permaculture

[George Anna Clark <esac@laneta.apc.org>]

Almost forgot to report...

I met some campesinos in the state of Tlaxcala, Mexico who swear by 
water-filled glass bottles, placed in the paths between the vegetable 
beds. I assume their temperatures dip only a few degrees below 0....

good luck,
george anna
south-central Mexico

jedd wrote:

> On Fri, 5 Oct 2007, Richard Archer wrote:
>  
>
> > I'm developing a site that tends to be frosty through winter and
> > into mid-spring. Overnight low temps get down to -6 C. Daytime
> > maximums in Winter range from about 4 C to 14 C.
> >    
>
> I get down to -4, maybe -5 - but in winter at least get higher
> temps - usually up around 20C.  (Where are you, btw?  I'm around
> the top end of the hunter.nsw.au)
>
> Warmer day time temperatures make it easier to use a pebble/stone
> mulch for its thermal inertia.  Another frost-protection method you
> didn't mention is covering the young plant (once it gets to a certain
> height its new growth is typically better protected) with a tripod of
> timber and growing winter vines over the thing.
>
> Or even using an artificial covering -- I usually bubble wrap my
> passionfruit, for example, from May through September.  This is
> easy to do as its growing on a trellis, so the framework to attach to
> is easy.  For standalone plants you need something special - 4x steel
> posts with 2" polypipe loops over the plant and shadecloth over the
> top, for example.  The same structure is reusable in subsequent
> years, or alternate for summer protection of other plants.
>
>  
>
> > - Sun traps - a parabolic planting facing sunwards and to hopefully
> > retain sufficient heat from the day to prevent frost at night.
> > Can also use water to reflect more heat into an area.
> >    
>
> You definitely need something to accumulate and release the heat
> with this approach, and rocks are typically the best option.  You
> may need a backup plan in the event of several days of 4C max, as
> you just won't get the necessary heat input to keep you going
> through the nights.
>
>  
>
> > And in a non-permaculture approach... has anyone had experience
> > with overhead sprinklers automatically triggered with a frost
> > sensor?
> >    
>
> I haven't tried this, as I don't have sufficient water pressure (I'm
> on gravity feed only) to do sprinklers, and I'd be worried that all
> my plants would die in one night if the power or sensor went out.
>
> I can recommend getting a couple of temperature dataloggers that
> you can put about the property.  These will log temperatures at
> various intervals (mine are usually set to 5 or 30 minute) and run for
> months at a time, then get plugged into a USB port on your poota,
> with the data coming in as a CSV.  They're accurate up to 0.5C,
> but are particularly useful for working out temperature differences
> between two or more sites.  These are definitely planning devices,
> rather than reactive / triggering devices.  The only ones I know of
> are from Jaycar and cost about $120 each.
>
> In the Designers' Manual, Bill talks of frost amelioration by digging
> holes.  I never quite got how this worked, and have been meaning
> to try it out - or better yet find someone who's done it and can
> comment on its efficiency.  Page 120 / Figure 5.13 for those with
> the tome at hand.
>
> Jedd.
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