A bonzai book (or www) might give you some ideas on root pruning and branch shaping.
I have a rhododendron that has been in the same pot for some 40 years with little disturbance. I feed it with GP soluble fertiliser about 3 out of 4 waters. Of course rhodos are not Pieris.
I also have two mophead bay trees planted in rounded pots. I repot them every year otherwise I wouldn't be able to get them out. I take few roots offf every time. The compost is John Innes, but I fill the sides with GP peat-free. Again, I feed during the growing season.
location: Surrey Hills, England, ex-woodland acidic sand. "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
Apologies for bobbing in, but if I may ask @Pete.8 Is there a preferred time of year to do this method (root pruning) as I have a Pieris that needs attention also. Many thanks.
Apologies for bobbing in, but if I may ask @Pete.8 Is there a preferred time of year to do this method (root pruning) as I have a Pieris that needs attention also. Many thanks.
The best time is when the plant is growing, then the roots will heal fast and start regrowing. So Spring through to early summer would be the best time.
Billericay - Essex
Knowledge is knowing that a tomato is a fruit. Wisdom is not putting it in a fruit salad.
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I have a rhododendron that has been in the same pot for some 40 years with little disturbance. I feed it with GP soluble fertiliser about 3 out of 4 waters. Of course rhodos are not Pieris.
I also have two mophead bay trees planted in rounded pots. I repot them every year otherwise I wouldn't be able to get them out. I take few roots offf every time. The compost is John Innes, but I fill the sides with GP peat-free. Again, I feed during the growing season.
"Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
So Spring through to early summer would be the best time.
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.