Growing Alpines
and Rock Garden Plants

These notes are written from a New Zealand gardener's point of view but we hope all gardeners will find them of interest.


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ALPINES are plants growing at high elevations, above the tree line.
They include the taller plants of alpine meadows which are often grown in perennial borders.
In rock gardening usually only the smaller alpine plants (approximately 15-30cm high) are used.
Many rock gardeners also include dwarf plants of suitable character and proportion from
non-alpine areas, such as coastal North and South America, steppes, prairies and deserts,
the mediterranean and north Africa, Australia and southern Africa.

The majority of rock garden plants like an open sunny position outside with good air flow
and a moderately fertile soil. They are unlikely to thrive where the soil becomes arid in summer
or where water will not drain freely away. Most will tolerate frost and snow but the foliage of
some plants will be damaged by freezing if the leaves are saturated with water.

A thoughtful selection of plants will provide you with colour for most of the year, perfume, berries
and autumn foliage.

Plants can be cultivated in a variety of ways so whatever your circumstances you can enjoy growing these beautiful little plants, even if you live in an apartment and have just a balcony.

rock garden ROCK GARDEN
An arrangement of rocks in the open garden to provide a home for alpines and rock garden plants.
As well as the more traditional terraced type of rock garden made on a slope, very satisfactory arrangements can be constructed on flat ground to simulate river flats or a boulder field.

view of river flats

view of a boulder field

rock garden constructed on a flat site Select your site away from buildings which may reflect heat or keep rain off, and trees/large shrubs which compete for nutrients and water.
On a flat site the soil can be mounded up at least 40cm to improve drainage.

Rocks If possible choose rocks which are all of the same material, for example all sandstone (or schist, limestone, river boulders or squarish blocks etc.) Use the largest rocks you can handle comfortably, with smaller pieces added during construction. Set the stones in deeply for stability and slope the top of each stone back into the soil so that water will flow to the plants' roots rather than over the front of the rock.

Soil should drain freely. Additional very well-weathered cow or sheep manure, compost, gritty river sand (like coarse sugar, not as fine as salt), and a dusting of dolomite lime dug in about two weeks before planting will all improve the soil.

Maintenance includes feeding in spring with a light sprinkling of dried blood and bone or balanced fertiliser around the plants, weeding, and removal of fallen leaves and a light trim back in autumn.


a dry stone wall planted with phloxes, aubrietia and trailing rosemary WALLS
A structure made to retain a bank or soil, often built of stones, bricks or other materials, with crevices and channels which can be planted up with cushion or trailing plants. Good choices would be Dianthus, Phloxes, Gypsophila, Aubrietia and Alyssum.


PAVING
A flat area, patio, terrace or paved path with crevices between the tiles or stones in which small cushions and mat-forming plants are grown.
Favourite plants for this area would include aromatic Thymes, perfumed small Dianthus, creeping Bellflowers (Campanulas)

view of a raised bed constructed of timber and filled with sand RAISED BED
A low retaining wall built into a sloping piece of ground or a free-standing structure of low walls filled with soil, with rock garden plants on the top and sides.
A raised bed is a good choice if you have physical limitations since the garden can be tended from a chair and plants and perfumes can be appreciated to the full without having to bend down.

this hypertufa trough is planting with silver saxifragas using pieces of limestone for the stones TROUGH GARDEN
A container filled with soil and planted up as a miniature rock garden. Usually movable depending on size and construction. These containers may be of stone, hypertufa (concrete with peat added), concrete, timber or plastic.
A suitable depth would be at least 30cm as shallow soils will overheat during summer.
You can site your trough in sun or part shade, with soils adjusted according to whether you want to grow plants preferring acid soils such as miniature Rhododendrons or some Primulas, or those which enjoy limy soils such as Dianthus, Saxifrages and Campanulas.
All containers must have at least one drain hole, covered with mesh to deter insects.
Fill the trough completely with your preferred potting mix (do not put large drainage material in the bottom) and mound it up to allow for settling. Set your selected stones on top.
Give the plants a good watering before and after planting and finish off with a top-dressing of small chips or stone which will be in harmony with the larger stones.
The fertiliser in most potting mixes is exhausted within a year so, as part of your spring routine, give your troughs a light dressing of your favourite general fertiliser or dried blood and bone.
An example of crevice planting in a hypertufa trough A round hypertufa trough
rock garden POTS
Alpine plants grown in clay or plastic pots, often preferred cultivation for exhibition specimens, or to enable specific cultivation requirements.
Plunging the pot into damp sand maintains a cooler root temperature during summer.

rock garden ALPINE HOUSE
A glasshouse or covered area with maximum ventilation along the walls. Plants are grown in pots on benches, or in raised beds in situ. Here again, plunging the pot into damp sand will keep the roots cooler in summer. Enables management of overhead moisture but needs to be shaded from mid-September until April in New Zealand.

rock garden SAND BEDS
A sand bed is a method of growing alpine and rock garden plants in pure sand to avoid humus which might produce moulds and rots.
For our beds we used crushed river sand with the finest silty material removed. The particle size ranges from the size of coffee sugar up to that of rice.
All potting mix was shaken from the plant roots and granulated or slow-release fertiliser worked into the sand at planting time.
The beds are in full sun and the upper 15cm of sand gets very hot and dry in midsummer. In the evenings we watered thoroughly with a hose. Autumn planting is much more successful than end of winter or spring planting as the plants have time to establish a good root system. Weeding is easily attended to and because the beds are in full sun we are not troubled with liverworts. Successes include New Zealand alpines such as dwarf Carmichaelias, Myosotis, cushion Celmisias, Raoulia eximea, Dracophyllums and Kelleria. Eriogonums, dwarf Yucca and cushion Phlox species from North America thrive (but not Astragalus or Oxytropis). Silene, Arenaria, Geranium, Wahlenbergia serpyllifolia major. Of the bulbs, Allium karataviense, North African Narcissus species and miniature Tulips are good and Oncocyclus Iris do well but the rhizomes must be buried deeply and the foliage protected from rain all summer. We recommend this method of cultivation as the plants stay in character, flower well and weeding, while not non-existent, is very easy.



PLANT CATALOGUE

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Hokonui Alpines, Croydon Siding Road, R.D.6, Gore 9776, Southland,
New Zealand
Telephone,Fax 03 208 9609.
Email us Hokonui Alpines