bit late for this year I suppose, but I have a thermostat and a length
of plastic wired with heating cable which I keep meaning to make into
a proper heated seedbed. Does anyone have any advice / plans for doing
this properly? Many thanks

NogbadtheCool wrote:
bit late for this year I suppose, but I have a thermostat and a length
of plastic wired with heating cable which I keep meaning to make into
a proper heated seedbed. Does anyone have any advice / plans for doing
this properly? Many thanks
Make a 6 inch deep frame with an OSB or WBP ply base (threequarter inch
thick base because it will have to support a few kg of sand). Put a
layer of polystyrene or kingspan insulation in the bottom. Line with
thick plastic sheet. Follow the instructions for your soil warming
cable - generally 1 inch sharp sand, then the cable, then another inch
or two of sand. You can drill through the sides for the cable and
thermostat. Make sure that the legs are sturdy and braced if it is not
wedged in place

I built one like this a number of years ago and sized it so that an
aluminium cold frame would fit on top. This gives growing height and
when shut down at night can be cobered with bubble plastic to help with
insulation. Mine is in an unheated greenhouse and the air temp has
never gone below 5C.

Malcolm

On 14 Mar, 13:52, NogbadtheCool wrote:
bit late for this year I suppose, but I have a thermostat and a length
of plastic wired with heating cable which I keep meaning to make into
a proper heated seedbed. Does anyone have any advice / plans for doing
this properly? Many thanks

this may sound unusual, but are heated waterbed mattresses still being
sold over there? I had the idea to use my California King size
waterbed at one point as a heating seed bed. The pad that they make
for heating the waterbed's is remarkable. It never gets too hot, but
provides an even and low distribution of heat that eventually heats up
quite a large bit of water, and it always has a thermostat on it to
put it at the temperature you want it. It worked quite well for the
time I was able to employ it. I didn't completely fill up the huge
mattress with water, but half filled it and had it sitting inside a
make shift frame (not unlike the actual waterbed frame) and before
half filling the mattress, I positioned the waterbed heater underneath
it. ) Since the mattress wasn't completely filled, it heated quicker,
but provided good distribution of heat through the warm water to the
seed flats that I just sat on top. And the added bonus was it was a
waterbed mattress made out of incredibly puncture resistant vinyl with
reinforced edges. I hate I had to leave it behind! Even having a
single sized waterbed mattress would be easier to maintain in a small
area for seed germination and plant coddling until it's time to plant
them out and harden then. Just a suggestion. I thought about actually
going to a Charity shop for a used but still functional water bed
mattress and heating pad.

just an odd thought........
maddie stepping behind the boxwood in West Tennessee

madgardener wrote:
On 14 Mar, 13:52, NogbadtheCool wrote:
bit late for this year I suppose, but I have a thermostat and a
length of plastic wired with heating cable which I keep meaning to
make into a proper heated seedbed. Does anyone have any advice /
plans for doing this properly? Many thanks

this may sound unusual, but are heated waterbed mattresses still being
sold over there? I had the idea to use my California King size
waterbed at one point as a heating seed bed. The pad that they make
for heating the waterbed's is remarkable. It never gets too hot, but
provides an even and low distribution of heat that eventually heats up
quite a large bit of water, and it always has a thermostat on it to
put it at the temperature you want it. It worked quite well for the
time I was able to employ it. I didn't completely fill up the huge
mattress with water, but half filled it and had it sitting inside a
make shift frame (not unlike the actual waterbed frame) and before
half filling the mattress, I positioned the waterbed heater underneath
it. ) Since the mattress wasn't completely filled, it heated quicker,
but provided good distribution of heat through the warm water to the
seed flats that I just sat on top. And the added bonus was it was a
waterbed mattress made out of incredibly puncture resistant vinyl with
reinforced edges. I hate I had to leave it behind! Even having a
single sized waterbed mattress would be easier to maintain in a small
area for seed germination and plant coddling until it's time to plant
them out and harden then. Just a suggestion. I thought about actually
going to a Charity shop for a used but still functional water bed
mattress and heating pad.

just an odd thought........
maddie stepping behind the boxwood in West Tennessee

Why not just an ordinary electric blanket? But Nog has the heating
element already, so we're both out of the loop.

--
Mike.

On Sun, 14 Mar 2010 11:52:25 -0700 (PDT), NogbadtheCool
wrote:

bit late for this year I suppose, but I have a thermostat and a length
of plastic wired with heating cable which I keep meaning to make into
a proper heated seedbed.

Don't believe its to late, my three will be in full use for the next
six weeks at least.

