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.

Q My Clematis montana is romping over the garage, covered in flowers, but the bottom half is bare. Should I cut it back hard after flowering in the hope that it will grow again from the base next year? – Isabel Mcleod, Gatehouse of Fleet. A Yes, wait until the flowers are over then cut the whole thing back to about 24cm from the soil. New stems will appear.

Lupins are short-lived, so take basal cuttings now or grow more from seed to ensure that you have fresh, young plants. Q What is the best mix of seed, soil and sand to top-dress a sandy lawn? – Ian Rae, by email.

A As your soil is already sandy, I wouldn’t add any of this to the mix. Instead aerate the lawn then spread a mix of equal parts topsoil and compost over the grass. This will help to improve the soil and add some nutrients. If peonies have failed to flower, cut back plants shading them and ensure the roots have not been buried under mulch. Q Brown leaves and scorched tips have appeared on my large phormiums. Can I cut these off? – Eileen Chalmers, Pitlochry.

A Yes. Using a pair of sharp scissors, cut off dead leaves as close to the base as possible and trim tips at a sharp angle.

Instead of digging out thistles, try removing the top growth whenever it appears. This should weaken the roots. Q I’ve got a ligularia that produces a few leaves then dies down again. What’s wrong with it? – Mark Barr, Linlithgow.

A Ligularias are marginal plants. They like damp soil that doesn’t dry out. I suspect yours is going short of moisture. If you don’t want to move it, then you will have to water and mulch it regularly to get it growing strongly.

Grow marigolds among your greenhouse tomatoes to help ward off insects. Aphids and greenfly are repelled by the smell. Q Can you tell me how to get rid of the mare’s tail that’s invaded my veg patch? – Holly Wilson, by email.

A You probably don’t want to use weedkiller near your veg, so you are going to have to tackle this by hoeing off the shoots below soil level. Keep doing this until its time to dig over the soil in the autumn, when you should remove every trace of root. Next year try growing your crops through black polythene as this should help to suppress the weed. Dark vegetables have more nutrients so grow red lettuce, such as ‘Relic’ to help boost the goodness in your salads.