Every week, Telegraph gardening expert Helen Yemm gives tips and advice on all your gardening problems whether at home or on the allotment. If you have a question, see below for how to contact her.
Go bananas in a sheltered corner
For two years Charlotte Weston has grown a banana in a large glazed pot in her “tropical corner”. The first year it grew well and spent the winter in a leaky unheated greenhouse. She cut off its ugly old leaves in spring and repotted it, moving it back outside in April. It expanded and grew taller.
Charlotte took a chance last year and, with difficulty, dragged the now-unwieldy pot to a sheltered spot under the canopy of a conifer where it “just managed to survive”, she says, but was slow to recover and its new stems only achieved half their previous height. Would it do better this winter in with its roots in the ground, she asks? And can she grow cannas in pots, she adds, or would they also do better in the ground?
“Maybe” is the answer to the first question. If her “tropical corner” is very sheltered, she could plant out the banana properly.
But to be really safe it would need to have all its leaves cut off carefully in late autumn every year. Its stems would need a protective fleece or hessian jacket before the frosts arrive and, in a colder garden, may only survive inside an additional straw-filled wire cage.
The alternative may be to drag the pot into a sheltered place again this year, double bubble-wrap the pot and de-leaf, wrap and straw-cage the stems (as before) as best she can, and keep her fingers crossed for a less-than- brutal winter.
Cannas planted in the ground may come back (but will flower rather late) only if well protected by a dry mulch (e.g. bracken or fern leaves pegged down under fleece). They might do better if lifted and dried off and (like dahlias) are “restarted” in spring.
New home, new tree?
I was given a winter flowering prunus five years ago as a birthday present. I am moving to a new house and would like to take it with me. Is that possible?
Martin Courtis – via email
Moving a five-year-old deciduous tree is difficult but not impossible, and should be done while it is dormant between November and early March (a tricky decision, perhaps, since this tree flowers intermittently during the winter). Do bear in mind that its roots are now likely to extend under its entire canopy, as well as downwards.
There are several factors to take into account: will you be able to manhandle the tree, with its wet and weighty root ball, out of the ground and on to something in which it can be wrapped and tied up securely (e.g. sacking, porous landscape fabric) to transfer to your new garden? Can you replant it before it comes into leaf?
It may have outgrown any support in its current site, but when newly vulnerable in its new position it should be secured with tree stakes while it beds in. Last, this tree is quite fussy – it dislikes waterlogging and clay soil. Will conditions in your new garden be suitable?
If I seem to be putting obstacles in your way… well maybe I am. It seems a shame to go through such a palaver and possibly risk a tree’s life for what are, after all, sentimental reasons. You could just plant a new one.
Mexican climate standoff
I bought a single seedling of cup and saucer vine and planted it at the base of my new pergola. At £1.25 for a single seedling it seemed a bit steep at the time, but it has been stunning, with beautiful foliage growing to cover half of the structure and producing large, dramatic, green/purple bell-like flowers. Will it survive the winter if I give it some protection?
Lisa Kember – via email
Probably not. This Mexican native (Cobaea scandens), is a perennial sold here as an annual, as it needs a warmer climate to grow on a second year and beyond. That said, a cobaea planted against a warm, south-westerly-facing wall in London surprised me by dying back in a mild winter and reviving (rather weakly) in spring. But it was not nearly as impressive as before, and soon faded.
Fellow “perennial” Mexican, rhodochiton (please note, Steve Sharp, who had a similar query), is also unlikely to weather our winter successfully. However, both are easy to propagate from seed. Inspect your plant: it may well have made some fat pods packed with seed that you can dry off slowly and use next year.
Timing is the secret to growing such a vigorous, tender climber from seed. Don’t even think about starting the seeds off (in a greenhouse or on a bright windowsill) until mid-May: after germination, growth will be super-rapid and to avoid hiccups, the move to a suitable site (or pot) outdoors must be timed to coincide with warmer night temperatures.