Sue Whigham gives her guidance for container planting success

Last year I ordered a salvia collection from one of the national newspapers. The plants arrived but they really were miniscule and looking unlikely to survive until the end of the week, let alone through to the next spring. I was then sent a replacement pack and now the greenhouse is full of salvias growing on quite well, despite there being a few mortalities. 

So I think this year that some of the shrubby varieties might like to be popped into a pot or window box with, say, lavenders and perhaps something like that particularly wonderful silver leaved plectranthus, Plectranthus argentatus ‘Silver Shield’ which I’m looking out for right now. The whole combination would produce a container that would need little attention throughout the summer as each of these plants love sunshine and are perfectly adapted for it. The soft, furry leaves of this Australian plectranthus are a case in point. It’s a vigorous plant but you can occasionally pinch it out and easily make new plants with the cuttings. It’s not hardy but then you could keep a few young plants in a porch, greenhouse or your house to overwinter and start off with more material for your containers the following year. 

It seems that you have to be quick buying plants this year as, if they are remotely desirable, they are selling out as soon as they reach the plant nurseries. I was talking to the proprietor of a local, family owned nursery not far from here the other day where, luckily for them, most of the plants they supply are home grown, and he suggested that “if you see it, buy it” as it is becoming difficult to keep up with demand. This is due to a combination of this past ‘Covid’ year with the new enthusiasm for all things horticultural and of course Brexit with new rules and regulations making it complicated for Continental suppliers to come over with ease and with their lorries full of lovely shrubs. (I remember the excitement at Merriments in the days when Dutch Dave arrived with his pantechnicon bursting at the seams with treasures).Perhaps the new system will settle down or British growers will eventually fill the gap. Either would be good, wouldn’t it? 

So to window boxes and containers. First find your container. As you already know, containers can be made out of just about anything but I suppose you would have to consider weight if you are planting up window boxes as you don’t want the sill to collapse under your newly planted up arrangement. Fibreglass containers weigh next to nothing and are useful for window ledges.

Marigolds have such a long flowering season and you can use them to enliven a salad

To be honest you can use just about anything. I have a particular yen at the moment for anything galvanised but there’s terracotta, stone, old coppers, old olive oil containers, apple crates and just about anything else. Try reclamation centres or markets like Faversham Market, which I gather is opening up again in July. Or antique centres selling garden ephemera. This part of the country is rather good for these.

Basically you can plant into any container provided it has drainage holes. Another starting point is to consider the architectural aspects of your property. A rustic cottage lends itself to weathered wooden troughs and old coppers (if you can find them) and perhaps terracotta pots look better with a backdrop of warm brick walls. If you run a bit short of good looking containers, you can always keep some plants in good sized black plastic pots and keep them at the back of a group of containers. The black pots do tend to ‘disappear’ when surrounded by foliage. I do that with dahlias so that I can move them around throughout the summer.  

So what about planting up an edible container. Perhaps fill one with herbs that you use on a regular basis. Basils come in the most lovely colours and flavours. Maybe have a pot full of marigolds (Calendula officinalis) with nasturtiums and borage thrown in for good measure. They all have such a long flowering season and you can use them all to enliven a salad. Chiltern Seeds offer an ‘old favourite’ marigold called ‘Radio’ which in 1931 was described as ‘New – a deep orange variety with quilled florets.’ After the war a packet of seed might have cost you 2d. The pollinators won’t know which way to turn with this combination of plants. 

Or take inspiration from Delos, the new garden at Sissinghurst. Commissioned by the National Trust and designed by Dan Pearson, this planting and landscape is inspired by Vita Sackville West and Harold Nicholson’s love of Delos in Greece. The garden is now open to the public and planted up with Mediterranean plants. Now that the plants are bedded in, they will not be watered again except, of course by rainwater. If you use a well drained gritty mix in a container you could fill a container with sun-loving succulents like sedums, saxifrage, and all manner of grey-leaved treasures. To prevent the soil from drying out completely a top dressing of grit interspersed with a few interesting pebbles works well.

I have a particular yen at the moment for anything galvanised. Try reclamation centres or markets or antique centres selling garden ephemera. 

A lovely, long flowering combination that the bees and other pollinators would relish would be perhaps a pink lavender such as L. ‘Felice’, grown with blue scabious; something like Scabious ‘Blue Diamonds’ and a perennial salvia such as Salvia ‘Sensation Deep Rose’ to give the whole display a bit of body. Or that scrumptious Salvia coccinea ‘Summer Jewels Lavender’ whose smoky lavender blue flowers go on from May to November. 

Don’t bother stuffing your containers with umpteen different plants. Keep things simple and stick to, say, three varieties. Vary the heights and don’t worry if they don’t all produce constant flowers. Beautiful foliage and form is just as gorgeous. I did see a winter container being planted up on the TV recently and particularly loved their use of epimediums (it was for a shady area) as their leaves are so exquisitely beautiful that it wouldn’t really matter if they didn’t flower. But as they do, that’s a bonus. 

Grasses add movement and texture to window boxes and containers. Grow blue sea hollies with perennial grasses – as the season progresses you will be left with lovely seed heads floating through the grasses’ foliage.

And finally, an artist friend of mine suggested that if she was planting out a window box she’d collect ephemera from the countryside and beach and put it together. Perhaps you could look out for discarded feathers, lichen and moss, old birds’ nests, pebbles, bleached driftwood and all manner of seed heads collected in the autumn such as teasels as well as shells and bits of this and that. She suggested popping a ‘bee hotel’ into the mix, plus adding a planting of a few long lasting bee-friendly flowers like the pot marigolds, to make it all look bold and individual and useful too. Actually, you could vary these if you keep the marigolds in individual pots and then replace them with something else in full flower and at their peak. I think that this idea would look marvellous in an urban setting and would certainly slow down the traffic!

Sue Whigham can be contacted on 07810 457948 for gardening advice and help in the sourcing and supply of interesting garden plants. 

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