New Greenhouse-advice sought

[Jan Jeddeloh]

For months my husband has spent weekends slaving away on my new greenhouse/alpine house. The greenhouse is 8’x 12’ white aluminum and it’s fully wired.  I’ve got a fan, multiple outlets and lighting for evening work.  And he also put in a hose bib so I’ll have water.  I have two roof vents and three side vents on each side.  The side vents can actually be slid off for even better ventilation.  So yeah, the whole thing is pretty snazzy.  I’ll try to attach some pictures at the end of this post so you can see what I’m talking about but can’t guarantee I’ll be successful. 

So my plan is to put a plunge bed on one side and a regular bench on the other.  The legs for both will be pressure treated 4’x6’ lumber left over from the partial deck remove.  Bench top will probably be about 24” deep made out of wire shelving or some such.  It’s less an issue than the plunge bed.

But before we even get to the plunge bed we have to deal with the floor.  Right now it has some gravel on it but we’d need to add more.  So my floor options are:
1) Gravel alone.
2) Gravel with a paver path down the middle. 
3) All pavers.  My husband would like to use at least some pavers so the bench legs could rest on them.  Size he prefers is “whatever’s easiest”.  He also thinks this would look neater. 
So does anyone have any opinions on the flooring issue?

Next up is the plunge beds.  Pressure treated wood comes in the following sizes: 5.5”, 7.5”, 9.5” and 11.5” x 2” (more or less).  I’d like to use the shortest depth that is reasonable because sand is heavy to haul in and expensive to buy.  I realize that in an ideal world 11.5” would be ideal but wow would that be work and so expensive.  One of my local friends said you also should buy somewhat coarse sand and wash it.  I keep thinking of the work and the weight of wet sand.  Compromises will need to happen somewhere.  So what is the wisdom of the SRGC? 

The plunge beds will be lined with pond liner or some kind of plastic.  If someone has a better idea I’m all ears.  I also need to put in some kind of drain.  I know there is information on the website and elsewhere on line on how to do this but I’d love to hear others’ experience, especially experiences of the “don’t do this” variety. 

Right now I’m envying you Brits who can just buy plunge beds.  Can’t do that on my side of the Atlantic. 

Thanks for your help,
Jan

[annew]

I recommend paving the floor, or at least under the staging legs or you will have problems levelling the staging, especially when fully loaded. Full paving is sweepable, too, unlike gravel which will eventually need removing and cleaning of all the fine dust/compost that builds up in it over time.
The depth of the plunge depends on the size of the pot you want to use - ideally you need 2-3cm of sand under the deepest pot. I use sharp builders' sand (the gritty kind not the bright orange stuff) and put it straight into the plunge without washing. I've had no problems. My plunges vary from 20cm to 15cm in the various greenhouses, depending on the contents. I lined mine with pond liner, lipped over the sides and secured with a strip of wood the same width as the thickness of the sides nailed onto the top edge.

[annew]

Whizzy greenhouse, by the way - have fun!

[annew]

How we constructed our staging (20 years ago and still going strong)

[annew]

Note the cross-ties on the long lengths to stop the sides bowing out under the weight of the sand. The end plunge grades from 15cm deep at the ends to 20cm deep in the middle as it was used as a planted bed before we moved it from our old house, and it was designed to drain from the lowest point. That's a point! it was 10 years at our old place before we brought it here - 30 years and still going strong!
The 'islands' extending into the central path were to make best available use of the space, and we had a second plunge at floor level for shade lovers. I like the high plunge as it brings the flowers nearer to the nose, and allows more efficient use of the space beneath.

[Graeme]

like the greenhouse - never seem to see the opening windows in the UK nowadays

thanks Annew for posting pictures of your greenhouse and benching as it is always really interesting for me to see how other people have configured their benching

I put these on photobucket some years ago for another gardening site when we were discussing benching - one of the alpine houses has a 9" deep sand bed on 4" solid concrete blocks - one of the others has 6" deep but these are sat on 6" plastic water pipe - these were cut to exact length with a circular saw - the floor of the building had a metal 'eye' put into it and a length or reinforcing bar was welded to it - they went over this and were then filled with concrete - basically they are not going anywhere.
The benching just sits on top if it.  Most of the benching I have has galvanised roof sheeting in the bottom to hold the sand or gravel.
http://s343.photobucket.com/user/RowanCottage/library/BENCHING?sort=3&page=1
On the north side of the bottom alpine house there are 3 six foot elite frames mated together - these are raised and to be honest I have never used them yet

Please post more pictures of how you progress as I always like to see how things are going

I will be putting a greenhouse/building thread up next year as our plant area has been on hold a bit this year whilst I built a rather large fence near the house

If you like "raised" beds have a look at this one I built some years ago to get rid of and awkward bank that was no use for anything - I have still not skinned the front with stone as that will be my first job when I retire..........
http://s343.photobucket.com/user/RowanCottage/slideshow/Retaining%20Wall?sort=2

[Tony Willis]

Here is my new 12ft x 8ft greenhouse which I am just completing.

