Kim Wilde answers your gardening questions.
I have a Euphorbia mellifera which grows healthily outside. Last year's stems are now about 1m tall - a little tired, but about to flower again. There are lots of fresh, small stems appearing at the base. Do I remove all the old ones now, or have I left it too late?
Stems should be cut after flowering, to encourage new growth at the base. The young shoots will then flower early next year. This species is only hardy in milder regions in well-drained soil against a warm west or south wall. Colder areas can still enjoy this deliciously honey-scented plant by growing it in a container and overwintering in a greenhouse. As I'm sure you are aware, euphorbias contain a sap that is toxic and irritates the skin, so do wear gloves.
I have lavender in a pot on my balcony. It is fresh and full of growth on one side, but bedraggled and dead on the other. Can I just cut off the dead-looking stems at the base?
When growing lavenders in containers, you have to pay extra attention to drainage, making sure you add plenty of grit to a soil-based compost. Your plant has obviously struggled through a damp, cold winter, but has hung on in there. Cutting out dead, damaged or diseased wood is always sound pruning advice, and a spring prune should rejuvenate your beleaguered plant. Maintenance includes removing flowering stalks after flowering, and pruning in spring to keep the plants compact and bushy, but avoid cutting back into old wood.
Can you advise me on the taming of phormiums? I have two, a Phormium tenax, and a 'Bronze Baby'. Both are now about 2m tall, and I would like them to stop there.
Phormium tenax can grow to 4.5m. Try digging the whole plant up and dividing it with a spade or knife. They can't really be restricted height-wise, but cutting one back to just below 1m might encourage new shoots to develop. If you're desperate, it is certainly worth a try.