I haven’t given much thought to using South facing walls for growing, because my property is mostly a North-facing slope with the house planted on the Southwest corner 100+ foot fir trees uphill to the South.
We’re thinking about getting a relatively inexpensive steel building, and still trying to figure out where to put it where it won’t be in the way and not too enormous a task to level the ground. It raises the possibility of some space to the South of it. But would its thin steel walls be any benefit? I imagine it will reflect some light, but not be a significant heat reservoir.
South facing wall usually implies the wall of an insulated building. If said building is on a slab or basement foundation there is a lot of heat that gets dissipated into the soil. The wall itself both radiates heat and is warmer than a free standing wall.
Just a wall from a non heated building will work but not all that great; a cloudy day or two and the benefit will be negated. If you were counting on it to keep a borderline plant alive it may not work.
I have a very tall red brick direct south facing wall on my house and the ground there slopes down hill to the south too… which makes it ideal. That is where I choose to plant my fig tree and I have my new greens bed there too.
If we get a snow… it is the first place in my yard that the snow melts.
I ran across this vid on youtube the other day… just a very nice small cabin like structure in the woods… with metal siding… but at the base of the walls, they dressed it up with some stonework. Looks really nice.
Not sure if something like that would work for your situation… but I think it looks really good (the mix of baton/board like siding and stone) and I am sure a sunny bed on the south side of stonework like that would catch the heat.
How large is your property? Do you own and control the hillside on south side? Is the hillside and trees protecting you from prevailing winds? Finally what types of plants are you desiring to grow? Trees or more garden type low growing plants?
2.5 acres. My house is in the Southwest corner of what I own, so no, I don’t own the Hillside above me to the South. I’m mostly interested in growing fruit trees that can be harvested above deer browse. If we had better fencing, that might change a little.
My understanding is that northern growers of apples and peaches prefer north-facing slopes. The reason is that south-facing slopes tend to encourage early emergence from dormancy, leading to flowering that is vulnerable to late frosts. I remember reading very pointed warnings that the worst thing a northern grower can do to an apricot tree is to plant it against a south-facing wall.
The more you are zone-pushing (i.e., the more cold-sensitive the tree), the greater the apparent risk that a south-facing slope will cause similar problems for whatever species you are growing.
When I lived in Vancouver, I remember some homes on the west hills of Portland used relatively high sun shades that were erected on the west side of their decks to provide a shaded canopy for the summer, the shade panels were set at an angle roughly equal to the latitude so that the majority of direct sunlight was preempted, while indirect lighting was still allowed. You could consider this concept but use lexan panels instead to allow and amplify the sunlight for growing. Inside such a grow shelter you could use either dark red pavers or weed block to create a heat absorbing atmosphere. Then maybe use either a tall or electric fence around this smaller structure to keep the deer at bay. Some sort of enclosed patio design might actually add value to the home while using the house walls to help enclose it. The structure need not be fully enclosed but enough to block prevailing winds that would detract from heat absorption. Instead of lawn use darker landscape rock or pavers. Two years ago I constructed a covered canopy over an arbor where I was testing if I could grow Muscadines which require a long hot growing season. Used just white quilted growing fabric as a cover. Underneath the canopy each day I measured the change in temperature anywhere from 7-15 degrees higher than ambient. The vines looked much better in response, but the experiment failed as they still did not ever flower, so I learned there are some things you cannot compensate for, even in a microclimate. But I was surprised at how effective just a 6’ wide, 50’ long canopy could be to promote growth. My biggest challenge was the wind. Much of this is Just throwing out some concepts that may not be worth considering Jafar, but may get you thinking in the right direction! Good luck and keep innovating