Plant Profile: Persicaria

This genus of herbaceous perennials and annuals occurs almost worldwide and is commonly known as Bistort or Knotweed. Persicarias come in all shapes and sizes from the tall and flamboyant Persicaria alpina (syn. polymorpha) to the ground-hugging, tiny-leaved Persicaria vacciniifoliaAlthough Persicarias have a reputation of being invasive, they do have value in the garden if you have the space. They will grow on almost any soil and in sun or shade, flowering for a long period in varying shapes and shades of red, pink and white. They are self-sufficient in the garden, tough, hardy and long-living plants and don't need staking or fussing. Sadly, despite all these wonderful attributes people can quite often be seen running for the hills when I mention growing Persicarias in their gardens (only joking. but people are wary of them).

Persicaria polymorpha

Persicaria polymorpha

Persicaria amplexicaulis and it's varieties liven up a border with their tall, airy flowers, growing happily in amongst grasses and other perennials where it will tolerate most soils. Left to its own devices it will form a sizeable plant after three or four years. The large, dock-like leaves appear from large clumps of roots, covering the ground and smothering out any weeds below. The flower-spikes appear from early to mid-summer (depending on the variety), often to the worst frosts. The flowers are not dense or overpowering, but add structure and interest amongst other plants in the border, almost like Gypsophila in a vase of flowers. Shorter, ground covering varieties like Persicaria affinis 'Donald Lowndes', Persicaria affinis 'Superba' and Persicaria vacciniifolia will cover a few metres if allowed, which makes them ideal for covering bankings and other more challenging garden areas. 

Persicaria amplexicaulis 'Firetail'  

The flowers vary in size and colour: from the dark red of Persicaria amplexicaulis 'Firetail', the salmon orange of Persicaria amplexicaulis 'Orange Field' and the pale pink of Persicaria amplexicaulis 'Rosea' to the delicate white of Persicaria amplexicaulis 'Alba'. The distinctive pink "mini milk" flowers of Persicaria bistorta 'Superba' appear early in the Persicaria season, flowering right through summer. Then there is the bi-coloured flowers of Persicaria affinis 'Donald Lowndes'  and Persicaria affinis 'Superba' so, as you can see there is something for everyone. I love them all but perhaps especially the pale pink of  Persicaria amplexicaulis 'Rosea' amongst tall grasses and perennials. See them all in the nursery gardens. 

Persicaria bistorta 'Superba' in the stream garden

Because of their toughness and ability to cope with most soils (except very dry soils), sun or light shade they are great in mixed borders, prairie gardens and the more exposed, colder gardens of Scotland. I have successfully grown them in the nursery gardens, here on the side of an exposed hill in central Scotland at 850 feet above sea level, in clay soil. Their pretty shades of pink, white and red go well with other pinks, mauves, blues and whites. I have teamed them up with grasses, Veronicastrums, Echinops and Asters. I have included a photo of Persicaria 'Red Dragon' as an example of the showy colourful foliage some Persicarias have, sadly this is not hardy here in our corner of Scotland. I've tried it for a couple of years here in the nursery with no success.

Persicaria amplexicaulis 'JS Calor'

Persicaria amplexicaulis 'Alba'

If you have a space in your garden I would recommend you give these plants a go. Which one to go for depends on your colour preference. I have grown all these cultivars in exposed gardens on clay soil. The Quirky Bird recommends the following which are all available from the nursery:

Persicaria affinis ‘Donald Lowndes’ AGM 
Tough little ground-cover plant that is suitable for growing on a dry bank, an old wall or for softening the edges of paving. Short spikes of pale-pink flowers turning dark red in summer over glossy green leaves with good autumn colour. H 20cm, S 100cm.
Persicaria affinis ‘Superba’ AGM                                                                                     
A great low growing ground-cover plant that is suitable for dry banks and ground cover. Short spikes of pale-pink flowers turning dark red in summer over glossy green leaves with good autumn colour. H 20cm, S 100cm.             
Persicaria amplexicaulis ‘Alba’
One of my favourites, this rarer and less vigorous form has delicate, wispy, often branched spires of pure-white flowers with tiny, royal-purple stamens from July to the first frosts. Not as enthusiastic as some varieties and lovely in mixed borders. H 80cm, S 60cm.

Persicaria amplexicaulis 'Atrosanguinea'
Plentiful dark red spikes come out at all angles on a bushy but lax plant with light green leaves. All the usual characteristics of Persicaria amplexicaulis varieties. H 1m, S 1m.                         

Persicaria amplexicaulis ‘Firedance’
A vivid, salmon-red flowering Persicaria and the finest of several selections by Piet Oudolf. Well worth a place in the garden for its, enthusiastic growth, making it good for ground cover and its long flowering period. H 90cm, S 100cm.                                                                     

Persicaria amplexicaulis ‘Firetail’ AGM      
Stonking cultivar with numerous erect, fiery crimson spires on tall stems over bushy, green-ribbed foliage tinged red at the tips. Flowers from mid-summer until the first frosts, when the whole plant collapses until the following spring. Stunning with Persicaria amplexicaulis ‘Alba’. H 1.2m, S 100cm.

Persicaria amplexicaulis ‘Inverleith’            
Vigorous plant with lots of short, divergent to upright spires of dark crimson-red flowers on a lower-growing plant with excellent weed-suppressing foliage. H 45cm, S 100cm.                                          

Persicaria amplexicaulis ‘Rosea’     
Numerous erect spikes of graceful, light-pink flowers for months on end. A very effective screening plant that can provide privacy without cutting down on light levels. Grow something more colourful behind it that will ‘shine’ through or use to knit planting schemes together. One of my top plants of all time! H 1.4m, S 100cm.                                         

Persicaria bistorta ‘Superba’ AGM
Enthusiastic spreader with stubby, pale-pink pokers described by a young visitor to the nursery as a ‘Strawberry Mini-Milk’. Brilliant against a dry-stone wall or with a multitude of other border plants. H 75cm, S 100cm.                                 

Persicaria polymorpha
A true giant of a plant! Stout, branching stems which are smothered in a mass of tiny, cream flowers in summer, ageing to bronze-pink in autumn. Tough, self-supporting and non-invasive. H 2m, S 100cm.     

Persicaria amplexicaulis 'Rosea'

Persicaria amplexicaulis 'Firetail' 

Persicaria amplexicaulis 'Inverleith'  

Persicaria microcephala ‘Red Dragon’

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