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Correspondence Edition: Barbican

Peter Gibbs hosts a correspondence edition from the Barbican Centre in London.

Peter Gibbs hosts a correspondence edition from The Barbican Centre in London. Matthew Pottage, Anne Swithinbank and Pippa Greenwood answer the questions from the GQT in box.

The panellists discuss getting a Loquat to flower, solutions for an ailing Yucca, and keeping houseplants alive when you're not going to be home for two weeks. They also offer advice on a straggly-looking cactus, recommend carnivorous plants for an unheated greenhouse, and suggest uses for used potting compost.

While answering the questions, the panellists are shown around the beautiful indoor gardens at The Barbican by Head Gardener Marta Lowcewicz.

Produced by Dan Cocker
Assistant Producer: Hester Cant

A Somethin' Else production for BBC Radio 4

Available now

42 minutes

Last on

Sun 27 Jan 2019 14:00

Fact Sheet

Q - I am wondering who else has a flowering Loquat? Mine has been in the ground for about 14 years; before that in a pot for 5-10 years. It has never shown signs of flowering before - it must have been the boiling hot summer. How do I make sure it flowers again?


Marta – We’ve got one at the Barbican which is 20 years old and we prune it every two to three years to ensure flowering and fruiting.


Anne – Use a high potash fertiliser and pray for hot weather


Matthew – We have one at Wisley in our Mediterranean garden and we keep it facing due south


Q - I have a Yucca plant in my bathroom. The smaller of the two that share a pot is doing well but the taller yucca’s leaves are turning yellowy brown and dying or going very dry. I water sparingly and mist now and then. Help!


Pippa – I worry that it’s lacking light


Anne – It might need its own pot in order to thrive


Marta – Get it some natural light


Q - My money plant (Crassula ovata) is at least fifteen years old (probably a lot more) and has flowered for the first time this year. I have read that they rarely flower. Can you tell me how long the flowers will last and if, or when, it will flower again?


Anne – The flowers can last for two or three months


Matthew – In a cool conservatory they will do well


Anne – They like a bright summer and a cooler winter


Matthew – The older plants flower more reliably


Q - I study at university and am about to go home for a break. This term I’ve collected quite a vast number of house plants. Can you recommend a cheap and cheerful way to keep my plants watered whilst I’m away?

I have a Ficcus Ali, a large Palm, Swiss cheese plant, Hawaiian palm, Indian rubber plant, x2 Calathea, a very large Alocasia, x 3 Fern, and 2 other tropical plants I haven't identified


Pippa – Wet capillary matting, stick one end in the compost and then the other end into a water reservoir and it will keep them moist


Marta – Give them a thorough water before you go and they should be ok for at least a week.  You could soak the terracotta pots thorough before you go.  An upturned water bottle can work in a similar way to the capillary matting too.



Q - I have several columnar cacti inherited from my mother-in-law and they are thriving in our new conservatory; growing taller. However, they are not 'filling out' at the base i.e. the radius of the top is greater than at the bottom. I could blame my mother-in-law for years of neglect, but that's a dangerous area. Is there a way I can encourage the bottom of the column to bulk out? I fear they may become top heavy. 


Marta – They do tend to get top heavy when neglected.  There is no way to encourage the bottom to grow.  You could cut the top off, dry it and propagate it.  Or cut it back and see if the bottom will attempt to grow again.


Q - I have this beautiful orchid with alternating white & pink flowers. The white flowers are fine but the pinks are dropping off! It’s the strangest thing I’ve seen! Any ideas? I have 20 phalaenopsis, all healthy, but this cymbidium doesn’t like me!


Anne – It sounds like two cymbidiums pushed together.  In spring take the whole plant out, divide them, and replant separately. 


Q - Please can you recommend a carnivorous plant to grow in an unheated greenhouse and some care tips?


Marta – The Pitcher Plants (Nepenthese) might be ok.  Generally they need lots of water; they do well on the edge of water features.


Matthew – General tips: stand them in a saucer of rainwater, accepting that they look tatty in winter, give them as much light as possible, don’t start with a Venus Fly Trap (start with something easier!).


Pippa – Some of the ‘Sundews’ (Drosera) would be good. 


Q - What to do with used potting compost? I cannot continually dump it in the flower beds without affecting the composition of the soil there, the depth of the plants and the level of the beds. How best to detox it and enhance it for reuse? 


Pippa – Compost does deteriorate after a while.  Check regularly for vine weevil grubs; you don’t want to spread them around. 


Anne – I bag it up and use it for bulbs – they don’t need particularly good compost.  If you’re storing Dahlia tubers it’s useful.  And it’s good for forcing things like chicory.  If you’re growing vegetables in containers you can use old compost for about a third of your bulk. 


Q - What’s the best way to overwinter a young banana plant (Musa basjoo) growing in a pot? I live in South Dorset.

Anne – I lift mine out, pot it, and put it in the greenhouse.  You can build shelters over them.


Matthew – They are very hardy at the roots you need to protect the top.  We wrap them in straw.  Don’t use plastic as it needs air flow.


Anne – give it a good water in autumn and then only water it a couple of times during mild spells in the winter. 


Q - Are there any houseplants that will thrive in a hallway which is dark enough to need artificial light to read anything?


Marta – If there is some natural light then try Aspidistra.  Maybe semiculcus succulent.


Matthew – Aglaonema is good.  ‘Mother-in-Law’s Tongue’ (Sansevieria trifasciata) is fine in deep shade.  Fittonia is good for a small space


Anne – If it’s a big space try the ‘Devil’s Ivy’ (Epipremnum aureum). Begonia lucerna actually would work but wouldn’t flower.


Pippa – Look into replacing the artificial lights with LEDs


Q - Can you recommend plants for a garden office? It is only heated when occupied and, during winter, freezing cold when not. I bought some houseplants and I think they’ve frozen to death. Many thanks.


Marta – You need to gradually adjust plants to new temperatures, don’t shock them


Anne – Wrap them in fleece


Matthew – Agave parryi or a tree fern or Trachycarpus palm would be all be fine.  Cycas revoluta and Clivias can both take a bit of cold.  Don’t overwater and keep them dry over winter.


Q - About six years ago we paid good money to plant a thong of horseradish on our allotment.  For the last five and a half years we have regretted it. Indeed for most of the last five years we have tried to remove, eradicate or kill it - all to no effect. What can we do?


Pippa – It’s extremely difficult!  Move to a new allotment!




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