On Tue, 26 Oct 2004 09:00:05 -0700, wrote
(in article ):


Shouldn't be too hard to find. I can recommend the one at Charley's
Greenhouse for 69.95.

Tom
Walnut Creek, CA
Nikon CP 5700

On Tue, 26 Oct 2004 09:00:05 -0700, wrote
(in article ):


Shouldn't be too hard to find. I can recommend the one at Charley's
Greenhouse for 69.95.

Tom
Walnut Creek, CA
Nikon CP 5700

My mentor just bought a millivolt one at Home Depot $25(RightAid brand)sp?
He said it works like a charm that the only downfall, if you will,
is that it has batteries to run the digital program.
He has been growing orchids in a g/h for over 50yrs & has had one
thermostat all that time. Maybe we should be looking into
that manufacturer? *g*

--
Cheers Wendy

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wrote:
Does anyone have a source for a waterproof programmable termostat for
a greenhouse that can control a 110v heater?

My mentor just bought a millivolt one at Home Depot $25(RightAid brand)sp?
He said it works like a charm that the only downfall, if you will,
is that it has batteries to run the digital program.
He has been growing orchids in a g/h for over 50yrs & has had one
thermostat all that time. Maybe we should be looking into
that manufacturer? *g*

--
Cheers Wendy

Remove PETERPAN for email reply

wrote:
Does anyone have a source for a waterproof programmable termostat for
a greenhouse that can control a 110v heater?

Of course it depends on what you grow but I live in Seattle (similar
weather) and have my thermostat set for just under 60...

wrote in message
...
Thank You Ray!
In my gh that is almost what exactly happens. During the winter I
rarely see temps over 75, which are quite common in summer inspite of
the cold location. The gh is heated only to 70 in the winter and on
some days the temps do not reach even that. The plants, as you state,
do quite well.

On Wed, 27 Oct 2004 08:56:46 -0400, "Ray"
wrote:

Think of "on the cool side" this way: if your plant can typically be
expected to see daytime temperatures between 65°F and 85°F, for the same
light intensity, growing it at 70° will give "better" plants than if they
are grown at 80°. Let me explain the (probably oversimplified) logic.
Please keep in mind that these are generalities, and the applications to
individual plants is quite varied.

More light results in greater generation of food and energy, and their
assimilation into the plant. Higher temperatures result in faster
metabolism, hence growth, with the accompanying consumption of those
reserves.

The application of more light intensity, however, is accompanied by
increased localized heating of the plant tissues, and too much can be bad
for the plant, even if not outright damaging. By having the environment
be
a bit cooler, it offsets that heating effect to a degree.

If we consider that the plant's metabolism will also be reduced by the
cooler temperatures, we can see that those conditions will give the plant
an
opportunity to benefit from making and storing more reserves while
expending
less on vegetative growth - hence a sturdier plant that has more energy
for
blossoms.

I also am aware of (but will not claim to "know" anything about)
differences
in tissue growth rates effected by light levels - cell walls thicker in
higher light, cells elongated and thinner-walled in low light - which
explain the "soft and leggy" comment I made in an earlier post, but I'm
sure
there's someone else out there who can explain that better than I.

Of course it depends on what you grow but I live in Seattle (similar
weather) and have my thermostat set for just under 60...

wrote in message
...
Thank You Ray!
In my gh that is almost what exactly happens. During the winter I
rarely see temps over 75, which are quite common in summer inspite of
the cold location. The gh is heated only to 70 in the winter and on
some days the temps do not reach even that. The plants, as you state,
do quite well.

On Wed, 27 Oct 2004 08:56:46 -0400, "Ray"
wrote:

Think of "on the cool side" this way: if your plant can typically be
expected to see daytime temperatures between 65°F and 85°F, for the same
light intensity, growing it at 70° will give "better" plants than if they
are grown at 80°. Let me explain the (probably oversimplified) logic.
Please keep in mind that these are generalities, and the applications to
individual plants is quite varied.

