Ness Botanic Gardens, Wirral
Duration: 43 minutes
First broadcast: Friday 20 September 2013
Peter Gibbs is joined by Matt Biggs, Bob Flowerdew, Anne Swithinbank and James Wong to answer questions from a local audience at Ness Botanic Gardens on the Wirral.

Produced by Victoria Shepherd
A Somethin' Else Production for BBC Radio 4.

This week's questions:

Q. Which plant would the panel have most liked to have introduced to the UK and which plants are they glad they didn't?

A. Blue rose (a variety of which has still has not been found and introduced), Rubus Macrocarpus (the 'Andean Giant blackberry' has only been photographed once, in the 1920s, and never been seen since) and the grape vine. Unwanted plants include Japanese knotweed, Leylandii, Poison Ivy and mini sweet corn.

Q. Can the panel offer any advice to a new student of horticulture?

A. Horticulture is taught with many exacting techniques, which can be quite daunting, but don't be daunted by the hard and fast rules. Conduct your own trials - ask questions and try it out on the ground!

Q. We planted what we thought were two cucumber plants - but they did not produce cucumbers. What did we grow?

A. This is probably a marrow! Let the seed merchant know if you purchased incorrectly labelled seeds.

Q. When growing sprouts, should the leaves be removed as the plant develops?

A. Around November, the rosette of leaves at the top of the plant should be nipped off, which ensures large sprouts in time for Christmas! However, the lower leaves should not be removed.

Q. What can the panel suggest for a very small back garden that only gets the sun in the early morning and a very small front garden in full sun, preferably providing year-round colour and a habitat for bees and butterflies.

A. Planting some controllable hedge plants in the front garden to provide privacy will make the space more usable - Yew, Hornbeams and Quince in tubs are all recommended. For insects, Borage is a favourite with bees and will also deter slugs thanks to its furry leaves.

Q. Which are the easiest edible fungi to grow?

A. Oyster mushrooms come in many varieties and colours - the easiest to grow are the white and grey forms. Sprinkle the spores at roughly 50 page intervals into a water-soaked telephone book, then place into a plastic bag and leave in a dark place. Once covered in white mould, make some holes through the book and place in a brighter location. The fruiting bodies, the mushrooms, will grow through the holes.

Q. In 2006 we planted 1500 deciduous trees on a two-acre plot. We have done very little weeding or maintenance on the grass beneath - are we doing the right thing?

A. In the first four years after planting, keep a one-meter diameter circle around the base of each tree free from grass and weeds. The trees will do much better in these conditions, without the competition from the weeds and grass. Either a residual herbicide or a mulch mat can be used to achieve this. Foxgloves, ferns and other shady-type plants can be added at a later stage (nine-10 years), after the number of planted trees has been thinned out.

Q. Can my Heleniums and Marguerites be split soon, as they have gone mad this year?

A. This autumn should be good for planting as there will be residual heat from the late, hot summer. Wait until the ground has moistened slightly before moving the plants and then lift, split and move the plants as soon as possible. Basal cutting can also be taken in the spring.

Q. My 'Bird of Paradise' plant has never flowered, despite producing leaves each year. The plant is about 3ft (1m) tall, in a 14in (35cm) pot, and is moved inside in winter.

A. These plants are hungry feeders, so the compost should be changed regularly and the plant watered very regularly. In spring, repot into a slightly larger pot with fresh compost. Once the plant has settled, after about a month, water with a general purpose liquid feed about once a week.

Q. When should topiary Yews be pruned and how vicious can the pruning be?

A. Yews can be pruned at any time of year - whenever there is time in one's gardening year - and can be taken back quite hard, until it is completely bare if necessary