New bulb trial beds finished!

[annew]

At last I've finished construction on my new sand beds for planting out bulb seedlings for assessment. The beds themselves were finished in time to plant the bulbs, but the superstructure and covers took a while longer.
The boxes are made of 22mm tanalised timber. Each bed is 4.8m long x 80cm wide and 45cm high. The stop the sides bowing out when filled, they were braced with copper piping.
The base is lined with a porous membrane, and the sides with insulation boards, covered with pond liner, held in place with battens at the top and sealed around the pipes.

[annew]

10cm large gravel went into the bottom to break capillary connection with the ground (it's very wet here), then another layer of membrane. Next a 15cm layer of topsoil, then 10cm sharp builder's sand. On top of this are laid soil warming cables for emergency use only if temperatures plummet. Finally another 20cm sand.

[annew]

The covers are polytunnel polythene supported by 20mm PTFE water pipe, held down by webbing straps looped onto hook-eyes using bungees.
I had a problem with the straps slipping off the end hoops, so solved this by adding a second hoop to each end and rivetting a 12cm wide strip of 2mm polycarbonate between them, and running the strap over this.
The sides can be rolled right up to the ridge for working, halfway for ventilation with bird/cat netting. or all the way down in severe weather., when there are also end covers of 3mm polycarbonate sheeting.
Just need the cables connecting now (not my job)!

[Graeme]

very impressive - will be interested to see the results in due course - just two questions why the copper pipe? are you fitting a watering system?

[Yann]

whaou, well done Anne! what's the power of the heating cable?

[annew]

The copper pipe is just to brace the sides to stop them bowing outwards. The cables are 300W each.

[mark smyth]

very exciting

[Jan]

Good idea, but the execution is not good. You will have problems. I do so I grow bulbs 35 years.

[Graeme]

Good idea, but the execution is not good. You will have problems. I do so I grow bulbs 35 years.

Jan - can you post some more pictures of the outside of those frames? - are they block built with dutch light frames above?
Thanks

[Jan]

I'll try to find a photo and write what I see the problem. OK? But it will not be today.

 

[Yann]

Jan have you got my pm? sorry to write this here...

[annew]

Wow, Jan! You are much bigger! If you can tell me the problems, maybe I can fix it.

[johnralphcarpenter]

Won't those layers create a perched water table, impeding drainage rather than helping it?

[annew]

Hope not. Seems OK so far!