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Advice on care for certain perennials please

Can you offer advise on which perennials benefit from being cut back and others left please?

1. Agastache blue fortune.  Cut back or leave? This has really sprawled and I think I should dig it up and move it to a place where i can stake it properly.  Also does it benefit from chelsea chop to help it stand better?

2. Savlia caradonna.  Looks pretty good and is still standing nicely with the seed things on - think I should leave well alone and just cut back to ground in spring?

3. Lychnis coronaria - Again really tall and has sprawled everywhere..leave or cut back? how far to cut back?

4. Monarda - about 18 inches tall and standing quite nicely with seed heads.  Again leave and cut back in spring? how far to cut them back please?

Many thanks

Posts

  • raisingirlraisingirl East Devon, on the Edge of Exmoor.Posts: 6,333

    Not a specific answer but in general - if the seed heads are attractive leave it. It helps wildlife, especially birds and protects the 'crown' of the plant from frost. The only reason not to is if the plants are tall and flopping around in the wind - if the old flower heads are heavy when they get wet, for example - as this can rock the roots and let water and then ice into the root ball. If they look awful, then cut back and consider mulching to protect the crown instead. 

    With the agastache, if you want to move it, cut it back quite hard and shift it now and it will have time to establish it's roots before the weather turns really cold. If you move it in spring, and we have another dry spring, you'll need to water it, so I prefer to move things in the autumn, whenever possible.

    I don't know on the Chelsea Chop question, but the best thing would be to chop half the plant and see 

    “Light thinks it travels faster than anything but it is wrong. No matter how fast light travels, it finds the darkness has always got there first” 
  • Thank you so much for your answer raisingirl, Very helpful.  Would I then more or less just cut them all back almost to the ground next March or are there a couple there that don't like being cut that far back?

  • FairygirlFairygirl west central ScotlandPosts: 49,160

    Hi Copperdog - I don't currently grow any of those, but I tend to leave most perennials until they've died back and then just remove the dead foliage. 

    Anything 'sprawly' as you say, can be tidied up. I would just take the limp stems back to a decent leaf joint, and you may get a bit of new growth. If that means cutting to about six inches, it's certainly unlikely to do any harm. The salvia might benefit from a trim as well, but if it stil looks good, and the seedheads are fine, you could leave that until it looks rough. Birds will pick of any seeds that they fancy too. 

    If you get sufficient growth on the Agastaches to cut back in late May, I think that would benefit it. Some people do a 'half and half approach. Cutting back the front of the plant for instance, so that the back flowers first, and then you get the front later, which then helps to hide any duff looking stuff at the back! 

    Sometimes it comes down to aesthetics. A whole bed/border of dying perennials could look dreadful, but if there are evergreens or other shrubs/plants nearby looking good, they can hide the poor looking foliage. image

    It's a place where beautiful isn't enough of a word....


  • FairygirlFairygirl west central ScotlandPosts: 49,160

    Snap r'girl - think we're saying much the same thing!

    I missed the bit about moving the agastache, but yes - move according to your own conditions.

    I also tend to move things now because spring ground is usually very wet and cold here, but it depends on the plant. It sometimes means cutting back a plant that's still flowering if doing it now, so it's about compromise. 

    It's a place where beautiful isn't enough of a word....


  • Thanks too fairy girl.  I have lots of cottage type perennials in the front garden altogether so it does tend to look rather messy out there.  I need to stop buying so much in the way of perennials and get a few more shrubs going for more structure I think.  Thanks both for your replies.  

    I have 3 catmint walkers low out the front which I plan on moving as I keep getting all the neighbours cats in rolling on it! image I can see it has dropped loads of seeds under the plant already.  guessing  Ill have lots of new catmints out there even if I move it?

  • raisingirlraisingirl East Devon, on the Edge of Exmoor.Posts: 6,333
    Copperdog says:

    Would I then more or less just cut them all back almost to the ground next March or are there a couple there that don't like being cut that far back?

    See original post

    I usually pootle around all the beds once the weather starts to improve - usually about March - weeding, mulching and tidying up. I would take a view at that point by looking closely at how the new growth (if there is some) is appearing. If it's shooting from the base, cut back all the old growth to the ground. If it's shooting up the stems cut back to just above a new shoot, which could be high or low to suit how tall you want the plant to be in it's place. If there's no sign of life, leave it alone until there is.

    As you can see, my approach to gardening is a trifle ad hoc - there are others around who know the 'right' way to do things who may be along shortly to tell me where I'm going wrong image

    ETA - catmint doesn't self seed in my garden but that may be my soil and conditions don't suit it

    Last edited: 28 September 2017 12:54:19

    “Light thinks it travels faster than anything but it is wrong. No matter how fast light travels, it finds the darkness has always got there first” 
  • Thanks raisingirl.  Think that's where I could be going wrong! When I don't see any new growth early spring I dug stuff out thinking its dead! image  More patience is def required.  Have a good weekend.

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