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Plants and snow and the Hardiness rating

JamesOJamesO Posts: 230



I have a few plants that are in the H3 zone 1 to -5 tonight it is around 1 to +2 but snow has started to fall and the layers are forming in the beds.  Looking further tomorrow night and the next few are really cold -2 to -3 and I would cover them for that will they be OK handling this snow ice tonight and cover them tomorrow and shake them down.  Many Thanks for any advise as last year we were lucky in are first gardening year with a wet mild winter. 

Cheers James



  • pansyfacepansyface PEAK DISTRICT DerbyshirePosts: 18,041

    Not sure what an H3 zone is. Are you in UK? What types of plants are we talking avout?image

    Apophthegm -  a big word for a small thought.
  • JamesOJamesO Posts: 230

    Hi I'm in Salford Manchester the rating is from the RHS should of just typed rating rather than zone.   H3 is +1 to -5 then H4 -5 to -10 and so on to H7


    here is a PDF print out

  • SalinoSalino Posts: 1,609

    ..I wonder what these plants are exactly...?  if you have them in a sheltered corner they should be alright.... I might fleece cover, depends what they are.... and I don't take too much notice of these hardiness zones... I have a plant in H2 that has survived the last 5 winters, down to -10c and covered in snow (I put old carpet around the base).... but it's sheltered from the worst freezing wind...which I think does the most damage...

    ..I've got several in so called H3 and I'm not worried about them at this will have to get really bad for me to take action with these...

  • JamesOJamesO Posts: 230

    Got agapanthus some Imperata cylindrica 'Rubra'  grasses, Alstroemeria                     

  • pansyfacepansyface PEAK DISTRICT DerbyshirePosts: 18,041

    Thanks for the info about the H3. Never heard of itimage

    Alstromeria here up in the peaks of the Peak District are as tough as old boots - easily minus 10 without problems.

    Apophthegm -  a big word for a small thought.
  • SalinoSalino Posts: 1,609

    ..the Agapanthus I would protect, especially if it's evergreen then I would fleece now,   or protect with bulky straw weighted down, around the plant... I think winter wet can do a lot of damage to these...

    ..the others I wouldn't worry too much...

  • Fishy65Fishy65 Posts: 2,253

    I think in general if its native to the UK then it will be fine. I've got seedlings outside on the garden table...ragged robin,water avens and primroses that have been there since October. They're all fine, some little delphiniums too image

  • ObelixxObelixx Vendée, Western FrancePosts: 24,250

    Snow acts as an insulator so don't remove it from hardy perennials but do shake if off any branches it is weighing down as the weight can permanently damage plants.

    The RHS has recently recognised that varying degrees of hardiness are needed to describe plants more accurately and found that the USA zoning system wouldn't work in the more moderate but also more variable over small distances UK climate.   I'm in central Belgium and find plants do better in winters with lots of snow than the ones where it is cold for long periods without any snow.   It can make the difference between surviving -25C and -15C.

    Imperatas, pennisetums and evergreen viburnums do not do well here.

    "We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
  • LynLyn DevonPosts: 17,013

    I always bring my pot grow Agapanthus into the unheated greenhouse for the winter.

    I never got to finish all my mulching though, still got dahlias not covered.

    Gardening on the wild, windy west side of Dartmoor. 

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