Sandy’s Garden ... Portulaca Grandiflora

Sandy Simpson
Sandy Simpson

A couple of weeks ago I wrote a column about a plant with the botanical name Portulaca gilliesii.

It was named in honour of John Gillies, M.D. (1792–1834), a Scottish naval surgeon who later became an explorer and botanist. In that column were the words, “The numerous species of Portulaca commonly grown nowadays under the specific names grandiflora or Thellussonii come from a single species discovered by the Scottish botanist Gillies in Mendoza in the republic of la Plata to the east of the Chilean Andes.” So what is Portulaca grandiflora which I promised to return to a fortnight ago?

Portulaca grandiflora is ‘the large-flowered Portulaca’ and is usually grown as a ground cover plant. Most gardeners will refer to it either as ‘purslane’ or by its most common name of ‘moss rose’, although the family of plants of which it is a member rejoice in a wide variety of common names, including green purslane, summer purslane, pigweed, pusley, little hogweed and golden purslane. In Norway it is called ‘portulakk’, while their neighbours in Denmark spell it ‘portulak’ and the Finns spell the word ‘portulakka’; the French call it ‘pourpier’; the Germans know it as ‘Gelber Portula’; it is known as ‘verdolaga’ in Spain; and the Chinese name for it is ‘ma chi xian’. From the wide geographical spread of its names, gentle reader, you will have gathered that versions of the plant are found all around the world. Indeed, there seems to be some doubt as to where the large-flowered species originated, the favourite candidates being Brazil, Argentina, Uruguay and their neighbours, which tallies nicely with John Gillies having introduced the plant to Britain from Chile.

I shall not attempt to improve on this description of moss rose, which is taken from a seedsman’s catalogue. “Moss Rose (Portulaca Grandiflora Mix) - Moss Rose seeds establish easily and produce the perfect ground cover plants for an eye-catching display of long-lasting, tropical color. Portulaca Moss Rose works well in hot, dry garden spots. This mix of Portulaca seeds offers a collection of some of the most intense, colorful blooms you will ever see! The 2-inch flowers on these ground cover plants are fully double and beautifully shaped. The blooms stay opened for long periods of time, and they are nestled above the succulent foliage like shrub roses.” (I have retained the U.S. spellings and the seedsman’s capitalisation of the plant’s common name, although I prefer lower case for common plant names.)

The Royal Horticultural Society (RHS), in its weighty A-Z Encyclopaedia of Garden Plants, is, perhaps, rather less lyrical but nevertheless makes the plant sound pretty attractive, describing it as a “spreading red-stemmed annual with clusters of cylindrical, fleshy, bright green leaves, to 2.5cm (1 inch) long. In summer, it produces single or double, satin-textured, rose-pink, red, yellow or white flowers, to 2.5cm (1 inch) or more across, sometimes striped or flecked in a contrasting colour.” Low-growing, moss roses have a place in flower beds, containers and rockeries, and that prolific horticultural author Dr D.G. Hessayon writes, “A sandy bank in full sun is not easy to keep clothed in colour all summer long if the weather is dry – Portulaca is one of the few satisfactory plants for such a site.” He recommends sowing seeds in February/March in gentle heat, planting the seedlings out in May in well-drained, light soil where the plants will have the benefit of full sun.

Well, that requirement for full sun may make central Scotland less-than-ideal for moss roses today. But were we to have a guarantee that climate change really will make Scotland warmer with long dry spells, there are worse choices the gardener might make.