Pushing the zone and water

I'm very interested in trying to push my zone from 8 to 9 since there are some very cool plants that become available at zone 9. But I'm also a bit concerned that if I use techniques to make warm micro-climates that I might also increase the water needs of my property. My thought is that a warmer micro-climate area is going to dry out faster resulting in an increase in water needs.

What do you all think would be the best ways to deal with that?

Off the top of my head I have thought that one way would be to use water features such as a reflecting pond to create a warm micro-climate to the north of it and also increase humidity plus groundwater availability which could offset any increase in water demands created by the warmer temperatures. I guess that might be part of it - if the techniques used to push the zone are the type that use water then you can avoid the issue of a warmer micro-climate needing more water.

If you use large rocks then the area under the rocks tend to stay moist and you can even cause water vapor in the air to condense out in the rock pile if it is large enough - called an air well.

But then there are methods such as raised beds that push the zone by keeping frost at bay (if set up correctly so the cold air flows around and off the beds) but are often drier than flat ground or a depression. Could you solve one problem but create another? Would simply mulching heavily address the issue of potential water loss?

I guess all in all I'm just unsure where the balance lies - I love the idea of pushing the zone but I don't want to increase the amount of water I need. Ultimately, I want to push the zone and reduce the amount of water I need. All in all I see using a combination of permaculture techniques to achieve this goal - but I could also see mistakes happening if I'm not careful.

What do you all think? I would love to hear from you all about this.

Mmmmmmm, zone 9.  I hear you.  I think there's a song in there..."I'm in zone 9 and i'm feeling fine!" "I'm in zone 8 and I'm merely great"

I have no experience here but from what I hear hugelbeds are just about always the solution. Certainly they are good at holding water, and make a slope that "puts" you many hundreds of miles to the south.  If you combine that with a sunscoop I am thinking that will warm your zone.  The pond idea too makes good sense.  And mulching, so long as you don't get to the point of building slug convention centers.

Are you on a roughly flat piece of land there?

I think it's also worth considering that the same total amount of sunlight/sun energy will be hitting your piece of land whether it's focused in one part or spread out, and so it will all be drying to some extent, as I understand it.  (I don't think the sunlight has to heat a specific atom to boiling point to turn water into vapor, because the air temperature never hits boiling but can someone speak to the physics of that?)  So if there's a change in water needs I think it would have more to do with the question of how much a given species of plant tends to transpire, right? are tropical plants more sweaty?

Then there's Willie Smits thing, that the sugar palms exude into the air some chemical that induces rain; I have also read from a more "woo-woo" source that all trees in general draw rain to them electromagnetically, if that's meaningful to you.  The point is, a tree that needs more rain (tropical) may invite more rain to it; but I think there would need to be a critical mass of them to make a weather pattern--but what I remember Willie Smits saying was that the exuded substance turned vapor into rain, it sounded like a fairly localized process.

Air wells sound good too, and Geoff Lawton uses trees' trunks themselves the same way (or nature uses them) as capturing a non-negligible quantity of dew (that's in Greening the Desert videos).

The last thing I can think of to consider is that there are really two different problems present here, and only one of them do you really need to address--moderating the temperature so it doesn't freeze your plants to death.  Zone is about low points, not averages.  You probably would do better if you can add more heat (up to a point) to the high points, but the more necessary factor is simply keeping them alive through the cold part of the year.  That can often be accomplished by a temporary mulch, a pile of manure, even a temporary hoop house or greenhouse.  You may not like these things, or they may cause slug problems if left there long (the mulch), but it wouldn't be as problematic in the cold part of the year and it would only be for a few weeks maybe, or a few months.

How's that for some armchair permaculture?

A little more on the point about the total energy being unchanged coming onto the land--if you make a sunscoop in one place, you shade what is behind that.  There will be more water relatively sticking around in the shady part there than on the sunny side.  Getting that water to spread back to where the sunnier plants are standing may require some finessing, but the plants in the hottest part of the sunscoop won't actually be that far away from the "zone 8" place.  So I'm thinking that the water will still spread over, as long as there is enough mulch or ground cover to prevent evaporation it's going to get where it's needed.

I learned that zone 8's are very different depending on where you are located. Im in 8a and started thinking about what i would need to do to be a zone 9. Cold is the biggest hurdle to overcome. We may get 3 overnight freezes a year, then one year it stays below freezing down to 17 degrees for 3 straight days.

While things like elevated beds may save the plants from a short overnight freeze, how do you deal with 72 hours below freezing? I suspect that trumps any heat gains you get with water tanks, rocks, holes, etc. It won't last as long as needed.

