Container Gardening with Harriet Rycroft, week 4

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The final week of the container gardening course with My Garden School. ‘Summer Luxuriance’, it’s entitled, and brimful of information to help you take full advantage of the long days and warm temperatures. Containers should be bursting with fabulous foliage and jewel-bright punches of floral colour from June well into September and beyond, and Harriet guided us through with advice on plant selection, what to grow in sun and shade, as well as some useful tips and tricks, such as growing climbers in pots, and using them to weave in and out of the display.

Irrigation is of course of prime importance during the hottest months, and watering methods were covered, along with other maintenance tasks such as feeding and deadheading.

Once again I was thrown something of a curve-ball by the assignment, in which we were asked to base a container display around our favourite colour. I’ve come to the conclusion that I don’t have a favourite colour, tending to base my planting ideas around either harmonious or contrasting colour combinations, rather than monochromatic schemes, which can seem a little flat. So, I have favourite colour combinations to which I return time and again – greys and pinks, greys and yellow, lime green and deep red tones, to name but a few. If there’s one colour to which I’m drawn, it would those tones variously described as black, or burgundy, or deep red-purple – as with the foliage of Cotinus coggygria 'Royal Purple', or Actaea simplex 'Brunette', for example – and so I took this as my starting point.

The brief involved suggesting three plants, each of a different habits (tall, bushy and spreading or trailing) that feature the chosen colour in either foliage or flowers. After some head scratching, the following scribble emerged.

My tall plant is the switchgrass Panicum virgatum, which grows to 1.2 metres, although younger plants in a container are less likely to achieve the full height. The glaucous grey leaves will give some relief to the otherwise monochrome scheme, with deep, metallic red flower heads in August.

Panicum virgatum 'Warrior'

The middle layer is the purple leaved Sedum 'Matrona', with its dense clusters of pink-white flowers.

Sedum 'Matrona'. Image © Crocus

The spreading plant is one of my favourite hardy cranesbills, the pale pink flowered Geranium 'Dusky Crug', again with deep, maroon foliage.

Geranium 'Dusky Crug'

Relatively low maintenance, with minimal deadheading required, all three choices will prefer a free-draining compost, none being voraciously hungry (the sedum in particular has a tendency to become floppy with too rich a medium); neither watering nor feeding need be too onerous a task – depending on conditions, you could water when the compost begins to feel dry (perhaps once a week) and feed once a month.

I’m fond of this combination, but aware that it’s not perhaps quite in the spirit of the brief, reaching its peak in August and September – a pot for late summer and early autumn. If I’m to bring the season of interest forward into early summer, I could stretch the colour theme a little, to embrace deep red stems and foliage and/or crimson flowers. Then we could try a combination built around Lobelia cardinalis 'Queen Victoria', with Heuchera 'Autumn Leaves' occupying the middle layer, above the trailing deep green foliage and of Pelargonium 'Mexican Beauty' this would work well in partial shade, and although the lobelia would be the last to come into flower (August again), there would be plenty of interest throughout the period with the deep maroon of the stems, over the vibrant shades of the heuchera foliage (softened slightly by the white flowers from June) and the longer flowering period of the ivy-leaved pelargonium.

The pelargonium would need to be included in my regular picking-over regime in order to keep it in flower, and a weekly high potash feed would help. Watering needs to take into account that the loblia favours damper conditions than the pelargonium, while the heuchera isn’t too bothered. Which sounds like a faff, but a can minus the rose, or the similar setting on a decent hose attachment, would make it perfectly possible to direct the majority of the water towards the centre of the pot. A good dousing, every other day, unless exceedingly warm or windy.

My imaginary courtyard pot display is now looking rather flamenco-inspired, with this container situated in a slightly sunnier spot than the partially shaded area enjoyed by the panicum-sedum-geranium combo, along with pots full of Dahlia 'Bishop of Llandaff', Cosmos atrosanguineus, Aeonium 'Schwartzkopf' and Ricinus communis 'Carmencita'. With plenty of green in between, and a large jug of sangria.

With thanks to Crocus and Fibrex Nurseries for the use of images.