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Re: Mist Bed Questions

skid@bway.net wrote:
> 
> Dear Group,
> We want to set up a mist sytem for an outdoor (summer) prop bed, and our
> questions are as follows:
> 
> Using a regular house type (water) water source, what kind of timers for
> the misting are out there? The only ones we have been able to find have
> been priced at well over $100.00....any recommendations?
> 
> Also, how often, and what duration should the mist cylces be?  Should the
> mist be less during the night?
> 
> Finally, we have seen a device that turned the misting on & off by wetting
> and then drying action, does anyone know what that is called and where to
> get one, price etc.
> 
> TIA,
> Bill & Harvey
> SKID Plants  Zone 6  CT  USA

Hey Guys.  The implementation of the misting system in propagation is
the greatest thing since sliced bread. The cooling mist allows higher
light levels for cuttings to photosynthesize while counteracting light's
"evil twin", heat.

Most timing systems on the popular retail market are the "intermatic"
type, with adjustable pegs you can place as on and off switches at
various hours.  I'm afraid I don't know of any off-the-shelf-at-K-Mart
timers that can be programed for the frequent, short duration cycles
needed by a misting system.  If it were me I'd pop for the Phytotronics
Misting Controller or a similar sophisticated unit and consider the
money well spent. There is no way you can have a sucessful hand operated
misting system, unless you have a dedicated employee with a very high
boredom threshhold willing to mist throughout the day! Homer Simpson
comes to mind ("Water on...water off...d'oh!")

Don't mist at night at all, there's no need. The action of mist is to
control water loss in the plant by increasing the ambient humidity and
reducing heat.  The film of water on the leaf evaporates instead of
internal water being drawn out of the plant under high light/heat
conditions. As Al Sleet used to say, "Tonight's forecast:  Dark.
Followed by widely scattered light in the morning hours."

Keep in mind that this reduction in heat translates to the growing
medium, too. Bottom heat may have to be provided to keep the little
roots from getting chilly.

You mentioned household water being used. Keep in mind that water
quality effects the plant's rooting response.  Just for your own peace
of mind, get a water analysis from the city to let you know the
minerals, carbonates, pH, conductivity, etc.  By the way, an elevated
chlorine content, common in city water, isn't all that bad. It can help
control alge and fungus and damping off organisms. And make sure there
is sufficent pressure to make a really good mist, not big droplets out
of your mist heads.

The little thingy that controlls the system automatically is called an
electric leaf. Its just two electrodes set in a block. Water makes
contact and turns off the low voltage solenoid valve. Drying breaks the
circuit and opens the valve.  Be aware that salt build-up on the
contacts conducts electricity. You'll have to clean the thing
periodically for maximum effeciency.

As with everything else in a living system, the frequency and duration
of misting is very subjective, depending on time of day and year as they
relate to temps and lumens in the environment, the transpiration rate of
the plant based on leaf surface area, etc. etc. etc.
At Fullerton College, southern California, we mist every 30 minutes for
30 seconds from first light to about 4 p.m. (Dusk in summer, dark in
winter).  Damping off sometimes becomes a problem, but we still have a
very high success rate for cuttings and seed starts.

Good luck!
Glen Seibert
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