This blog reviews the latest products, plants and innovations in gardening. It also provides a link for my many gardening friends who are members of the GardenMessenger and Seedmessenger Yahoo groups and their sub-groups that I moderate.

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Location: Australia

I am a semi-retired UK botanical garden curator and former international horticultural consultant, who has worked extensively in Europe, the Middle East, North America and Australia. I spend part of the year in Australia and part in Europe, mainly due to family and work commitments. I earn my living from writing and editing Internet copy, articles and books. I have written over fifty books on gardening and have been translated into twenty-four different languages. I am a former UK Garden Writer of the Year and a previous Quill & Trowel Award Winner from the Garden Writer’s Association of America. I am interested in developing gardening communities on the Internet and I manage the popular GardenMessenger Yahoo group, along with its various sub-groups like PondMessenger and SeedMessenger. I also edit International Water Gardener and its associated regional web-sites.

Sunday, May 07, 2006

Biological Control, Chelsea Show Garden, Rock Garden Construction

Wild flowers in nursery rows

We are all looking towards biologically friendly ways of controlling pests and diseases in our gardens, and I was delighted to learn recently that the Dutch nursery industry is too. The combination of economics, pressure from legislation, and public demand, has led to some serious experimental work taking place at a research station in Horst in southern Holland. Although directed at the nursery industry, much of what is being reported from the early results of this work is very useful to gardeners. Some of these results are to be expected, but I think the benefit of following the outcome of these trials is that researchers will quantify as far as possible the benefits. This always helps when it comes to promoting techniques that could all so easily be regarded as a little freaky by traditional mainstream gardeners. The following are some of the experiments that are being conducted and the early results that are being yielded.

The presence of natural predators of harmful insects are being encouraged by planting hedgerows around production blocks. Further encouragement is provided through flower planting in between the rows. Some twenty different flower species were tested for their attractiveness to predators. Blue-flowering plants such as Veronica and Centaurea turned out to be very attractive to hoverflies, which feed on aphids.Tagetes were grown prior to the planting of a crop of roses, to kill the nematodes or eelworms, that would otherwise damage their roots and slow their growth. Nesting boxes for great tits were hung in the fields, to encourage the birds to feed on caterpillars in the spring. It is well known that the tit family consume large quantities of caterpillars when feeding their young. From these simple introductions a great difference has been made to commercial production and adapting such simple techniques to domestic garden use should bring similar advantages.

Hoverflies love blue-flowered Veronica

Other experiments are continuing with the introduction of a native predatory mite against rust mites and spider mites in a field of Lindens or Tilia. A crop rotation is being used of hedging conifers, followed by roses, herbaceous perennials and young street trees. Growing the crops in this order has been shown to prevent problems with soil-borne diseases. Finally cover crops of white clover and rye have been sown around young trees. This goes against everything that we learn about young trees and root competition. However, providing that the trees are kept well watered to compensate for the competition from the cover crop, there were great benefits in controlling the leaching of nitrogen from the soil. As I get updates on all this work I will let you know.

Chelsea Show Gardens Preview
During each of the days running up to the Chelsea Flower Show I am previewing a show garden. Although these are often regarded as garden theatre and not as sustainable under normal gardening conditions, they are often full of interesting and innovative ideas which can be taken, at least in part, and used in our gardens at home.

The Halifax Garden - These Four Walls

This garden aims to show how a good garden design can create a garden that becomes a key room in the modern home. Stuart Perry, the garden designer, set out to design a fresh, inviting garden that contained the essence of the Scandinavian countryside. The garden aims to create a feeling of being immersed in a relaxing environment whilst still retaining the functionality of a modern garden. A unique feature in this garden is the 'Sove' summerhouse, which forms the rest zone of the garden. A hand-crafted bench from New Zealand sits at the far end of the garden near a glass waterfall. Stuart believes that the glass wall of this waterfall is the largest single piece of glass ever used in the UK and possibly Europe. It measures 2.4m (8ft) tall and 8m (26.5ft) wide and weights some 2,000kg (4,400lb).

