Kim Wilde answers your gardening questions.
I have a climbing hydrangea on a north wall that is now five or six years old. Despite feeding, watering, manure - anything I could think of - it has never flowered. Any advice?
This deciduous climber ( Hydrangea anomala subsp petiolaris ) hails from China and the Himalayas, where it grows up trees, flowering near the top. The first time I saw them growing like this was in Beth Chatto's enchanting woodland garden in Colchester. These hydrangeas often take a few years to get going, and if yours is otherwise in good shape, I expect all you need is a little more patience. Good, rich soil is essential, which you're providing by feeding and manuring. I would suggest planting the vigorous climbing rose R. 'Madame Alfred Carrire', which freely produces white, blush-tinted double-blooms. This will tolerate your shady wall and put you out of your misery until old petiolaris bucks its ideas up.
Last year, I tried to propagate new plants from Calluna vulgaris cuttings, but with no success. Can you help?
Perhaps the simplest way to increase your stock of C. vulgaris (heather) is to use a propagation technique called 'dropping', though this involves losing the parent plant. Dig a hole the size of the entire plant, bar a 3cm tip, which will remain exposed above the soil surface. Dig the base of the hole well, incorporating grit and peat substitute if the soil is heavy and likely to become waterlogged.
Drop the plant into it and cover with a multipurpose compost and peat substitute. Add perlite to open up the mixture as there needs to be a reasonable amount of air around the roots. The exposed tip will send down roots where it touches the soil, giving you baby plants which can then be separated and replanted. The parent plant can later be dug up and discarded. 'Dropping' should be done in spring, though autumn is fine, too (heathers are pretty tough), and preferably in semi-shade, making sure to keep the plant moist. If 'dropping' in spring, the branches will have rooted fairly close to the soil surface by autumn.