A Purple Patch

Contributed by Ginny Oakes

On September 26, 2008

A purple patch – a period of success or good fortune

 What better way can there be to spend a bleak mid-winter afternoon than mulling over last years gardening successes – and failures – and looking forward in anticipation to what might be achieved in the coming year? It was on just such an occasion that I came across these shots and remembered how much pleasure these two plants had given and what a lot of comment they had attracted from everyone who visited us – but for somewhat different reasons.

Now I know we’re the Hardy Plant Society and I know these plants are not hardy here in the UK but I think most of us grow at least a few tender plants in pots for summer display so I thought you might like to consider these two candidates for that role.

Pennisetum setaceum is native to tropical Africa, southwestern Asia and the Arabian Peninsula. Although perennial, it is usually grown as an annual from seed each year. It has green leaves and purplish pink racemes of flowers.

But here we have Pennisetum setaceum ‘Rubrum’, Purple Fountain Grass, which has purple foliage and flowers. It is, I think, fairly new to most of us but everyone I know that has seen it has been enthralled. As is often the case in the Hardy Plant Society, this plant was passed around and I first had it from a friend who has a small nursery and had had it passed to her for save keeping.

Opinions vary on its cultivation and propagation so perhaps it’s best to concentrate on our experiences here in Kent.

Once the weather warms up it grows very fast and needs potting on regularly so that it does not become pot bound and dry. It requires full sun to develop the best colour. Given this treatment and some feeding it develops a clump of deep purple leaves with upright flower stems. As they develop, the racemes of flowers darken to rich red, extend to some 30cm long and arch over, giving the plant its characteristic fountain shape. It grows to about 90cm high and 60cm wide. It is tender and does not survive prolonged temperatures below 4˚C. The books say it rarely sets seed and I certainly haven’t found any, so plants must be over wintered and this is where the problems start. My first plant I treated in the same way as agaves and other succulents but this was too cold and too dry for the pennisetum which shrivelled and never recovered. My second effort has also perished but, not to be beaten, I will be trying again this year. If it grows well I will try propagating it as, having taken advice, division during the summer, when the plant is growing fast, would seem to be the best bet. Small, green plants, which can be more easily accommodated and kept warm and watered stand a better chance of survival. Someone else tells me that stem cuttings from the growing stems can also be made with some success. Ensure that they have at least one node, (which manifests itself in grass as a swollen joint) and cut as far down as possible. Then lay them in shallow water in a warm place and hopefully they will root from each node.  Pot into gritty compost mix. 100% success cannot be guaranteed but it sounds worth a try.

So, what is it about this plant which is so appealing? The colour, the shape, the habit or a combination of all of them? And why does my second candidate get such a different response?


Pennisetum glaucum ‘Purple Majesty’ is not to everyone’s taste! I like it. It’s big, it’s bold and it makes a statement. But other peoples’ reactions are somewhat more circumspect. I bought my plant at a local boot fair, when the red foliage caught my eye, and immediately set about some research.
Pennisetum glaucum, Pearl millet, has been grown as a cereal crop in Africa and parts of the near east for the last 3000 years and is grown for forage and grain in many countries throughout the world. Recent breeding programmes in the US have produced pearl millet hybrids for grain production and it was on one such programme at the University of Nebraska that an unusually coloured plant was noticed amongst some potential breeding stock from India.

It was no help in the programme but was placed in the genetics nursery where, over time, odd characteristics were discovered but nobody saw its ornamental value until a keen-eyed nurseryman on a visit saw the purple millet and suggested that it was entered in the All-America Selections contest. Several purple pearl millet selections were looked at and the Purple Majesty hybrid made from the most desirable parents before entering it in the AAS competition. In 2003 it earned the organisation’s prestigious Gold Medal for its exceptional garden performance.

‘Purple Majesty’ is an annual for a well-drained sunny site. It can reach 1 – 1.5 metres with very wide, purple leaves with a red midrib, growing up the stem. Each stem develops a huge 20cm-long flower head, also purple. This is shimmery at first then turns yellow for a day or two as the pollen is shed. It is then a rather dull brown for a while until the pink seeds develop, like little jewels, giving it a new lease of life. Sunlight is again essential to develop the purple colour and although it will tolerate a poor dry soil it responds well to feeding and watering.

So there you have it – “Tall, dark and handsome” and an American celebrity to boot! And even if you still don’t like it, you have to admit it’s a great story.

1 Comment

  1. mervyn brown

    I agree Pennisetum setaceum ‘Rubrum’ does not overwinter well, not outside or in a polytunnel. I have succeeded with this plant with only one method, which is to bring it indoors and not let it go fully dormant. It is true you can root it very often by placing in water, when it will strike roots from the nodes. I have had no success with germination from seed, which may well have been infertile. I am a volunteer gardener at Hall Place, Bexley and I am interested in those plants which are marginally hardy. Callistemon citrinus sets seed and germinates sparingly around the mature bushes at Hall Place. Delosperma cooperi thrives, but Lampranthus roseus succumbed to our recent spate of cold weather. Acacia pravissima managed to survive the cold spell too.

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