Monday, April 27, 2009

Gardeners Question Time

Sunday 26.4.09

BBC Radio 4, GQT: Programme broadcast from 'The Potting Shed.'

Today the panel of expert gardeners were in the potting shed answering questions about the following plant related questions.


Ailing box hedge, the top of the plants leaves are going brown. Box blight was ruled out due to the following possible causes of plant damage. There is a path of concrete slabs beside the plants; water leaching from materials in the slabs could damage plant roots. Also path weed killer which is harsh and long lasting might have been used on the broadleaved weeds in the lawn and on the path itself; the residue from this persistent herbicide would cause damage to the plant roots, hence the uppermost plant leaves turning brown. Another reason could be soil compaction near the paving slabs which would constrict plant roots resulting in poor root development out into the soil and reduced ability of roots to absorb water and minerals from the soil.


What type of plants could be grown near the base of a domestic house furnace vent? Realize that this vent will be emitting heat and gas vapours which could damage plant foliage so care should be exercised when choosing and planting suitable plants. Phlomis fructicosa, Cytisus and Lavender are all Mediterranean plants that like sun and heat which could be grown in this situation. These plants are low-growing, but should be trimmed occasionally to prevent them blocking the furnace vent.


’More is less’ is an old gardening maxim that still applies today when planting a mixture of plants.


Alan Titchmarsh has a new soft back book about garden design (2009) which is available at Eason Bookstores nation wide. It can also be purchased online at www.amazon.co.uk and www.booksunlimited.ie


Yucca which has over the years grown to be a large tree reaching up to the height of upper window of a two storey house. What should be done to remove the tree which is blocking light entering the windows? The panel were of the opinion that this overgrown tree was in fact a Cordyline as it would be rare for a yucca to reach such a height. Note that the flowers of cordyline are very attractive to pollinating insects which is a good thing. Yucca produces knobbly roots which can be cut off and potted up. After about two years these roots will produce new plants. In the case of Cordyline, the tree can be cut right back to ground level which will ensure that it re-grows. Obviously it will take several years before it reaches the height of a two storey house. If the tree must be totally removed then it is best to employ the services of a qualified tree surgeon who will safely remove the tree and its roots.


Can asparagus be grown in containers? Container grown asparagus will not produce much of a crop due to the small amount of root space. A better planting option would be raised beds which will retain a certain amount of moisture and the plant roots can spread out into the soil. In a field in England asparagus roots have been found growing up to thirty feet in either direction of the main plant. The reason for this is that asparagus plants need room for their roots to spread allowing absorption of water and nutrients which are required to generate energy to produce numerous asparagus tips. Bob Flowerdew recommended ‘Gjnail’ which is a good Dutch variety of Asparagus.


The following plant topics were also discussed:

  • Pampas Grass which has stopped producing its fluffy white flowers
  • Pyracantha scab – what treatment is necessary?
  • Supermarket herbs are forced and will not re-grow
  • Sow vegetables from seed now! Full moon means that growth of seed will be extra good – Bob Flowerdew
  • http://www.wateronceaweek.blogspot.com/ an interesting Canadian gardening blog
  • A very helpful site all about growing vegetables for the your family:
  • http://www.vegetable-garden-guide.com/planting-asparagus.html


I will expand these points in the next blog post. Until then enjoy your garden even if it’s a humble window box or just two or three plant containers. Remember the old gardening maxim “More is less”.

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