One of the Persicaria we’re not judging on the RHS Persicaria Trial Forum is Persicaria orientalis because it’s an annual while the rest are perennial (trials are on hold for now due to lockdown). For inexplicable reasons this plant is also called Kiss Me Over The Garden Gate. It’s fast become one of my favourite plants and a key component of our garden at home.
About Persicaria orientalis
Persicaria orientalis is a hardy annual plant that will grow, flower and set seed all in one year. It is thought to be native to the eastern and south eastern regions of Asia across to north and eastern parts of Australasia.
It will grow well in full sun to part shade and likes rich moisture retentive soils. Personally, I find it will grow perfectly well in varying degrees of shade but will grow taller and flower later. Some say it flowers from July while others say not until September.
In our garden with only half a day of sun, it starts flowering only from September, generally. I also find it will tolerate drought fairly well and I have grown it in large pots (30cm+) as well as in the ground.
Curiously, most retailers list this as growing to about 150cm when I find it shoots far above head height to easily reach 200 – 300cm. It would combine really well with equally tall sunflowers. There is a shorter cultivar called ‘Cerise Pearls’ so I suspect along the way this has mixed into the seed provider chain to become the shorter version they are talking about.
Why I love Persicaria orientalis
I memorably first fully appreciated Persicaria orientalis at The Salutation in Kent, its towering plumes of pink tassels hovering over the lower plants. I was with my friends Steven Edney, head gardener of The Salutation, and Philip Oostenbrink, head gardener of Canterbury Cathedral, who were showing me around. I commented how much I loved the mass planting of it and it would work perfectly in my own garden for the height and colour.
In Philip’s own garden he too was growing it in wonderful combination with the large leafed Solanum quitoense. Back in Steven and his partner Louise Dowle’s garden, they had even more. Louise is known as the propagation queen and legend has it that she can germinate even the most challenging of seeds. Persicaria orientalis is a tricky badger to grow from bought seed but Louise knows the secret.
It’s a plant that will always remind me of this dynamic Kent gardening trio. And I’m happy that I have it, originating from their batches because Philip gave me some seedlings a few years ago. They’ve reliably self sown here ever since taking me back to their gardens when I see it.
How to grow Persicaria orientalis from seed
I originally tried growing Persicaria orientalis from bought seed but I only had one plant germinate. It’s a tricky plant to germinate in this way because the seed requires a period of cold stratification, where it goes through a month or so of temperatures below 5C mimicking winter. This tells the seed it has made it through winter into spring and is time to grow.
I tried replicating this in the fridge but as I say, it didn’t work very well and I find cold stratification is quite often best left to nature by scattering some seeds around in autumn and letting winter do its thing. As a hardy annual it will self seed readily and can in fact become slightly out of control if you take your eye off the ball, especially around streams and rivers. Though in gardens it’s perfectly easy to manage and nothing to worry about. it’s easy to pull the obvious seedlings.
My personal advice would be to do as I did, find some seedlings to grow on in the first year and then let the plant do what it does best, self sowing about the place forever more.
Persicaria orientalis care
These are trouble free plants that don’t really need any looking after at all, they’ll happily grow away quickly. One little tip is that if your plants are slow to flower, as mine can be, is to use a little fertiliser in midsummer rich in potassium. I use organic tomato fertiliser based on seaweed and found last year that a few doses of this can speed the plant toward flowering a little faster. Don’t overdo it though as they generally prefer life on the tough side.
Last year I was interested in which Persicaria can be propagated by root cutting and I found Persicaria orientalis is one that does root quickly and easily. I popped a stem segment in a glass of water and roots appeared within days. I’m not sure why you would ever want to actually do this as once you have it established in your garden you’ll never be short of plants, but I found it interesting.