THE fragrant rhododendron is one of the most sweetly scented plants at this time of year, or any other time. Many of the rhododendrons grown in gardens have no scent, although some have, but none is as richly perfumed as the fragrant rhododendrons, the best known of which is Rhododendron 'Fragrantissimum'.
The name 'fragrantissimum' means 'most fragrant', and it is most fragrant, exuding an enchantingly rich, yet sweet and light scent from white trumpet flowers. It is not a house plant but can be taken indoors when in flower.
The plant is a hybrid of two Himalayan species, Rhododendron edgeworthii and Rhododendron formosum. The 'edgeworthii' part of the name honours Michael Pakenham Edgeworth, an amateur botanist, who worked for the East India Co in the middle of the 19th Century and who had connections with Edgeworthstown, Co Westmeath, although he did not actually discover the species.
Neither of these species or their offspring is fully hardy, except in mild areas near the coast, which is why they are generally grown as a greenhouse or conservatory plant. It is well suited to being grown in a pot because the Edgeworth parent is found in the wild growing in the mossy leaf litter on large tree limbs.
It has a mass of very fine roots and can fill the pot and still grow well. The plant is a bit straggly with lax stems that flop about. This can be countered by pruning the longer shoots immediately after flowering. After flowering, the plant can be kept under a greenhouse bench or in a part-shaded area.
It can be placed outdoors in its pot from mid-June to late August, given regular watering to keep it moist and a liquid feed every three weeks or so. As the plant gets bigger, it will need to be re-potted every few years and this can be done with a mixture made of acidic soil and leaf mould or peat.
Apart from 'Fragrantissimum', there are several closely related named varieties, some of them hybrids of 'Fragrantissimum' or Rhododendron edgeworthii. 'Actress' has a red flush to the outside of its flowers. 'Lady Alice Fitzwilliam' (shown) is flushed pink with stripes. 'Princess Alice' is white with a yellow eye. 'White Wings' is also white with a yellow eye and heavily scented.
These related varieties are occasionally seen for sale when in flower. They all root easily from cuttings taken of new growth from mid-summer, and the new plants can be grown on in small pots. Use lime-free water, rainwater if necessary.