Garden for long enough and you eventually come to the inevitable realisation that for several perfectly good reasons it’s not that easy to create a memorably good winter pot display. Why not? First and foremost is the fact that unlike its summer equivalent (a completely different creature) you can’t simply stuff a winter container full of lots of frothy annuals, heat-loving, dramatic foliage plants, gauzy grasses, and showy, frost-tender perennials and then hope for the best. Instead the planting must be chosen to be resilient in the face of cold winter winds, heavy rain and frost, as well as tolerant of short days and low light levels, while somehow still being decorative enough to justify its prime position for up to six months. It’s quite the ask.
Add to this the almost non-existent growth levels during the cold, dark months of winter and very early spring – an often overlooked factor when it comes to creating that all-important sense of abundance – and you can see why so many gardeners decide to throw in the towel. And yet a lush and artfully-planted winter pot is exactly what’s needed during these cold, dark, wet months when it can feel like summer is a million light years away.
How to get it right? Let’s start with the container itself, which should be generously and elegantly proportioned (or as a friend described it, a pot with poise), and made of a handsome, durable, frost-proof material that won’t fade, discolour, crack or shatter. As regards size, I’d suggest a minimum height and width of 60cm. Big is best for many reasons, not least of which is that the larger the pot the greater the protection it gives plants’ vulnerable root systems from exposure to winter frosts and even periods of winter drought.
That said, winter wet kills far more plants in this country than winter cold or drought, so for obvious reasons drainage holes at the base are also a must. Even then winter pots can still suffer from waterlogging so it’s always a good idea to gently raise them off the ground using either bricks or what are known as “pot feet” beneath the base. These will also help to protect the containers themselves from frost damage and the plants growing in them from slug and snail damage.
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As regards the best growing medium, avoid using garden soil or a peat-based compost and instead use a good quality free-draining, loam-based John Innes compost, which is available from most good garden centres. Many gardeners also like to place either small, flattish stones or pieces of broken crockery (known as “crocks”) over the individual drainage holes before filling the container with compost on the basis that these prevent the holes from becoming clogged as well as to stop leaching of the compost. While more recent research suggests that this isn’t strictly necessary I still do so on the basis that it makes sense. But just take care not to overdo it, all you need are a few.
My next tip is put your pot in its final position before filling it otherwise it can often become too heavy and unwieldy to easily move. To encourage the best display possible try to choose as sheltered and bright a spot as you can, where your container is protected from the worst of winter gales and harsh frosts. Use a John Innes-based compost to fill it, working some generous handfuls of horticultural grit or horticultural-grade vermiculite into it (this will also help with drainage) and gently firming it down as you go. Stop when the compost level has reached about 25cm below the rim, at which point you can start positioning your plants (planting them much more closely than you would in the ground) and then backfill with compost to within 5cm of the rim.
But which plants? Ideally these should be hardy and evergreen, with a visually interesting mixture of foliage shapes and growth habits including some that are strongly architectural. For example, trailing ivies planted around the sides of a container will soften its hard edges and give depth to the planting, while combining these with a compact evergreen grass, some hellebores and a specimen dwarf conifer will provide a pleasing contrast in terms of their more upright, vertical growth habits and foliage shapes.
All winter containers should include at least one largish stand-out evergreen plant chosen for its star presence. This could be a dwarf or slow-growing species of conifer as mentioned above including varieties of the dwarf mountain pine (Pinus mugo); Japanese maki (Podocarpus macrophyllus); varieties of the Eastern white pine (Pinus Strobus ‘Tiny Kurls’, Pinus strobus ‘Sea Urchin’ and Pinus strobus ‘Green Twist’); or Japanese cedar (Cryptomeria japonica ‘Bandai-sugi’), many of which are also suitable for training as bonsai specimens.
Dwarf conifers aside, other species of evergreen trees, shrub and sub-shrubs suitable for making a statement when used as young plants in a large winter container display include Pittosporum tobira ‘Variegata’; varieties of the statuesque spurge known as Euphorbia wulfenii; the variegated Fatsia japonica ‘Spider Web ’and its finer-leafed relative Fatsia polycarpa; bay (Laurus nobilis); the grass-like Libertia chilensis; many kinds of skimmia including Skimmia ‘Fragrant Cloud’ (great for its perfume as well as its evergreen presence), Skimmia ‘Kew Green’ and Skimmia ‘Rubella’, varieties of scented winterbox including Sarcococca ‘Winter Gem’; and evergreen species of true grasses including Chionochloa rubra, Anemanthele lessoniana, Carex testacea and Carex ‘Irish Green’. Various varieties of the grass-like Astelia including the silver-bronze leaved Astelia nervosa and the silver white Atelia ‘Silver Shadow’ can also be grown in a largish winter container.
Other winter-hardy decorative evergreens or semi-evergreens that are a great choice for a winter container and will combine well with the above include Lenten hellebores (Helleborus x hybridus); the Corsican hellebore (Helleborus argutifolius); varieties of coral bells (Heuchera and x Heucherella); the silver-leaved Senecio candidans ‘Angel Wings’; and ferns such as the Japanese shield fern (Dryopteris erythrosora); the soft shield fern (Polystichum setiferum Plumosomultilobum Group); and the dwarf holly fern, Cyrtomium fortunei ‘Clivicola’.
There’s also still time (but hurry) to add some colourful seasonal fireworks to your winter pots by underplanting with a lower layer of late winter and spring flowering bulbs such as snowdrops, winter aconites, cyclamen, scilla, Iris reticulata, muscari, crocus and dwarf narcissi. Some hardy winter bedding plants such as winter pansies, viola, polyanthus and primulas will also add a flash of colour. In this way you can enjoy the very best of both worlds with a display that has real staying power but still rings in the seasonal changes with style.
This week in the garden
- The very heavy rainfall of recent weeks has resulted in badly waterlogged soil in many parts of the country. If this is the case in your garden or allotment then wait until ground conditions improve before carrying out traditional late autumn tasks such as dividing perennials, planting spring-flowering bulbs, and planting bare-root plants. Otherwise you run the risk of causing serious damage to the soil, resulting in compaction, poor drainage and poor plant health.
- Late October-November, as flowering comes to an end and the plants enter winter hibernation, is a good time to prune rambling and climbing roses and tie in their lax stems before winter storms damage the plants. To help prevent common diseases such as blackspot from overwintering as fungal spores on the fallen leaves, collect, bag and then bin these before spreading a layer of organic mulch around the base of the plant.
Dates for your diary
- From Sunday, October 29th, until Sunday, November 12th, National Botanic Gardens Glasnevin, Dublin, Crainn na hÉireann, an exhibition of over 60 paintings produced over the last two years by members of the Irish Society of Botanical Artists as a celebration of the seasonal beauty of Ireland’s native trees, see irishbotanicalartists.ie
- Saturday, November 11th (9.45am-3.30pm), RHSI Bellefield Gardens, Shinrone, Co Offaly. R42 NW82, Gardening for the Future, a practical one-day workshop on soil life and structure, composting methods, organic feeds and new ways of gardening, see rhsi.ie for booking details