The Daily Telegraph - Saturday - Saturday
HELEN YEMM THORNY PROBLEMS
This week: how to get plumbago through the winter, dealing with an exotic visitor, and planting inspiration strikes afresh
TLC FOR A PLUMBAGO
How should I overwinter my pale blue plumbago? Last year it was small enough to overwinter in a porch. It spent this summer in a carport that gets morning sun. Now it has grown enormous and is very thirsty.
MARIE CAINE – VIA EMAIL FROM
CHESHIRE
How sheltered is your carport, I wonder? If it is tucked up against the house and stays more or less frostfree you can leave your plumbago (Plumbago auriculata, or Cape leadwort) where it is, protecting its roots in the pot with bubble wrap.
If we have a prolonged cold snap you will certainly lose most of the top growth, but if the roots remain unfrosted the plant should be able to shoot out from a few inches above soil-level (like a fuchsia). It will grow rapidly as the weather warms up, and will probably flower by July given encouragement in the form of regular doses of tomato food. Plumbago flowers on new growth anyway, so you would normally cut it back in spring to encourage more compact flowering growth.
Put your plant outside in a sunny spot from July to October: with more direct sun its growth will far be less leggy and it should flower better. From what you say about “thirst” it may need a larger pot in the spring as well. Remember to ease off on the watering in dormant months.
AN ALIEN HAS LANDED Gill Glover
has asked me to identify, via some fuzzy pictures, a curious interloper that turned up this summer behind her greenhouse. She also wonders where it came from. She missed its flowers, she says, but it is now producing alien-looking, plum-sized prickly seed pods.
This is undoubtedly thorn apple, Datura stramonium, a poisonous weed. Gill should pull it up, taking care not to let it graze her skin, and dispose of it straight away (not in her compost bin) before the pods ripen and cast small black seeds around the place. Rogue seeds of this plant are assumed to come from imported bird feeds (see reallywildbirdfood. co.uk for home-grown feeds).
While on the subject, I might mention other plants that similarly crop up in gardens, generally but not always in the vicinity of bird feeders. Hemp (a close relation of cannabis) turns up fairly often, as does American pokeweed (Phytolacca americana). This one is a tall and eye-catching plant, carrying at this time of year luscious-looking (but poisonous) clusters of wine-red seeds. As I understand it pokeweed is not quite in the same poison league as thorn apple, but if in doubt, as with all uninvited plants, it is best to treat them as one-off curios and not let them seed around.
SEND YOUR QUESTIONS
Write: Gardening, The Daily Telegraph,
111 Buckingham Palace Road,
London SW1W 0DT
Tweet: @TeleGardening
Email: helen.yemm@telegraph.co.uk
For more tips and advice from Helen Yemm, visit telegraph.co.uk/authors/helen-yemm Helen Yemm can answer questions only through this column.