Choosing Bulbs for the Rock Garden

Rock and alpine gardens are often made in odd corners as well as in more prominent situations. Wherever they may be placed, in sunshine or shade, there are showy bulbous subjects which can be used to give a lovely display. Plantings should be quite informal in character and this is the main reason why the smaller growing or miniature bulbs are so suited for cultivation in the rock garden and they can be chosen to produce colour at different times of the year.

After you have made your selection of the better known and more conventional subjects, look for some of the less common and choose some with which you may not be familiar. These are often found under the heading ‘miscellaneous’ in the majority of catalogues. Most have no special cultural needs and you will be pleasantly surprised by the delightful display you will secure.

In a well-made rock garden, there are crevices and interstices where little groups of three or more can be planted. They usually increase to give a bold display after a year or two. While it is true that muscari and a few other bulbs can be placed so that they penetrate a carpet of growth from perennial rock plants, only a few are successful under such conditions. Most, particularly the choicer kinds, are happy where they are unhampered and where the ground is clear around them so that their foliage can mature properly and the bulbs obtain the ripening they need. Although colchicums are suitable for selected positions in the rock garden, they should be placed with care for their foliage may block out or even smother nearby smaller plants which develop later.

If the soil is on the heavy side or water from surrounding ground is liable to drain on to the site, it is advisable to plant on slightly raised beds and mounds. In fact, this treatment is advisable for subjects that die down in the early summer so that they can dry off for a short period.

Apart from their value for giving a display in the front of the border or for naturalising, the following are ideal for the rock garden whatever its size.

Anemone blanda has beautiful star-shaped flowers in blue, pink, mauve or white which brighten the rock garden in March and April, as do the lavender-blue, daisy-like flowers of A. apennina. A. fulgens, which yields scarlet flowers in April—May, and St Bavo, with lovely pastel blooms at the same time, are also suitable in sun or partial shade. Plant all these in early autumn about 2 in. deep and 4 in. apart. Wait until March or April to plant the large-flowered de Caen and St Brigid anemones which come in many brilliant shades of red, purple, mauve, rose and white.

Chionodoxas, Glory of the Snow, should be planted in September or October 2 to 3 in. deep and 1 to 2 in. apart. They bloom as early as February continuing into April and grow about 6 in. high. Chionodoxa gigantea has light blue flowers with a white centre; C. luciliae is lilac blue with a pale star-shaped centre while C. sardensis is bright blue.

Crocus species will provide a continuous show from January onwards. Crocus chrysanthus has many varieties in white, primrose, canary yellow, golden and bronze shades as well as pastel blue. C. susianus, the Cloth of Gold crocus with bright yellow-orange flowers, appears by mid-February. C. tomasinianus is silvery lilac. By the end of February the pale greyish-lavender buds of C. sieberi open to reveal a pure lilac interior with golden-orange throat. The large-flowering Dutch hybrids show colour from March. Plant all these crocuses in September or October placing the corms 3 to 4 in. deep.

The Winter Aconites break through the ground early in January providing a cheerful show with their buttercup-yellow flowers. Plant the tiny tubers in autumn 2 in. deep and 2 to 3 in. apart. Eranthis hyemalis, golden yellow, is the earliest to bloom. E. cilicica, with deeper yellow blooms, bursts forth a little later as do the much larger golden-yellow blooms of E. tubergeniana.

The Snake’s Head Fritillary or Fritillaria meleagris is so called because its nodding, bell-shaped flowers, carried on slender foot-high stems, are spotted and chequered rather like the skin of a snake. They are in shades of purple and white and are produced in April and May. They should be planted in autumn in cool positions about 3 in. deep.

Snowdrops have frosty-white, bell-like flowers as early as January. Plant in autumn about 4 in. deep and 2 to 3 in. apart in moist humus-filled soil in light shade. In addition to the common snowdrop, Galanthus nivalis, try the double-flowering form, Galanthus nivalis florepleno.

There are a number of the dwarf species of Iris which flower from January to March. They include the sweetly scented Iris bakeriana, lavender blue; lris danfordiae, lemon yellow; Iris histrioides major, blue; and lris reticulata, violet, which has several sweetly scented forms. All grow from 3 to 9 in. tall and are long lasting. Plant them in the autumn about 4 in. deep in semi-shaded positions where their rich colourings are more pronounced and their flowering period is lengthened.

Leucojum vernum, the Spring Snowflake, sends up white flowers tipped green on 6-in. stems, looking rather like a choice snowdrop.

The lovely little Puschkinia libanotica has silvery-blue flowers with deep blue stripes in late March and April.

 

 

Grape Hyacinths brighten the rock garden from February onwards. Chief among the species are Muscari armeniacum, in bright shades of blue, and the unique Muscari plumosum or Feather Hyacinth which has large heads of plume-like violet flowers in May. Plant muscari in autumn 3 in. deep and 2 to 3 in. apart.

Erythronium dens-canis, the Dog’s Tooth Violet, produces flowers in lovely delicate shades of white, pink, rose and purple in March and April. Its marbled foliage is attractive even after flowering time is over. Purchase mixed hybrids or named varieties and plant in autumn in peat-rich soil in somewhat moist shadowed places in the rock garden or border. Plant erythroniums in groups, placing the bulbs at least 6 in. deep.

Ornithogalum umbellatum, Star of Bethlehem, produces white blooms shaded green on 10 to 12-in. stems in May. Plant in autumn about 4 in. deep and 3 to 5 in. apart.

Scillas like positions that are open and sunny in the winter. Flowering from February onwards, Scala tubergeniana produces silvery-blue flowers on 4-in. stems; S. bifolia is 5 in. tall and sky blue shading to pale blue, and its variety rosea is pink. S. sibirica produces cobalt-blue flowers on 4-in. stems in March and April, while the variety Spring Beauty has bright blue flowers on 6-in. stems. There is also a lovely white form.

The dwarf narcissi are ideal for rock gardens for they mingle well with creeping plants such as aubrieta, campanulas and raoulia. The tiniest of all is Narcissus minimus, a really delightful variety with golden flowers appearing in February and March on 2 to 3-in. stems. The varieties of N. bulbocodium are both quaint and attractive. The form known as conspicuus is often referred to as the Yellow Hoop Petticoat, while there is also a white variety, both growing 6 in. high. The Cyclamineus varieties produce exquisitely formed, long lasting little trumpets and they are available in separate shades of yellow. N. triandrus albus is the Angel’s Tears Daffodil producing on 7-in. stems clusters of elegant creamy-white flowers in March. N. nanus has a clear yellow trumpet and grows 4 in. tall. There are many forms varying in height from 8 to 12 in. Whichever of these dwarfs you plant you will be delighted with the display and the interest they provide.

Oxalis adenophylla is one of the best of this large family producing pretty dainty lilac-pink flowers throughout the summer. It forms a compact rosette of silvery leaves.

Sparaxis like sunny well-drained positions where they will produce their richly coloured flowers on 6 to 9-in. stems. Particularly good is the variety Fire King with its flaming red blooms.

Triteleia, sometimes known as milla and classed now as brodiaea, produces its starry sweet-scented bluish-white flowers in May on stems 4 to 6 in. high.

07. July 2011 by admin
Categories: Bulbs and Corms, Gardening Ideas, Plants, Rock Gardens | Tags: , , | Comments Off on Choosing Bulbs for the Rock Garden

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