More light results in greater generation of food and energy, and their
assimilation into the plant. Higher temperatures result in faster
metabolism, hence growth, with the accompanying consumption of those
reserves.

The application of more light intensity, however, is accompanied by
increased localized heating of the plant tissues, and too much can be bad
for the plant, even if not outright damaging. By having the environment
be
a bit cooler, it offsets that heating effect to a degree.

If we consider that the plant's metabolism will also be reduced by the
cooler temperatures, we can see that those conditions will give the plant
an
opportunity to benefit from making and storing more reserves while
expending
less on vegetative growth - hence a sturdier plant that has more energy
for
blossoms.

I also am aware of (but will not claim to "know" anything about)
differences
in tissue growth rates effected by light levels - cell walls thicker in
higher light, cells elongated and thinner-walled in low light - which
explain the "soft and leggy" comment I made in an earlier post, but I'm
sure
there's someone else out there who can explain that better than I.

If you find one, let me know. I bought a standard programmable one and gave
up the ghost in less than a year. You can "make" one by taking 2
thermostats and 1 timer, put the timer in series w/ one thermostat then put
the two in parallel with the other thermostat...

I was gonna do that but ended up just buying one thermostat and setting it
at 60 and leaving it at that. Occasionally I'll manually turn it up to 70
in the day if for example I water expecting a bit of sun to dry things and
it doesn't happen or if we get lots of no-sun days in a row.

wrote in message
...
Does anyone have a source for a waterproof programmable termostat for
a greenhouse that can control a 110v heater?

Just another data point. We run with two heating set points. But the
criteria for which one is in effect is not the time of day, but the amount
of light in the greenhouse. Nights and cloudy days get the lower set point
temp and the brighter light (above 1000 foot candles) is given a set point
of about 5 - 8 degrees higher. In most cases the normal warming of the sun
is enough to warm the greenhouse to the light set point. But on really cold
days when the heat lost is greater than the solar gain, the second set point
kicks in. For my greenhouse in Va, the second set point becomes important
when outside daily high temps are somewhere in the low teens or single
digits (the wind plays a big factor). Some of my greenhouse are computer
controlled and they take care of themselves. In the other greenhouses, I
just bump the thermostat up for three or four hours in the middle of the
bright very cold days. The need for the light set point is just not needed
very often here and I am in a colder location than Ray. But if I was
putting up a greenhouse in say MI, this could be much more important.

Pat

"Ray" wrote in message
...
Ah HAH! Where you are living plays no role in my analysis of the
situation, but that "minor detail" of the HPS lighting makes a big
difference!

As to the light versus temperature thing, you're right that at some point
it's just too cold, but growing most plants on the cool side of their
normal temperature range with high light levels will actually give
fantastic results. Not that I am capable of that on a regular basis, mind
you...

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!
.
wrote in message
...
Ray,

Thanks for the comments.

Here in Vancouver BC if I would let the solar heat do my heating for
me during the winter I would be looking at growing just Cymbidiums and
even then marginally. As my gh is on the north side of the house, in
winter partially shaded by the house, on a property that is the second
highest point in Vancouver, you can see why I need to raise my
temperatures to some realistic figures Also I use HPS lights during
the winter. I agree with you that light is more important than
temperature except when the temperature is too low. If the plants are
too cold then no amount of light will make them grow.

The reason I want a programmable is that so I can set the max, but
more importantly the minimum temperature so in case it gets very cold
I can have three heaters running instead of just two as I do now using
single point thermostats and timers.



On Tue, 26 Oct 2004 17:34:14 -0400, "Ray"
wrote:

After more than 30 years of orchid growing, I still vote with
"old-timers"
that taught me way-back-when, and support NOT artificially raising the
daytime temperature of greenhouses, but letting solar heat gain do the
work.

Light is a more important factor to healthy plant growth than is warmth.
Artificially warming the GH on gray days will result in leggy, soft
growth
that in extreme cases cannot support its own weight, let alone that of
added
blossoms.

Save your money and buy a single-setpoint thermostat, set it to the
minimum
temperature you'd like your plants to experience, and let it go at that.