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Pot bound roses - root pruning

TopbirdTopbird Mid SuffolkPosts: 7,587
edited 19 January in Tools and techniques

Hi everyone - but with a special call out to our rose guru @Marlorena....

I have offered to help a friend who has 2 small shrub roses (I think they're 4 - 5 yr old DA's but labels are long since lost) in terracotta pots which are a bit too small for them. However, the pots were expensive and she won't change them.

The roses were repotted very badly by her non-gardening son-in-law about 3 years ago leaving the graft union 2-3" above the level of the soil and the top 1-2" of roots completely exposed. Apparently there is a large root mass which is why the plants sit so high in the pot.

Can I do some severe root pruning on these roses and which roots can I tackle? 

Is it OK to cut the tap root if that's too long? By how much?

I understand it might be ok to cut some of the side anchor roots. Can they be reduced by about half if necessary?

And what about the fibrous feeders? Can I just trim those to fit in the pot?

I was going to reduce the top growth of the roses by between a third and a half depending how much I need to trim the roots. Is this the right thing to do?

They are currently potted in pure MPC but I was planning to repot using a mix of one third MPC and two thirds John Innes No 3. Does that sound right? 

I will water them in now and was going to suggest a regular feeding routine starting in March. 'Proper' rose food for the first feed then liquid seaweed once a month after that. Any views?

TBH - if these were my roses I'd just get on and do it but they're not. She's quite emotional about these plants and is putting all her trust in me to sort them out. It feels like quite a responsibility! 

I'd really appreciate your inputs regarding my plans and whether there's a better way to go about things. 

Heaven is ... sitting in the garden with a G&T and a cat while watching the sun go down

Posts

  • Busy-LizzieBusy-Lizzie Posts: 20,439
    I gave about 8 roses to my daughter when I moved house, 2 years ago. It was early winter when I dug them all out of their pots, which was quite a job as they were in very big pots and the roses were 5 - 8 years old, including climbers. They had been planted in a mixture of MPC, garden soil and rotted manure. Just MPC isn't enough for a rose. Pots should be about 60cms deep, unless they are small patio roses.

    I had to make them manageable to deal with and to fit them into the car. I trimmed all the roots and pruned the climbers down to about 3ft and the others to about 12" - 18".

    My daughter has planted them in the ground and they have all survived. The Malvern Hills and The Pilgrim haven't yet reached the height they were but I expect they will this summer.
    Dordogne and Norfolk
  • MarlorenaMarlorena East AngliaPosts: 7,129
    Topbird said:

    Hi everyone - but with a special call out to our rose guru @Marlorena....

    Hello !, thanks for the call out.  I'll answer you by quote if that's ok..

    I have offered to help a friend who has 2 small shrub roses (I think they're 4 - 5 yr old DA's but labels are long since lost) in terracotta pots which are a bit too small for them. However, the pots were expensive and she won't change them.

    The roses were repotted very badly by her non-gardening son-in-law about 3 years ago leaving the graft union 2-3" above the level of the soil and the top 1-2" of roots completely exposed. Apparently there is a large root mass which is why the plants sit so high in the pot.

    Can I do some severe root pruning on these roses and which roots can I tackle? 

    Yes, no problem, and no fret.. this is all very easy and satisfactory to do..

    Is it OK to cut the tap root if that's too long? By how much?

    Yes, see photos below.. You can make quite severe cuts if needed..

    I understand it might be ok to cut some of the side anchor roots. Can they be reduced by about half if necessary?

    Yes, absolutely..

    And what about the fibrous feeders? Can I just trim those to fit in the pot?

    Yes you can, but try to leave on as much as convenient to fit.. feeder roots are quite important so the aim is to keep as much of these as possible..

    I was going to reduce the top growth of the roses by between a third and a half depending how much I need to trim the roots. Is this the right thing to do?

    With the type of roses you have, yes, by at least half, and if were mine, I would actually cut them down to about 1 foot..

    They are currently potted in pure MPC but I was planning to repot using a mix of one third MPC and two thirds John Innes No 3. Does that sound right? 

    Yes perfectly ok, or if you can manage, the usual mix is 50/50, which provides better drainage..

    I will water them in now and was going to suggest a regular feeding routine starting in March. 'Proper' rose food for the first feed then liquid seaweed once a month after that. Any views?

    Yes, but if you can swop the liquid feed for Tomorite, I have found it gives excellent results.. always use non-organic for pots, organics are a waste for potted roses.. seaweed is great too, if you only want to use this, that's ok, Tomorite is better..

    TBH - if these were my roses I'd just get on and do it but they're not. She's quite emotional about these plants and is putting all her trust in me to sort them out. It feels like quite a responsibility! 

    This is not a problem at all, and she should be informed not to worry, this is usual practice and does not harm the roses.  Tell her it rejuvenates them, it may make her feel a whole lot better..

    I'd really appreciate your inputs regarding my plans and whether there's a better way to go about things. 

    Photos to follow to show you the way forward..


  • MarlorenaMarlorena East AngliaPosts: 7,129
    This rose is a hybrid tea, so not an Austin, and not as congested as those you are dealing with, but the work involved is the same..  The rose below took about 15 minutes of my time, it will be a bit longer for you as your roses are older..

    Removed root ball from pot..

    Scrape away as much of old compost as you can.. reduce top growth, in this case down to 4 inches as it's a hybrid tea rose..

    Root prune, you can see the cuts.. trying to keep feeder roots as much as possible.. you can root prune more than this if need be.  Cut all the thick roots..  I could have cut these back half as much again and it would be ok, but this was suitable for my pot..

    Place back in pot, and fill with compost mix.. making sure graft union is just below soil surface..

    Later that summer.. - all is well..


    You can be quite ruthless with roses.  Have no fear.. 

    best of luck.. 
  • TopbirdTopbird Mid SuffolkPosts: 7,587
    Thank you for the reassurance @Busy-Lizzie. Hopefully it won't be too long before your daughter's roses are back to their full height and glory.

    @Marlorena - what can I say? You're a real star. Thank you so much for the detailed advice and reassuring photos. Good to know my instincts were on the right lines but thank you for the 50:50 mix and Tomorite tips.

    I have always been quite tough with my own roses when the situation has demanded it (fence repairs and the like) and it's never done them any harm. I, therefore, gaily tell people that roses are as tough as old boots etc etc but it's slightly more daunting when faced with undertaking what will (almost certainly) be quite brutal surgery on someone else's beloved plants. I know that I'm going to have to send her inside to make tea when it comes to doing the cuts or she may faint🤣

    Interesting that it seems to be slightly more important to retain more of the finer feeder roots rather than the big chunky ones. 

    Thank you both again.
    Heaven is ... sitting in the garden with a G&T and a cat while watching the sun go down
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