hot bed propagator

[deb of the wych]

Hi I need some advice about the hot bed propargator (dont know if thats the right name) I have built with soil warming cables in sand.
what I need to know is should the sand be kept damp or not

deb

[sewer rat]

Deb
No need to keep the sand damp at all

[deb of the wych]

Thanks SR
I'm at a total loss with this modern technology but I must admit it is great to use.
deb

[nick the grief]

Your better to keep the sand damp Deb as it's the water that conducts the heat & it will be more even than if you don't. To stop it drying out cover it with a black bin liner or if it's bigger than that some black plastic.

I've got some membrane on mine as well and Just water this now and again to keep the moisture level up.

In the summer you can let it dry out & then come the winter give it a water of tap water and bleach at about 5% strength and that will steralise the sand of any nasties that may have built up.

[sewer rat]

Nick
Now I know why you are our guru - I will pass this on to the head Gardener of the estate where I was renovating the castle - he never damped his hotbox down at all !!!! Never having had one (yet) I was only speaking or replying from what I had sen and not actually done. I assumed because someone had the title of Head Gardener of a Highland Estate, that they would know what they are doing

Deb, sorry for the mistook, please accept my grovelling apologies

[nick the grief]

Thats Ok Rat, sack him & give me the job Sand is an insulator so it will only get hot around the cable, the water will transfer heat better.

If I get shance I'll take a foto of mine tomorrow ..... & if your really lucky I'll show you the hot bed as well

[nick the grief]

Luckily I have some foto manipulating software LJ

[Snadger]

Luckily I have some foto manipulating software LJ

I told you LJ, gardeners tools Hoe, rake,fork, spade and photo manipulating software!

[Pippin]

Here are a couple of pictures of my heated propagator which I took to add to my website, I built it 25yrs ago. It is still going strong. Nick is right in that water is essential for all the reasons he gave. I changed the sand for peat a couple of years ago though after reading how Alan Titchmarch propagates his cuttings and seeds this way.

He plants his cuttings straight into the peat and of course the seed trays and pots can go on top as usual. I still keep the sand to bed the cables onto. I personally have found it better.

I have added a few images below of the propagator in action last year and its preparation for this year. There is a cover that I place on top.

Hope you don`t mind the steal on the images Nick - I would certainly like to see yours.

Pippin

[deb of the wych]

Thanks for all your help
Pippin yours looks great. The one I have got at the moment is on loan from my sister as she is moving house so hasn't got anywhere to put it It is built with an aliminium frame but next year I am planning to build my own.
Looking at the thermostat on this one It is really just a rod thermostat. Has anyone tried making one with a hot water tank rod thermostat that costs only �10 rather than �30 for brandnamed one.

deb

[Pippin]

Has anyone tried making one with a hot water tank rod thermostat that costs only �10 rather than �30 for brandnamed one.

It would be possible Deb but you can`t put a price on safety - remember water is going to be involved and it is a good conductor of electricity (I`m a self employed appliance engineer and ex electrical engineer in the royal navy ). You need to know what you are doing - not just for your safety but for family and friends also.

Pippin

[nick the grief]

I agree with Pippin. Also you have to consider the accuracy of the thermostat If the water heats up by a few degrees it won't matter It could frazzle your seedling however. Also are you sure that imersion stats are rod type? ours was strapped to the out side of the tank

[deb of the wych]

Hi thanks for your advice

I understand the safety aspect as I'm a elec + electronic engineer ( thats why I can't spell) the thermostat I'm looking at is in farnell (0 to 40 centigrade) and of course I would enclose the electrical connections in waterproof housing
just wondered if anyone had tried it before

deb

[Pippin]

Hi Deb,

Grate to here! .

Why not give it a go. You would need one to protrude into the `box` by about 9-12" - if it was more I don`t think it would matter.

You can always check the temp settings by using a thermometer. I use an old beer brewing thermometer I got from Boots years ago - its just a straight glass rod about 14" long, great for measuring my compost heap temps.

Put about 2" of sand or peat over the cables - and under the cables (I only use sand for under - make sure it`s horticulteral quality sand).

Turn the stat to say 10C leave it for a couple of days to stabalise then check the temp by pushing the thermometer about an inch under the peat or sand.

Gradually move up the scale of the stat maybe every 5C (this will have to be done over a couple of weeks maybe as each setting stabalises) to about 30C and note what the soil temps are at each 5C rise and also the air temps (just place thermometer on the surface) and make a note along side each stat setting.

You will only need to do this once. All stats can have a 10% tolerance - sometimes more.

But this way you will be reasonably certain of what your propagator temperatures are according to what you set the stat .

Clear as mud - eh!

Pippin

[deb of the wych]

Thanks pippin Ill give it a try

Ill let you know how I get on but I wont start till summer when my sister wants hers back
At the mo I'm using one of those digital indoor/outdoor thermometers and putting the probe (thats supposed to be threded outdoors) into a pot of soil so i can get a reading of air temp and soil temp in propagator also shows min temp at night and max temp during day
only cost a fiver so was a bargain

deb