Cedars are one popular solution. Excelsa is a relative of our native Western red cedar. The popular Smaragd belongs to the Eastern white cedar group.
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