A North Facing Slope, and raised beds

[matt walker]

So, I mentioned this in my swale thread, but I wanted to go a little deeper into it. I'm just thrilled at this realization, although I know it's nothing new. It just took me a little longer to get it. :)

In Eliot Coleman's "Four-Season Harvest" he states, "Along the 44th parallel, a garden on soil sloping 5* to the south has the same solar climate as flat land 300 miles further south."

To someone who has all North facing land, and has felt a bit discouraged by this over the years, this is a HUGE revelation. And it got me thinking, how big of a hill do you need before you have a south facing slope? I pondered this because I used to always think "if only I was on the other side of this hill." As if 1000' to the south was going to have a different climate. I realized that it's not the size of the slope at all. I'm just very, very excited to combine this knowledge with my current raised bed gardening technique, as well as hugelkulture mounds and swales.

My thinking is, if I can create large mounded Hugels, swales, and beds, I can plant on the south slope and get a micro climate that changes my growing environment completely. I'm kinda freaking out over this, as it could be a total game changer in my cold, ocean view hill side, north facing slope. I've constantly struggled with trying to warm things here, even in summer. It's rarely over 70*, so if I could warm up the growing areas by even a small bit this will change things for me immensely.

Does anyone have any first hand experience with this? I'd love to hear your thoughts.

[pa_friendly_guy]

Sorry Matt, I have no experience with this idea. My thoughts are that to have a " South Facing Bed " it would have to be high enough to see the sun from ground level. The more hours of the day that you can see the sun from that ground level the better.

[matt walker]

The premise of my epiphany is more about the angle the sun strikes the soil's surface, rather than just time of exposure. As an example, think of solar panels. They always are installed to try to present the panel at a perpendicular angle to the sun's rays. People will install complex tracking systems to keep them just so, as their efficiency drops off rapidly as the angle of attack deviates from perpendicular.

I am of the mind that the soil's surface operates exactly the same way. I have noticed that when I hike "my mountain", aka the hill behind my house, as soon as I crest and am on the south facing slope, the solar warming is significantly greater. And further, I don't think the slope needs to be 2000 vertical feet to achieve this difference. I am of the mind that a berm which has 2 vertical feet of south facing slope will offer a similar solar climate, at least to little tiny plant beings.

Basically, I'm postulating that although I have a north facing slope as my site, I can mimic the solar climate of the other side of the hill by planting on sloped "solar collecting" beds, mounds, or swales.

Now, I don't know if that's entirely accurate, but the quote I found in Coleman's book above seems to indicate it is. If 5 degrees offers the climate of a location 300 miles south, what are the gains to be had when currently my site faces north at 7 degrees, and I can plant on a slope that faces south at 14 degrees?

I'm excited, and I'll keep working on this. One part of the epiphany was that I get this slope as a byproduct of hugelkultur, swales, and purposely designed raised beds.

[eeldip]

i think there are three things going on... there is the solar energy collected by a flat object on flat ground vs. angled ground. this would impact the radiation heating of the soil. this won't affect a growing plant so much, or perhaps not at all, because they will grow towards the sun/angle their leaves to adjust to such a small change in slope.

the other warming effect from a south facing slope is the buildup of warm air that creates some convection warming. so, you get free heat from land below you.

and then you have the effect that mr. friendly talked about, a south facing slope has longer daylight.

basically re-angling your beds will get you a little bit of 1, but nothing extra from 2 or 3. if my physics holds up...

[matt walker]

Yeah, I think that's basically true, BUT, in my zone getting the soil warm is a big deal. And, I think it could make a big difference in the ambient temperature a few inches above the surface. I mean, if I stand on the south side of a 2' mound, I'm probably not going to be any warmer. But if I was a 2" tall seedling, trying to start in the cold of spring, I would think that I would be much warmer on that small slope than I would on the same spot angled even slightly north.

I dunno, it might not make that much of a difference, but I just read the chapter again in "Four-Season Harvest." He's describing planting styles in France where they shape whole fields like that, with the sloped beds having the French name ados or cotieres. See, if there's French words, it's gotta be good!

[eeldip]

well, if you busted out some serious earth moving machines, and made a series of south tilted tiers, i bet you could make an impact. but i would wonder how much impact you would get for all that effort.... probably way less that just growing in tunnels in the hump season.

[matt walker]

Yeah, tunnels, check.

I'm thinking I'm going to tilt the beds outside as I add material to them, I mean, I can't see it hurting. But also yeah, I'm not thinking of trying to convert all my land to tilting the other way. Just, you know, a little here and there for stuff that needs a little extra warmth.

[Lollykoko]

[matt walker]

Yes, at least, I'm going to try building a hugel bed this year, and see how it goes. I'll be honest, I'm a bit skeptical that the hugel is the best method for my area. The soils are all old forest bed and typically full of organic matter and wet. That said, I'm going to give a try for sure, I have tons of material here to experiment with.

I also am excited to just incorporate that concept of small south slopes into my regular garden beds. As I work them in the spring, I'm going to start subtly shaping them to slope towards the south. I realized that on my north sloping site, this will not only (hopefully) provide a warmer, more sheltered spot for seedlings, but then any surface moisture will run down that slope into the uphill trough and hopefully add more water to the area under the bed.

[Lollykoko]

I also have soil that is rich with organics and a high water table. No running water on site yet, except in the drainage ditch 10+ feet lower than the surrounding ground, so irrigation is NOT part of my future plans. I will be counting on the hugelbeets to store / draw enough moisture from the surrounding ground to take care of all but the most thirsty plant forms.