Garden Guru

Q My evergreen agapanthus looks miserable after the recent cold. Will it recover? Bryan Collins

A Evergreen agapanthus are more tender than their deciduous cousins, so are best covered with fleece if frost is forecast. The leaves are likely to take the brunt during a cold snap, so cut back any dead foliage. Feed with a slow-release fertiliser and cross your fingers. Hopefully, the roots and crown will be fine, but only time will tell.

Q I’ve bought six Fargesia nitida ‘Pillar’ bamboos, which are described as ‘non invasive’. Is this right or do I need to take precautions so they won’t affect nearby buildings? James Ainge

A Over the past few years, a flurry of new fargesia bamboos have appeared in garden centres that are described as tight clump formers that won’t spread. Some nurseries suggest that ‘Pillar’ doesn’t require any special treatment, but if you’re worried, I would suggest installing some root barrier material.

Q The leaves of my choisya and olive are being stuck together by a grub that lives inside. What is it and how can it be controlled? Sue Foot

A This sounds like tortrix moth caterpillars. This pest attacks several shrubs in my garden. I can’t stop it completely but reduce its impact by inspecting plants daily, opening up folded leaves and squashing the bug.