Im not trying to be negative. I guess my question is how to handle multi day freezes. It seems the most crucial aspect of the OPs goals. If there are any solutions besides covering plants and trees, i would love to here them.

Theres a movement here in texas for olive trees. Im not exact on my numbers but it generally goes like this: olives take 7 years to fruit. In 5 years a freeze comes that kills the upper tree. The tree comes back from the roots, the seven year wait starts over. In 4 years a freeze comes.........

wayne fajkus wrote:I learned that zone 8's are very different depending on where you are located. Im in 8a and started thinking about what i would need to do to be a zone 9. Cold is the biggest hurdle to overcome. We may get 3 overnight freezes a year, then one year it stays below freezing down to 17 degrees for 3 straight days.

While things like elevated beds may save the plants from a short overnight freeze, how do you deal with 72 hours below freezing? I suspect that trumps any heat gains you get with water tanks, rocks, holes, etc. It won't last as long as needed.

Im not trying to be negative. I guess my question is how to handle multi day freezes. It seems the most crucial aspect of the OPs goals. If there are any solutions besides covering plants and trees, i would love to here them.

Theres a movement here in texas for olive trees. Im not exact on my numbers but it generally goes like this: olives take 7 years to fruit. In 5 years a freeze comes that kills the upper tree. The tree comes back from the roots, the seven year wait starts over. In 4 years a freeze comes.........

Good point.  What does Sepp do?  

Annualized thermal inertial...I still don't get how that works yet quite, but for the basic idea of "soil takes a long time to heat up or to cool down".  Even more than rock?  

A little composting poop and sawdust could help...not the most elegant solution.

Is there a thread started for the olive trees? that seems worth discussing.

I think the idea of a sunscoop type of hugel mound that has a small pond at the base of it would be the most effective way to address the specific concern in the OP. You have a sheltered, raised, sun facing slope that sits over a mass of water holding material with a source of atmospheric humidity right at it's base.

To the physics of evaporation, I think that the theory is that a single photon does strike a single water molecule and that causes that specific molecule to elevate in energy enough to change phase from a liquid to a gas (or maybe just breaks a bond with other water molecules that allows it to become light enough to be less dense than the air?). In any case it is about stopping photons from hitting h2o molecules, this is why mulch works, this is why shade works (as said above, the backside of your sunscoop hugel with be shaded and remain much moister as a result), this is why there is evaporation without ambient boiling temperatures.

More broadly though I think wayne is on the right path, it's more specific than just 'pushing zones', it's really a question of what changes you are trying to draw into a specific place. You may want to extend the time that a temperature range is present, you may want to raise the daytime temp or the nighttime temp, you may want to dry the soil or keep it more moist, you may want to reduce wind, avoid frost, delay frost, etc.. This isn't just a question of your location, it's also a question of what specific plants you want. I'd imagine that there are lots of zone 9 plants that like drier conditions. Lots of variables.

But specifically for the issue of raising the minimum average temperature with minimal reduction of the average soil moisture/humidity, I'm going with sun scoop hugel around a pond. Sepp promotes a style called a kratergarten (crater garden) to create topography on a flat, urban lot, so a bit of exploring in that realm might lead to some inspiration.

If you push the zone...and grow the.new zone plants
Won't the new zone plants be more drought hearty and naturally prepared for rapid dry-out if any occurs? And be less water needy...just asking

There are quite a few methods that won't necessarily require adding in more water. Growing tightly against walls, using the edge of tree canopy, growing among large rocks, using slopes - those methods can net you an extra growing zone. I was surprised to see pineapples thriving around the trunk of an oak tree at the edge of USDA zone 8. They can't take frost - and they're supposed to grow in full sun - and yet, there they were. The trunks of the trees act like space heaters.

My default solution to these types of questions is to change the genetics of the plants that I am growing... USDA zones reflect the coldest temperature that can be expected during a winter. That affects how likely a particular plant is to freeze to death. There is natural variation within a species to cold tolerance, so my solution is to plant a lot of genetically diverse seeds from a species and let the weather screen them for what is winter hardy in my climate. I don't have to change my climate, all I have to do is change the genetics of the plants that I'm growing.

We have had great success moving species from warmer climates.  I'm growing tomatoes that smirk at a snow-storm, and beans that tolerate frost when other varieties croak. I'm growing hazel, pistachio, walnut, and peach that migrated in from warmer climates. Sure the walnut breeding project has been ongoing since before I was born, but whatever.

Testing tomatoes for frost tolerance


Mostly dead with a few survivors is a wonderful result.


Tomato variety that smirks at snow.