Previous posts are correct, but I also line mine with that reflective
thick foil to keep the heat in, also the sand MUST be kept damp for
the cables to work correctly, some can burn out if they get dry.

So Heavy damp sand, hence the weight problem.
And to keep the sand really damp, cover the surfuce with a sheet of
polythene, otherwise you will be having to constanly re wet.

Mike Lyle wrote:
madgardener wrote:
On 14 Mar, 13:52, NogbadtheCool wrote:
bit late for this year I suppose, but I have a thermostat and a
length of plastic wired with heating cable which I keep meaning to
make into a proper heated seedbed. Does anyone have any advice /
plans for doing this properly? Many thanks
this may sound unusual, but are heated waterbed mattresses still being
sold over there? I had the idea to use my California King size
waterbed at one point as a heating seed bed. The pad that they make
for heating the waterbed's is remarkable. It never gets too hot, but
provides an even and low distribution of heat that eventually heats up
quite a large bit of water, and it always has a thermostat on it to
put it at the temperature you want it. It worked quite well for the
time I was able to employ it. I didn't completely fill up the huge
mattress with water, but half filled it and had it sitting inside a
make shift frame (not unlike the actual waterbed frame) and before
half filling the mattress, I positioned the waterbed heater underneath
it. ) Since the mattress wasn't completely filled, it heated quicker,
but provided good distribution of heat through the warm water to the
seed flats that I just sat on top. And the added bonus was it was a
waterbed mattress made out of incredibly puncture resistant vinyl with
reinforced edges. I hate I had to leave it behind! Even having a
single sized waterbed mattress would be easier to maintain in a small
area for seed germination and plant coddling until it's time to plant
them out and harden then. Just a suggestion. I thought about actually
going to a Charity shop for a used but still functional water bed
mattress and heating pad.

just an odd thought........
maddie stepping behind the boxwood in West Tennessee

Why not just an ordinary electric blanket? But Nog has the heating
element already, so we're both out of the loop.


Be very careful with this idea - ordinary electric blankets aren't
intended to get wet. Having said that, take precautions with any use of
electricity around water (as in a greenhouse) - at the very least one of
those plug-in safety devices that will cut the power in the event of
problems...

Adrian

Adrian Brentnall wrote:
Mike Lyle wrote:
[...]

Why not just an ordinary electric blanket? But Nog has the heating
element already, so we're both out of the loop.


Be very careful with this idea - ordinary electric blankets aren't
intended to get wet. Having said that, take precautions with any use
of electricity around water (as in a greenhouse) - at the very least
one of those plug-in safety devices that will cut the power in the
event of problems...

You're quite right: homicidally stupid of me not to think of that.

--
Mike.

On Mar 15, 10:30*pm, "Mike Lyle"
wrote:
Adrian Brentnall wrote:
Mike Lyle wrote:
[...]

Why not just an ordinary electric blanket? But Nog has the heating
element already, so we're both out of the loop.

Be very careful with this idea - ordinary electric blankets aren't
intended to get wet. Having said that, take precautions with any use
of electricity around water (as in a greenhouse) - at the very least
one of those plug-in safety devices that will cut the power in the
event of problems...

You're quite right: homicidally stupid of me not to think of that.

--
Mike.

thanks for that everyone - I'm not clear why the sand has to be wet,
doesn't the heat dry it anyway? And should the thermostat be in the
sand or near the seedbed? I'll probably put three little propagators
on the top to hold the pots etc and assumed the thermostat would go in
one of them. Cheers

thanks for that everyone - I'm not clear why the sand has to be wet,
doesn't the heat dry it anyway? *And should the thermostat be in the
sand or near the seedbed? I'll probably put three little propagators
on the top to hold the pots etc and assumed the thermostat would go in
one of them. Cheers- Hide quoted text -

- Show quoted text -

The reason for the sand being damp is so they the heat will spread
through the bed, dry sand is a very good thermal insulator and that's
not what you want in a heated bed.
If you place a sheet of polythene on top of the sand it will keep the
moisture in the bed and will prevent the roots from the pots, trays
etc from geting into the sand.
David Hill

On Thu, 18 Mar 2010 03:19:15 -0700 (PDT), NogbadtheCool
wrote:

And should the thermostat be in the
sand or near the seedbed?

Depends on the type, some have probes that are inserted into the sand,
others are next to the seedbed. And there is the other type that don't
use a seperate thermostat

on the top to hold the pots etc and assumed the thermostat would go in
one of them.

Don't forget the more you use the seedbed, ie: fill it with pots, that
keeps the heat in and so, the running costs are kept down.