Beautiful Buddlejas

Clumber Park, Walled Garden picture of Chris Margrave.
Clumber Park, Walled Garden picture of Chris Margrave.

Buddlejas are in full flower now, producing their maroon, mauve, blue or white blooms on long arching stems and attracting a host of butterflies to our gardens, hence their common name of ‘butterfly bush.’

Varieties of Buddleja davidii are easy to grow, preferring a well-drained soil and a sunny spot. Although they are perfectly hardy and will come through the winter undamaged, they are best planted away from frost pockets, as their young, emerging spring shoots can suffer from frost damage. f you buy container grown plants for planting now, ensure that they are regularly watered if the dry sunny weather continues.

The choice of varieties is huge. Fortunately buddlejas have recently been trialled to assess their attractiveness to butterflies and their value as garden plants. The former was done by the organisation Butterfly Conservation. In 2011 they found that the varieties ‘Foxtail’ and ‘Orchid Beauty’ attracted most butterflies, whereas last year the top two were ‘Dartmoor’ and ‘Autumn Beauty.’ Amount of scent and flower colour didn’t appear to be the determining factors, as varieties with moderate scent and mauve, blue and maroon flowers all scored high.

Between 2008 and 2010, the Royal Horticultural Society carried out a trial on the garden performance of over 100 varieties of butterfly bush, looking for the quantity and quality of flowers, hardiness and the shape and habit of growth of each variety. The best performers included the whites ‘Nanho White’ and ‘Darent Valley’, pale violet blue ‘West Hill’ and a compact growing purple variety ‘Camberwell Beauty’, which only grew to a height of 90cm/3ft, making it a good choice for smaller gardens. Most others will grow to around 2metres/6ft 6ins. The most popular variety with garden visitors, which also performed well in the trial, was ‘Miss Ruby’, described as having a flower colour nearest to a true red. Full details of the buddleja trial can be found at www.rhs.org.uk.

Varieties of Buddleja davidii are best pruned three times a year. Dead heading, that is removing faded flowers in the summer, can be classed as pruning. This will encourage the side shoots and their flowers to develop, giving a longer and fuller display. In October, after they have finished flowering, cut back stems by about half; this will help reduce damage caused to the plant by the wind over the winter. In March prune stems just above a bud to about 7.5cm/3ins from the older, thicker stems. This pruning will produce strong, vigorous stems topped with large flower clusters.

In the garden, buddlejas associate well with summer flowering perennials such as crocosmias, dahlias and lilies. To provide interest in the spring, when they consist of short, bare stems, plant spring flowering bulbs such as scilla and chionodoxa around them.

Jobs for the Month

Sow Japanese onion varieties such as ‘Senshyu Yellow’ and ‘Senshyu Semi-globe.’ These will over winter and help fill the “onion gap”, cropping in late June or early July, usually after the onions in store have been used up, but before the main crop onions sown in the spring, are ready.

Keep dead-heading, that is, removing faded flowers, to encourage plants to produce more blooms. Sweet peas and dahlias respond very well to this, as do plants in hanging baskets and containers.

Summer prune apple and pear trees grown as restricted trained forms such as cordons (on a single stem) and espaliers (with branches trained on the horizontal). Wisteria can also be pruned, shortening the long, thin shoots produced since March to about 15cm/6ins. Prune just above a bud.

Trim beech, yew and Leyland cypress hedges.

This is a good month to visit gardens, especially those which have herbaceous borders, summer bedding displays or kitchen gardens, which will all be at their best this month.

If you are online, look on the websites of the National Gardens Scheme, the Royal Horticultural Society (for its own and its partner gardens) and the National Trust for ideas. Many gardens have activities for children during the long summer holiday; in Clumber Park’s Walled Kitchen Garden there is a garden trail for children, ‘Gertrude’s bloomin’ moovelous summer trail’. Gertrude is our ‘scare-cow,’ helping to keep squirrels off strawberries and pigeons off our cabbages. Trail activities include the cow pat splat game, finding the lost herd and “milking” a cow.