Need advice on greenhouse setup

[FaeLLe]

Hello all,

So I am in a position where I need to move the location of all my plants from indoor to outdoor, they have been living forever under 1000W grow lights all year long.

Now the only location available to me is to put it on top of my deck (an 8x6 glass greenhouse aluminum frame) and run gas heaters there.

Would appreciate any thoughts on the following please as I have never had an outdoors greenhouse,

1) Any concerns you can see by me placing the greenhouse on my deck which was installed a year ago (I understand in a few years it might break down but happy to rearrange in 5 years or so)
2) Can someone recommend a gas heater to use?
3) What is the minimum temperature I should consider, 8 or 10 C ? given I have a lot of caudex plants

Any guidance you can provide is appreciated as I plan to do the entire work this weekend.

Some pictures below,

Deck on top of which I want to arrange the greenhouse

[JaneO]

Hi,
I would have thought the decking would be lethal for walking on when wet? Slippery. Would you put something down on decking to avoid breaking your neck? Not sure what. I'm sure there will be more difficulties. Could you not remove decking and concrete the base?

[FaeLLe]

Hi,
I would have thought the decking would be lethal for walking on when wet? Slippery. Would you put something down on decking to avoid breaking your neck? Not sure what. I'm sure there will be more difficulties. Could you not remove decking and concrete the base?

Trying to go about it the least disruptive way... though I am happy to rework the entire gig in a few years.

Would there be any growing condition implications?

[MikeT]

The greenhouse will need fixing to the decking, either directly, or a base fixed to the decking and the GH fixed to the base. Where the decking has base/GH fixed, it will tend to remain wet for prolonged periods after rain/snow, and will rot much faster than if having free airflow around it. Much better, and less work in the long term, to take up some of the decking and have a permanent base for the GH.

[FaeLLe]

The greenhouse will need fixing to the decking, either directly, or a base fixed to the decking and the GH fixed to the base. Where the decking has base/GH fixed, it will tend to remain wet for prolonged periods after rain/snow, and will rot much faster than if having free airflow around it. Much better, and less work in the long term, to take up some of the decking and have a permanent base for the GH.

Thanks Mike and others. Any suggestions on a heater to use for this size? Don’t want to mess with electrics...

[Eric Williams]

Hi, some nice plants under lights. Cannot advise on g/h, but electric would be far more pre fable to gas in all respects. You could go down to 7'C for many plants and put the sensitive ones back under lights for the Winter. Cheers

[Diane]

I think it would be very short-sighted to build an 8 x 6 greenhouse on decking. You should view a green house as a permanent structure, not something that can be "re-worked" in a few years' time, I would foresee all sorts of problems with that idea. There will be a considerable amount of weight to be supported when you include staging and plants, which might be more than the decking is capable of supporting, regardless of possible rot problems in the future. It would be pretty catastrophic if you woke up one morning to find the whole structure collapsed through the decking! So my advice would be to take the decking up, and build the greenhouse on a solid base on the ground.
I would also advise against a gas heater even if it seems the easiest option at the moment. I used a gas heater for many years about 30 years ago, and it entailed running two gas bottles with an exchanger unit to protect against running out suddenly in a cold snap - an exchanger is quite an expensive bit of kit to purchase. Then you have to have a gas bottle supplier to deliver (the large bottles I used were extremely heavy to manoeuvre). There is also the problem of condensation with gas - it gives of approx. 5 litres of water vapour for every kg of gas burnt - not really what you want with cacti and succulents. Far better to get a quote from an electrician for running cable to the greenhouse - a good electric heater with a digital external thermostat would be a much better option and probably cheaper to run, plus giving much more accurate temp control.
Just my thoughts!

[ralphrmartin]

(1) How long will that decking last, especially if lost of water gets on it from watering the plants? It may rot more quickly at the higher temperatures inside the greenhouse. Seriously, I agree with the people who say to put down concrete.
(2) If using a gas heater, use one with a flue, so the water produced as a result of combustion does not vent inside the greenhouse in winter, which would lead to very high humidity. Most people use electric heaters for this reason.
(3) For a general collection, a minimum of 5C would work. For caudex plants, maybe 15C is more appropriate. What you could do is still keep some of the most tender ones inside the house.
(4) If the decking is slatted with gaps, you might lose quite a bit of heat between the slats.
(5) It looks like it will be shaded by the house -> Consider moving house first!

[Chris L]

I am another one for the removal of the decking and a concrete base in it's place. A glass/metal greenhouse + wet pots full of gravel and soil is very heavy.

Screws into soft wood will not hold should the greenhouse decide to move in strong winds.

[Phil_SK]

I wouldn't put a greenhouse on decking. The close contact of the frame and the decking will mean that some areas won't dry out and the wood won't last nearly as long. The effort of changing everything around - when it's full of plants - will be far greater than doing it right first time. That said, I've never felt the need to create a concrete slab: good greenhouses have built in bases (a chunkier bit of aluminium) that you fix by cementing into holes in the ground at strategic points. Thick polythene topped with the heavier, woven landscape fabric is good enough to keep the bulk of the moisture in the earth below from evaporating into the greenhouse. It'd make things easier if you decide to move house and take g/h with you or position it somewhere else or you lose interest and decide you want your garden as a kiddie football pitch in the future.