Cultivation of rhododendrons

Rhododendrons are available throughout the United Kingdom: indeed it would be surprising to find either a Garden Centre or general nursery without some Rhododendrons on offer. However, the range of plants, both hybrids and species, is likely to be very limited in the majority of retail establishments, especially if most of their stock is bought in. For the discerning Rhododendron enthusiast, it will be necessary to visit (or contact) one of the specialist Rhododendron nurseries.

The advantage of dealing with specialist growers such as those listed, is the given details of the plants they are able to supply. For example, they will list the older as well as the more recent introductions, which are seldom to be found in garden centres. They will also offer a wide range of interesting species.

How to select plants best for your enjoyment
Select plants that show no signs of neglect by the retailer, especially inadequate watering, as evidenced by wilting or by brown edges or tips of leaves. be sure plant size, shape, foliage, texture and flower colour fit your landscape needs.
Extract from ARS cultivation guide

Another source of supply is the sales area in gardens open to the public. They may not have what you are looking for, but might have what you didn’t expect to find.

But it is not necessary to buy plants, and many enthusiasts grow their own, either from cuttings or seeds. Membership of the Scottish Rhododendron Society is a help to those choose this method of acquiring plants. Our parent Society, the American Rhododendron Society also operates a Seed Exchange, and members can buy seed of both species and hybrids. A wide range of seed is on offer and members who have availed themselves of this facility, report excellent results. Naturally, it takes longer to flower Rhododendrons from seed, but dwarfed forms can be expected to flower within a few years – whilst the larger leaved plants take longer, ten to twenty years in some cases.

Soil is very important. It needs to be well-drained and porous; preferably acidic. Our soil is seldom perfect but easily improved unless, of course, it is alkaline – containing chalk or lime. Even this can be delt with, depending on the degree of alkalinity. In many soils, the addition of either ericaceous compost or forest bark will be adequate and should be incorporated with the existing soil. Hole filled with soggy peat in which the plant is placed, should be avoided. Soil and added media should be well mixed. In wet situations, it is better to plant high. Having mixed the soil, compost and bark, make only a slight depression. Stand the plant in place and complete the job by mounding more of the prepared soil round it.

Success will also depend on the situation you have chosen for your plants. planting under trees that also have a shallow root system is unlikely to be satisfactory, as the resulting lack of moisture will cause the plants to look poor and fail to flower. Indeed in Scotland, shade is hardly a requirement for Rhododendrons, since the cooler climate prevents the extremes of temperature experienced in the South. Nevertheless, Rhododendrons are ideal in woodland areas, providing they have adequate moisture and sufficient light. Woodland can provide shelter from the wind for the bigger leaved forms of Rhododendrons, while the smaller dwarf Rhododendrons are happier in a more open location, such as a rock garden. Cultivation after planting, should be kept to a minimum: forking or hoeing under them should be avoided: mulching with bark or other organic materials is all that is required. Once planted in the right conditions, Rhododendrons more than any other plants, are able to look after themselves.

Ed Wright.