Coldframe - Winter insulation advice

Posts

• nick615 Posts: 1,487

  October 2023

  Presumably anything to stop the insulation freezing into a hard wet lump would be an advantage but, if you can source any biggish plastic bags, e.g. bird food or farm fertiliser, they could be sealed together into a tube using mastic, thus encasing the insulation completely.

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• Dovefromabove Posts: 88,147

  October 2023

  Don’t forget the need for adequate ventilation.., you don’t want your plants rotting … its a fine line to tread .., 
   

  
  Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
  
  
  
  
  
  

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• McRazz Posts: 440

  October 2023

  TerrysWorld said:

  After last winters hard frost and losing some plants in the coldframe.
  
  My coldframe is made 150 x 22 gravel boards some 8yrs ago. Over the seasons the boards have shrunk leaving small gaps board to board. I found a spare roll of loft insulation. I thought of using this to insulate the inside of the frame side then covered with bubble wrap. The lid is made with an old double-glazed unit.
  
  My question, because of the gaps between the boards should I lay a membrane against the boards before laying the insulation or not bother. 

  I'd personally avoid loft insulation as its designed to be laid flat in a relatively dry and sheltered environment. Not only could it attract and hold moisture which obliterates its thermal conductivity value (K value), but its also the perfect material for rodents to borrow into (as has happened in my garage).
  
  An extruded insulation board is probably better suited, something like Recticell, Kingspan, or similar - Wickes will be your place to buy this.  

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• Fairygirl Posts: 55,117

  October 2023

  Cold frames only offer minimal protection, and are ideal for overwintering hardy plants that are too small to plant out, or for starting off hardy annuals etc. Anything half hardy would need far more protection. Damp cold is far more of a problem than dry cold - same as plants in the ground. 
  It's not suitable for anything that needs to be dry and/or have warmth. I can't store anything like dahlias or cannas for example, in a cold frame or cold greenhouse because it's simply too damp for them.  They'd need to be in the house. In drier areas, you might get away with some fleece over plants, but it would always be hit and miss. 

  It's a place where beautiful isn't enough of a word....
  
  
  
  I live in west central Scotland - not where that photo is...

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• TerrysWorld Posts: 174

  October 2023

  Thanks all,
  main reason for doing this I’ve have young cuttings potted on. Although perennials Salvia’s and others as not let the frost kill them off.
  I dont have a greenhouse, but have a shed. Last winter had my Tree fern stored, and had burnt fronds. 

  South Monmouthshire stuck in the middle between George and the Dragon

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• thevictorian Posts: 1,279

  October 2023

  They cultivate aquatic plants emersed in rock wool which is the same as loft insulation and it's very good at holding onto water, so not something that I think would make a great option as outside insulation no matter how well sealed it is. 
  It might be easier to just cover the plants with some horticultural fleece on the coldest nights and take it off when the weather is warmer. With that you get a little extra protection in the cold frame and you also grow the plants harder which will help longterm. 

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