ROOT PRUNING
paula.conway
Posts: 121
in Plants
Hi everyone, does anyone know when the best time is to root prune box. I have quite a few in pots and containers and they are quite root bound. I need to encourage new growth from the centre of the box as they are quite bare.For the past week, I've been pruning all the old dead wood and leaves from inside my box topiaries. I pulled one out of its pot and there was hardly any soil in it and what bit did fall out ,was like fine sand. I cut quite a lot of roots off it and re potted in fresh compost. I've only done this to the one, because I'm not sure if its going to survive the trauma and die on me. I know the best time to move shrubs and trees is November to Feb when their dormant, but has anyone done this root pruning before?
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why prune the roots? Sounds like it just needs a bigger pot with some good quality soil based compost such as John innes no 3 and plenty of water. Perhaps you could stand the root ball in a bucket of water for a couple of hours before you pot it on and then water thoroughly again.
I agree. They need more food and compost, not less root. If their centres are bare they may have box blight in which case all the affected growth needs cutting out and then you should apply a foliar feed to help the rest of the plant recover and regrow.
The RHS has this advice - https://www.rhs.org.uk/advice/profile?pid=96
If you can't increase pot size then you need to decrease the size of the plants to reduce the demands on their resources of food and water and root space.
"We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
Hi Bright star and Obelixx, thanks for your replies.I need to prune the roots so I can keep them in the same size planters. I have had these box for quite a few years now and kept them more or less the same size and shape.I have watched this root pruning on YouTube but they don't tell you what time of year best to do it. They just prune the roots when pot bound. I have had a problem with spider mites and woolly aphids in the past. I have got box planted in the ground and they are growing new foliage in the middle, so I know there ok .I don't think they have box blight .If they've gone brown round the top of the pots, I know its because the cats have sprayed up them. I've seen them do it. You can see the evidence trickled down the pots as well. This is why I have a lot of them in pots and not in the ground. I have a large Buddha topiary in the ground and the cats have sprayed at the back of him. I cut away all the dead wood and put a large pot in the way to try and prevent them spraying in the same place. As for the root pruning, I didn't know wether it would be a good idea to do it now with the weather getting colder or wait until spring.
The most comprehensive information I can find is here
http://www.boxtrees.com/topiary.html
They suggest trimming roots when potting on. I would be potting on just before periods of growth e.g. March, so that's when I would root prune too - just my suggestion.
Thanks Dovefromabove, I have only done the one up to now, as it was looking under nourished being so pot bound.so I will see how this one does and wait until march time to attempt to do the others.