I have six inch deep pressure treated benches lined with polythene (which I have not trimmed off yet) I have deper benches in my other greenhouses but find it is not necessary.

The benches are on a solid floor which is essential because each bench contains 14 - 25 kg bags of sand apart from the pots.

I use builders sand which has been satisfactory for the twenty years I have been growing in clay pots. I find it holds the water better than sharp sand and therefore the pots do not need as much watering.

I fill the space under the benches with sand and use it to store plants dormant over the winter. It is not usable as growing space because it is too dark with the bench above.

This one is housing my crocus collection,spring flowering on the left and autumn on the right

[annew]

Very smart!

[brianw]

Mine was similar to Anne's built from 6" x 1" pressure treated gravel boards, but I used 2 stacked to give a 12" deep box. The box base was 3/4" waterproof ply dropped into the box and supported on battens round the sides and across, leaving a 9" deep plunge. My legs were angle iron fence posts inside the box and bolted through. Pond liner inside lapped and stapled around the top, covering over the iron leg fixings. A 2' x 4' plunge needs 4 legs, longer needs additional legs and the deep plunge needs something to stop bellying as Anne says, although intermediate angle iron legs are strong enough to control this from underneath. This may not happen with a shallow plunge. Try and avoid heavy timbers or masonry if you want to make maximum use of the under bench space, and of course the width of the greenhouse. Ordinary plumbing wastes are fine as a drain. I used sharp sand too.
I had one of these outside the greenhouse for some years too although never made much use of the plunge in that really.

[Jan Jeddeloh]

So based on the unanimous advice on the forum we now have a large stack of pavers waiting for installation. We still don't have enough sand so there will be some more Home Depot (big box hardware store) in our future.  Home Depot is sort of my husband's home away from home. 

My plan is to have a storage shelf underneath the plunge for supplies. The height is going to be custom for me, a 5'2" shorty and even though it will take up space we'll use the 4x6" posts for legs.  It's either use them on site or pay to dispose of them.  I suppose I could box some of it in like Anne did for shade lovers and dormant summer bulbs. I'd also considered some big sand filled tubs for dormant bulbs. I will be getting some 70% shade cloth for the summer but even with that and a fan I expect the greenhouse to be pretty hot in summer.  It's in full, blazing sun.  Temperatures of 30C aren't unusual around here and most summers we even get a handful of days around 35C. 

I'm leaning toward  2x8" or the 2x10" sides for the plunge bed.  I know erythroniums like a deep root run because I always find the bulbs at the bottom of the pots.  Of course this year most of my erythronium bulbs seem to have either desiccated or rotted.  I was repotting them today and discovered the rotten or desiccated remains.  I was used to shady growing conditions where the pots stayed pretty cool.  Shade is pretty much an non-existent commodity at this new place.  I think I'm going to need to learn to grow a lot of things all over again.  Hope the carnage isn't too bad along the way. 

I'm really happy to hear that everyone has used whatever cheap sand they could lay their hands on.  I really wasn't fancying a search for special sand. The simpler we keep this the sooner it will be done.

Jan

[Maggi Young]

5'2"

Small but perfectly formed, Jan! 

[Jan Jeddeloh]

Actually anymore I'd say I'm "fatly formed"!  My husband is 6'2" so I always have to make sure he doesn't build/place something too high.  I'm described as "vertically challenged" by the rest of my family (daughter 5'7", son 6', husband 6'2". 

Jan

[Maggi Young]

Don't tell anyone - but I'm a practically spherical 5 ft 3inches ..... and a half!

[annew]

Both taller than me. It is an advantage, as I know, to have a husband over 6ft! No point in using the top shelves of cupboards otherwise for a start!

[Yann]

Finding plunge outside UK can be impossible so i selfmade mines.

I've used reinforced aluminium foil bent with a rented machine. For the corners i used pop rivet, pre-drilling holes.
The cost price is +/- 30€ per tub 2.2mx0.9m. Since, i've learned how to weld aluminium and outside i now use this tub for my seedling pots with a more important height.

This aluminium can support 2.6t/sqm. I fill the bed with pumice to reduce weight on the cedar benches.