Please help! How to/can we rescue bamboo
 

Hi everyone,

Here's our tale of joy and woe:

We have a 3 bamboo plants growing in pots on our glass paneled, north-west facing, 2nd floor balcony. We've had them about 2-3 years. I can't quite remember what type they are but they are clump-forming about 1 meter tall and quite bushy at the top, with bright green leaves and yellow stems.

We repotted them into bigger planters (troughs, 30cm wide by 35cm deep) spring before last (2008) and they absolutely thrived, so lush, bushy and bright green. When we repotted them we incorporated controlled release fertiliser pellets and water retaining gel in the compost.

This year however the leaves started going brown and black and there are only very few green leaves. We had a massive infestation of greenfly on all three in the spring but this was sorted with the introduction of ladybird larvae. I'm aware that they refresh their leaves but there does seem to be a massive amount of leaf drop.

The pots are free draining and they have been watered to be damp but not wet. Here in Manchester we have had a few 'BBQ summer' days but nothing Saharan.

Having looked at various posts here and elsewhere we think we've done everything right upto now but are now unsure what to do next.

Any ideas what could be wrong? And any advice on what we can do now to improve the situation if we can?

We don't want to admit that they maybe dying and there is nothing we can do!

Many thanks in advance for your help.
J&D

Looks like you have everything right to me. Even the selection of variety for pot culture seems sensible. The main problems with pot-cultured bamboo are over- and under-watering. The latter can be due to the pot becoming so full of roots that there is no space left for soil/water, but you repotted to a larger pot recently so that shouldn't be a problem yet.

Greenfly are only an occasional pest of bamboo, the greefly usually have juicier pickings. So the heavy greenfly infestation may be an indication that the plant was already weakened. I wonder if some vine weevil grubs have been chewing the roots, or some other root ailment. Or if the greenfly brought in some rare virus.

The only other thought is that bamboos don't like strong winds. This kind of bamboo naturally grows in the understorey of forests, where it isn't very windy. I wonder if your balcony, although glass panelled, is some kind of very windy place.

I'm not sure if the culms are dead or merely defoliated. If the culms are dead, the plant might resprout from the roots next year. When the weather is Septemberish, tip one out of the pot and have a good look at the roots.

Many thanks for your super quick reply!

Some interesting thoughts. The wind could be an issue. We have an Acer on the terrace by our front door and in previous years (like the bamboo) it has thrived. Except this year it is in a sorry state, wind burn seems to be the diagnosis, a possibles cause for the bamboo's ill health.

We have had a fair few vine weevils on the terrace but haven't noticed any on the balcony. Bu then don't spend much time out there as the bamboo looks so sorry! Will wait until the weather is 'Septemberish' to investigate that avenue.

I guess we should prune down the nearly dead/dead culms in the winter to encourage any new growth?

Any further thoughts on that and previous problem much appreciated.
J&D