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questions about terracing a slope

Posted by hairmetal4ever Z7 MD (My Page) on
Wed, Jul 17, 13 at 13:38

If you have a slope, and terrace the slope, does it retain the microclimatological properties of the slope?

In other words...south-facing slopes (in the Northern Hemisphere) are more xeric, drier, hotter, than north facing. East and West of course more intermediate.

The simplest reason is that it modifies sun angle - if the sun at noon is 70 degrees above the horizon, a 30 degree south slope makes it the equivalent of directly overhead...while a north slope of the same angle would make the sun essentially be hitting ground at a 40 degree angle.

Plants on south-facing slopes leaf out earlier, have more heat/drought stress, and north-facing slopes tend to keep plants dormant longer, and temper the heat for plants that prefer more moist/coolish (relative to the area) environments.

North Slope - fruit trees, sugar maple, hemlock
South slope - cacti, upland Oaks, etc

If you terrace a large slope, you now have pieces of "flat" ground alternating with "vertical" ground. When it comes to planting, microclimate, etc, is it still a "slope" or is it more like flat land now??

If it's a south-facing terrace will it still dry out faster, leaf out earlier in spring, etc, than north facing, or does the terracing "level" the playing field (pun intended)?

Follow-Up Postings:

RE: questions about terracing a slope

Someone may have the information for one set of conditions, but there could potentially be many variables that come into play. So "best guesses" is probably the best you could hope for. In the end sum I doubt that there would be enough difference to warrant using plants that don't normally perform well in the zone in which the slope is located, though.

RE: questions about terracing a slope

its complicated. hmmm!! i read your post there is sloping and terrace problem thats why you couldnt design garden or anything according to your requirement. i would like to go with North Slope - fruit trees, sugar maple, hemlock

Here is a link that might be useful: greenandcleanlandscapes

RE: questions about terracing a slope

You have to take into account the number of hours of more direct sun light and if it is a slope even if terraced wouldn't there still be a high point blocking some of the northern terraced spaces vs. the southern which would see many more hours of sun.

The plants will still grow to reach for the sun. I notice this around my front porch where the back plants are leaning towards the front.

RE: questions about terracing a slope

From my observations in my own garden, which probably has more extreme conditions than your zone (-20 to 100 degrees over the course of a year and up to 120" of snow annually), the microclimate will be modified by terracing. The rain will be retained longer on the terraced slope making it more moist. There will be more surface area exposed to temperature fluctuations, so the soil will be hotter in summer and colder in winter. With a southern exposure, snow stays longer on flat terraces than on slopes here, both due to it freezing deeper, but also due to the different sun angle on a slope vs the alternating horizontal and vertical surfaces of a terrace. Snow melt flows away on a sloped surface while it tends to stay on a frozen flat surface and refreeze at night. For the most part, this probably doesn't make enough of a difference to plants to matter, but in cases of plants like western Agastaches which are borderline hardy for me and like it drier in winter than NH's typical conditions, it is the difference between survival most winters and no survival. I plant western Penstemons and Agastaches on slopes and they usually last several winters for me, since ones I've planted in terraced beds die over the winter.

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