Show rock gardens are uncommon

It is surprising how fashions in gardening have changed over the years. I have been involved with the Chelsea Flower Show from time to time and working with the set-up is exhausting. However, it is also exciting, especially the first time. That for me was in 1965 with a nursery called Perrys Hardy Plant Farm, Enfield, Middlesex. They specialised in hardy perennials and aquatics and were regularly awarded a gold medals for their Chelsea exhibits. The nursery no longer exists, but the legacy of their work remains in well known garden plants like Iris sibirica ‘Perry’s Blue’ and ‘Perrys Pigmy’, as well as Papaver orientale ‘Marcus Perry’. It was from this happy time that I recalled, while gathering the information for the Chelsea show gardens for this blog, how the gardens of that period seemed to be dominated by rock gardens. Nowadays they are thin on the ground at Chelsea, yet they have much to offer to gardeners, irrespective of the amount of space available. A rock garden need not be a full blown affair in order to enjoy growing alpine plants, a rocky outcrop can give enormous pleasure.

A rock garden or rock feature should be constructed in an open sunny and well-drained position in the garden. No matter what size or shape it takes a rock garden must embrace the principles of a moraine. It should not be a mound of soil with rocks placed indiscriminately on it, but a collection of free-draining debris mixed with a gritty soil that is distributed through and around a rocky structure. Such an arrangement provides the perfect conditions for growing a wide array of fascinating mountain-dwelling plants. There are a number of different stones that are readily available for rock garden construction. Sandstone, limestone, and granite are amongst the favourites, although most gardeners concede that a stone that is natural to the locality generally fits into the garden best of all. It is also less expensive because the transport costs have not been so great in getting it to the garden centre. While it is possible to gather rocks that occur naturally, make sure that any possible conservation issues have been checked first. There may appear to be plenty of rocks scattered around the countryside locally, but their removal may not always be prudent or legal.

A rock garden should grow out of the landscape

The rocks that are to form the base of the rock garden should first be selected and placed in position to create what almost amounts to a "retaining wall". This outlines the contours of the feature. As far as possible a rock garden should look as if it is growing out of the landscape rather than it is sitting on it. There are many gardens that are homes to heaps of soil with rocks awkwardly protruding from them. Such rock gardens are generally referred to by professionals as "currant buns", and are both visually unappealing and poor homes for most rock garden plants. In order to create a natural-looking rock garden select a rock to provide the focal point. This is generally one of the largest rocks and is known as the key stone. It exposes at least two faces, often more, and it is from this that the remainder of the rocky outcrop develops.

When placing rocks make sure that the strata runs in the same direction. If there are slight colour variations create sufficient space between the rocks to allow for liberal planting. Two rocks of slightly variable colour, which are separated by plant foliage, are no longer noticeably different. Once the basal stones of the rock garden have been laid the area between should be filled with a mixture of about two thirds of broken stone or brick and one-third gritty soil. Having laid the base, filled the cavities, and generally formed a solid plateau, further stones can be lifted into position and the process repeated until the formation is of the desired shape and height. When completed, pockets between rocks that are to provide homes for plants with specialised requirements can be excavated and suitable compost introduced.


New Rose ‘Osaka’
This is the new rose that has been launched to coincide with the 2006 World Rose Convention. It is a hybrid tea or bush rose with high-centred, slightly scented flowers, some 15cm (6ins) across, each with 46 or 47 petals.

Award Winning Carrot
One of the most remarkable All America Selection winners for 2006 is the F1 Carrot ‘Purple Haze’. It is particularly likely to find favour with those who enjoy cooking. 'Purple Haze' has a purple exterior and orange interior. Circles of cut roots have two distinct colours: a halo of purple with a bright orange centre making it ideal for salads. When cooked in water, the purple colour will fade. When carrots are cooked quickly, as in a stir-fry, the purple colour remains.


The World Rose Convention 2006
11th-17th May
Miyako Hotel,
Abeno Medix 12F,
Asahimachi 1-chome 2-7-1206-2,
Tel: +81 6 6772 8804
Fax: +81 6 6631 8741
Web-site: click here.

2006 National Spring Rose Show and Convention
17th,18th and 19th November
St.Mary’s Hall,
Contact: Mrs Lynley Neal
3 Ashford Grove
RD. 3, Blenheim,
New Zealand.
Tel: +64(03)5705275
Web-site click here.

Happy Gardening



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Nursery: PPH
Veronica: Wikipedia
Rock Gardens : Royal Horticultural Society
Carrot: All America Selections

If you have enjoyed this publication, you may also like to visit the monthy SeedMessenger gardeners’ seed saving and seed exchange blog click here.

and the weekly water gardening blog PondMessenger click here.

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