I am in zone 10a though it is known to get to 28 degrees where I'm at most years. I have planted a breadfruit tree which I know will be rather unhappy come winter time. While I plan to cover it and use Christmas lights during frosts, I'd like to work towards creating a micro climate for it.
My thought is to stack a lot of rocks around it. But I'm very much open to other ideas as well. Issues and notes:
1. I am on sand and don't have many rocks at my disposal. I consider them very valuable commodities so don't want to use more than I need to.
2. During frosts, I am told by old timers that the cold air/wind comes from the Northeast every time.
The picture below shows the breadfruit, my mulch ring (it is surrounded by grasses otherwise), a few rocks for lizard habitat I placed, and north, south, east and west. Questions:
A. How much rocking do I need for a decent micro climate?
B. How close to the tree should I put it?
C. If the cold wind comes from the northeast, which area around the tree should I put the most rocks?
D. Suggestions other than rocks?
The video I recall seeing of Sepp Holzer's microclimates show really quite enormous piles of huge boulders, I think it is the "Terraces" video....References say Breadfruit is "ultra-tropical" and prefers temperatures between 60F and 100F....
hugelkultur's designed correctly can aid in microclimate creation quite a lot by keeping the wind off of the lower part of the tree and the ground, east to west running beds capture sun all day and having some at the end of east-west running beds will help to shed cool winds rather than creating an area that allows cool wind to tunnel and penetrate more...
rocks and bodies of water also help
with all these, the BIGGER the better and more stable:)
barrels of water painted black or covered with soot could work, too. not particularly aesthetically appealing.
a concrete wall would act as an artificial rock. that wouldn't be particularly ecologically appealing. chances are good you could find some concrete rubble to stack up, though, in which case you would be in the karmic clear. blackening with charcoal or soot would increase the effect.
building your outdoor kitchen with rocket mass heater and bench on the northeast side of the breadfruit could work. that's a bit extreme if you don't already have one of those planned.
I certainly sympathize with wanting to grow plants that are marginal for your climate zone, but there may well be some compromises involved if you want it to succeed.
Love this question...I've been thinking the same thing myself - with a baobad tree........
I have a lot of rocks available, and am hoping to make a horseshoe type hugelcultur with a lot of rocks too.........Or a wattle fence using willows cut from the creek....
Where are you located?? Wish I could give you some rocks....My son digs them up for fun......... [kindda compulsive about it..........]