Following on from my post last week about physocarpus, I want to ignore the weather entirely and turn my attention this week to another shrub you may not have heard of: Diervilla. Like physocarpus, these are American shrubs, the few species all from the Eastern US states and all very similar, with opposite leaves and small, yellow flowers. They are most closely related to the weigelas, and are less showy, but bloom at the ends of the new shoots, unlike weigela, which means they can be pruned pretty hard in spring and will still produce lots of blooms.
Now I have to confess that the flowers are not the most showy of blooms but they are produced over many months and they are loved by bees and butterflies. There are few shrubs more beneficial to wildlife.
The reason you have probably not heard of them is because their charms are rather subtle. But before we get to the exciting bits I must explain why you should plant one, apart from the benefit to the bees.
Diervilla are hardy, tolerate light or hard pruning and they will grow in any soil and in sun or part shade. They do lose their leaves in winter but the autumn colour can be attractive. The wild forms grow to 2m or more and can sucker which makes them ideal for rough areas or large areas, where they have generally remained until recently. But plant breeders have been busy ‘improving’ the plants and there are now some excellent varieties that should be included in any garden.
First and foremost are the Kodiak (R) range. These are all compact, reaching about 1m high and wide. All have similar flowers but vary in foliage colour. Kodiak ‘Orange’ is a great shrub with amber/peach foliage that becomes orange in autumn and it flowers all summer. My plant is still only 75cm high and wide after three years and I wish it was bigger. It is always delightful throughout summer and mine is surrounded by Geranium ‘Rozanne’ which scrambles through it.
There is also ‘Red’ and ‘Black’ according to the foliage colour. I have now added ‘Black’ to the garden and the flowers are shown off much more effectively on this.
If you want something slightly bigger then choose ‘Cool Splash’ which has green leaves margined with creamy white. Like many variegated shrubs it can produce plain green shoots but these are easily pruned out.
And as if to emphasise the benefits to pollinators, one of the most popular of the new diervillas is ‘Honeybee’ which is also the tallest, at about 1.5m. The foliage is bright yellow, tinted with red at first and although the flowers do not show up that well the bees have no trouble finding them! Plant in full sun or partial shade if you soil is very dry in summer.
All these are proving themselves as tough, easy shrubs in my own garden and they are not bothered by pests or diseases so are ideal if you garden organically or want trouble-free shrubs to beautify your garden.
Weekly reminders
Complete the winter digging of the veg plot. Winter digging is especially important on heavy, clay soils because exposure of the dug soil to winter frost will help to break up the ‘clods’. Dig in as much organic matter as you can to improve the soil. And if you are going to plant peas and beans, brassicas such as cabbage and kale and other plants that do not demand acid soil, dig in some garden lime too. This will help improve your heavy soil and is an essential nutrient for most plants. You can buy Garden Lime in various-sized packs at Nags Hall now.