Cover for a hot bed

**Aberdeenplotter** · 07-01-2019, 11:02 PM

I'm trying to envisage the finished article. You digging out a hole to fill with horsemuck or similar and then covering with soil at ground level?

**mcdood** · 08-01-2019, 07:01 AM

I think polythene would give you a condensation problem. I'd go fleece as should be warmer than enviromesh depending on the quality while still allowing the plants to breathe.

**Penellype** · 08-01-2019, 08:07 AM

I use polythene, but my hotbeds are outside. It does produce condensation, which is an issue in any enclosed environment at this time of year. You can always open it up on warmer days for a change of air.

Bearing in mind the low light levels at this time of year I would be inclined to prefer mesh to fleece, but I'd be using the white kind, not coloured. The greenhouse will help to keep some of the cold out anyway.

**Snadger** · 08-01-2019, 08:52 AM

Fleece or enviromesh will not retain heat the same as polythene or glass but the latter will give condensation problems.

I would think that whichever method you chose, the whole greenhouse would be dripping wet all the time.

**Derbydal** · 08-01-2019, 09:13 AM

would the cheap black weed surpressant stuff do the the job ? and it may wick the water back down into the hoss muck, also it may absorb heat from whatever day light you get in the greenhouse ! atb Dal.

**rary** · 08-01-2019, 03:50 PM

Originally posted by Aberdeenplotter View Post

I'm trying to envisage the finished article. You digging out a hole to fill with horsemuck or similar and then covering with soil at ground level?

I have possibly named it wrong, I will be filling a box with a sand compost mix and burying an electric heating cable in it, it will be large enough for seed propagation and also to grow on some plants

**4Shoes** · 08-01-2019, 04:32 PM

I've seen a few posts with a box frame 1.2m x 1.2m (4' x 4') back filled with muck and topped off with compost and sand to give a hot bed. When these are in Polytunnels, they finish off the top with a frame and hoops to form a mini polytunnel.

i.e. you end up with a hot bed between 600 and 900mm high, with 2 hoops over the top smaller frame 1.2 x 1.2. You just list this one off to gain access. Same basic idea as the blue pipe question posted yesterday.

edit.
You could use same basic concept for you soil warming cable. I was thinking of this, but didn't think temperature in greenhouse would be high enough to keep air temperature in the warm bed high enough over night.

**Jungle Jane** · 08-01-2019, 05:00 PM

For seed germination polythene would be best for warmth & keeping the temp & moisture nice. If the condensation gets too much you could adjust things or change to fleece later,sounds good for an early start

**Deano's "Diggin It"** · 08-01-2019, 05:12 PM

Originally posted by rary View Post

I have possibly named it wrong, I will be filling a box with a sand compost mix and burying an electric heating cable in it, it will be large enough for seed propagation and also to grow on some plants

Otherwise known as a heated propagation bench!

An hot bed is an entirely different concept, but know where your coming from

Gis a mo!

https://m.youtube.com/watch?v=wwkGXEatKSk

https://m.youtube.com/watch?v=Rf36owOCjPw

These are worth a neb at!

**Chestnut** · 08-01-2019, 05:15 PM

I have never built a hotbed, but intend to try this year, so I am interested in everyone’s thoughts. Instinctively I would go with fleece inside the GH, but I don’t know if that’s right.
Might just be a memory of a book I read about growing winter veg (I think CDowding) which describes a system of fleece over plants inside polytunnels....

**Aberdeenplotter** · 08-01-2019, 08:38 PM

My heated bench sits on top of my workbench in the garage. It is three full sized seed trays long and three full sized trays wide. i.e. it can hold 9 full sized seed trays. The bottom and sides are made of �" ply the sides being 6" deep.The bottom is lined with thick clear polythene (colour not material). I then have an inch or so of damp sharp sand on which my heating cable is placed. Then another inch or so of sand and then another layer of polythene (to stop the sand drying out). I have the heating cable attached to a rod thermostat and set to 18�c. Finally I have the whole surface covered with capillary matting which is kept moist. I find this helps keep the temperature uniform across the bench.

**Aberdeenplotter** · 08-01-2019, 09:03 PM

OOps forgot to say. I have an 8 tube t5 growlight over.

**SarrissUK** · 08-01-2019, 10:20 PM

That sounds a great setup AP... I wish I had room for that somewhere.

**rary** · 08-01-2019, 10:35 PM

Originally posted by Aberdeenplotter View Post

My heated bench sits on top of my workbench in the garage. It is three full sized seed trays long and three full sized trays wide. i.e. it can hold 9 full sized seed trays. The bottom and sides are made of �" ply the sides being 6" deep.The bottom is lined with thick clear polythene (colour not material). I then have an inch or so of damp sharp sand on which my heating cable is placed. Then another inch or so of sand and then another layer of polythene (to stop the sand drying out). I have the heating cable attached to a rod thermostat and set to 18�c. Finally I have the whole surface covered with capillary matting which is kept moist. I find this helps keep the temperature uniform across the bench.

My bench would hold 20 trays but don't envisage having that many at the one time, so will be using part of it to grow on some pot plants, I have never thought of the second poly layer but like the idea as it would help maintain the temperature, and hold the moisture around 5he cable (I have had a bench dry out and go on fire, it was peat that I had been using rather than sand) do you have the capillary matting drawing from a reservoir or do you wet it down with a watering can

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