The Joy of An Acid Bed
16 February 2004

If you have limy, alkaline soil you probably don’t know what you are missing. There are wonderful plants that insist upon a soil with a pH well below 7. Below that is acid while a reading above 7 is lkaline. Most soils in Northern Ireland are alkaline or neutral with the peaty areas of Fermanagh and Tyrone truly acidic.

It is pointless growing acid loving plants on a limy soil. The foliage will become pale green or yellow and the plant will be stunted. A 12 inch high raised bed may be formed with timber or brick sides. Obtain a supply of peaty soil and add additional peat as the bed is filled. It is possible to do the same job without the raised sides. Form a mound
of suitable soil on top of the limy ground. Plant the deeper rooted plants in the centre of the mound with shallow rooting material close to the edge where there is only a thin layer of suitable soil on top of the
original limy soil.

Where the soil is wet, construct pipe and stone drains. Heavy soils can be lightened with the addition of coarse sand or grit. There are so many excellent, acid loving plants to choose from. With rhododendrons there are shrubs of tree-like proportions while others have leaves 18
inches long. Some species will only grow 18 inches high making them ideal for the front of the bed. Evergreen azaleas and those that are deciduous are now also to be found listed under rhododendrons.

Evergreen pieris are perfectly hardy but dislike cold winds and early morning sun when the foliage is red. They are in a class of their own with bright red or bronze young leaves in spring and lily-of-the-valley
-like clusters of creamy-white flowers at the same time.

The calico bush, Kalmia latifolia, produces its flowers in June. Before they open, the tightly crimped buds resemble icing sugar sweets. There are varieties ranging from white to deep pink. Usually the flower
buds are a deeper colour than the open flower. Heathers are a must for the acid garden with a range of species and varieties to ensure flower or leaf colour throughout the year. Some such as Erica carnea can tolerate limy conditions and may be planted where the imported soil is shallow.

Gaultheria mucronata used to be called Pernettya mucronata. It has small, glossy, dark evergreen leaves. In late autumn the shiny, bead-like berries are available in colours ranging from white through pink, red and crimson to purple depending on variety. It may be used to form a low-growing, colourful evergreen hedge.

Fill any gaps in the planting design with candalabra primula. They make a wonderful display in late spring and early summer with tiered heads of flower. Primula florindae, the giant cowslip exudes a wonderful fragrance.

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