Potting Shed

Welcome to my potting shed! This is the column where I’ll share all my gardening hints and tips – and I’ll try to answer any queries you may have.

I have a beautiful skimmia that I’d like to propagate. When is the best time to take cuttings? – Len Taylor, by email

Take semi-ripe cuttings in late summer, slicing through each stem just below a leaf to produce a cutting that’s 15cm in length. Dip in hormone rooting powder, insert around the rim of a small pot, and cover with a plastic bag until rooted.

My basil seedlings have gone mouldy. What did I do wrong? – Linda Morrison, Paisley

Too much moisture and not enough air causes “damping off”, which is what has happened here. Next time try not to overwater and remove any plastic cover as soon as the seedlings appear.

I’ve spotted a patch of Japanese knotweed in the field behind my house. Will the seeds travel to my garden? – Ian Donaldson, by email

Japanese knotweed doesn’t produce seed in the UK but it can invade gardens by underground rhizomes. Special polythene membranes are available that can be buried around boundaries to prevent the spread of this invader.

Part of my Leylandii hedge has turned brown. If I cut it back, will it regrow? – Mrs S. Bruce, Stonehaven

Root disease, insect damage and bad weather can all cause brown patches to appear and cutting back won’t help. You could try tying in healthy shoots to fill the gap but if the problem is extensive you may have to replace the hedge.

Why do dandelions pop up, unscathed, just hours after the grass has been cut? – Stephen Clark, Hamilton

This is one of gardening’s unsolved mysteries, which is why it is better to dig out dandelions at the roots than to attempt to mow them into submission.