Gardeners Corner - Alpine beds and rock gardens
I'm sure most of you who have been hiking in the mountains will have noticed the various rock plants and alpines that grow there. Alpine plants will find a home in dry stone walls, screes, nooks and crannies and alongside streams. Rock and alpine plants are perfect for exposed and seemingly inhospitable places but they can also be adapted to your garden. As you explore the prospect of adding a rock garden to your home, you will find that it is a surprisingly lovely way of adding colour. The rocks will bring a contrast in texture and the plants are beautifully elegant in their detail. Whether you have ever been inspired to recreate the natural beauty of mountain landscapes in your own garden or you’re approaching this as an exciting new idea, I'd like to share with you some basic things that you can do to try and accomplish just that.
Rock gardens are generally on slopes or tiered mounds, and whilst you could create one on the flat this will not show the feature to its best advantage Try to select an area that has a natural slope as this will save you a lot of time and effort. If you’re starting from scratch on a flat surface, begin by piling a mound of sub-soil in your chosen location, although it’s down to personal choice, using as much space as possible for your rock garden will mean you can be more creative, using more rocks, alpine plants and . if you are feeling ambitious,even throw in a few streams and small ponds.
Once you have your mound of sub-soil in whichever shape or size you prefer you can add a layer (about 4 to 5 inches deep) of compost (preferably a peat alternative). Next you can position your rocks, be creative and place them in different positions on and around the mound, cluster some together and have a few on their own. If you are putting them in a cluster, be sure to fill any gaps between the rocks with compost so that your plants have something to grow into. Once you have planted all your alpines and rock plants, you will need to create a scree. If you are wondering what a scree is, it's what you often see at the base of steep slopes on mountains where a huge amount of rock, stones, gravel, slate and debris has slid down the mountain and piled up at the base in usually in a fan shape. This is optional feature, but it will significantly enhance the appearance and functionality of the rock garden as you can plant additional plants in the scree, it also helps with weed suppression. You can use the materials like gravel, slate, stones or something similar, it's basically like a mulching except a rock garden alternative. Be sure not to use anything to big as that wouldn't be effective both visually and physically. Below is a short list of different rock plants/alpines and their preferred settings:
Exposed sites (rock plants that tolerate exposed/windy sites):
1. Antennaria Dioica is a very low maintenance plant that is a semi-evergreen perennial. It has spoon-shaped leaves that spiral up the stems which are white and hairy. With stems up to 10cm in height, it produces fluffy white or pink flower-heads in late spring and early summer.
2. Crepis Incana is another low maintenance plant. It is a herbaceous perennial that grows up to 30cm tall, it produces a rosette of greyish-green jagged leaves and open blooms of light pink 'dandelion' looking flowers about 3cm wide.
3. Sempervivum 'Othello' is one of the more common alpines, it is not as low maintenance as the previous two, It will need checking occasionally for pests such as vine weevils. It is an evergreen with large dark red rosettes of broad fleshy leaves. Star shaped pink flowers are produced by older rosettes in summer. Though individual rosettes die after flowering, each plant will survive by forming offsets.
1. Ajuga Pyramidalis is generally low maintenance but it will need leaves removing that have a powdery mildew on them. It is a clump-style semi-evergreen perennial with a basal rosette of dark green leaves, small tubular dark or pale blue flowers are produced among dark purple bracts in a pyramidal spike about 10cm tall in spring and early summer.
2. Genista sagittalis has medium maintenance requirements. It will need checking for pests and diseases and a winter pruning. Be careful not to cut into old wood. This plant is a low growing almost horizontal deciduous shrub to 15cm tall (or long if flat on the ground). It will form a wide mat of flattened, upright stems bearing sparse small leaves with clusters of yellow flowers 10mm long, in early summer.
3. Waldsteinia ternata is a low maintenance rhizomatous herbaceous / semi-evergreen perennial that produces clumps of divided leaves. It has saucer-shaped yellow flowers 1.5cm across that bloom in loose clusters in late spring and early summer.
1. Androsace launginosa is a medium maintenance plant that requires removal of pests, diseases and dead growth. It is a trailing evergreen perennial, it’s perfect for ground cover, spreading up to about 45cm wide. This plant is composed of loose rosettes of grey-green ovate leaves and dome shapes of bright lilac-pink flowers 8-12mm wide on stalks of 10cm which open in midsummer.
2. Linaria Alpina is also a medium maintenance plant that requires removal of pests or diseases and any leaves with mildew on them. It is a short-lived perennial with trailing stems bearing narrow blue-green leaves with bi-coloured purple and orange flowers that are about 2.5cm in length which are produced in summer.
3. Sempervivum calcareum 'Extra' is a medium maintenance plant that requires the removal of pests and diseases such as vine weevil and rust (a disease that appears as rusty coloured leaf spots) this plant has many symmetrical rosettes in a circular shape, about 20cm in diameter, and the leaves are bluish green with dark red tips. The inflorescence is a little sticky and its petals are white, flushed green at the tips and pink at the base with reddish purple filaments. This is quite an interesting plant and one of my favourites.
For further information on alpine and rock beds I'd recommend a book called 'The Royal Horticultural Society Encyclopaedia of Gardening' – specifically the rock garden section, though it is a great book in general. Winterbourne Gardens also has an alpine glasshouse and is free for staff to visit, just take along your ID card. You can also follow them on Twitter, Instagram and Facebook.