Best Container Plants For Frosty Patios And Balconies

Why Containers Struggle When The Frost Bites

Roots in a pot have nowhere to hide. Where soil in a border stays a degree or two above freezing thanks to the sheer bulk of the ground around it, compost in a container can freeze solid within a few hours of a hard frost. Add a biting east wind across a patio or a fourth-floor balcony and you have the two things that kill more pots than anything else: frozen roots and desiccation.

That is not to say a frosty patio has to look bleak from November to March. It simply means choosing plants that are genuinely hardy, giving them more room than you think they need, and paying attention to drainage. A few practical rules sit behind every tough container display:

• Go bigger than you would in summer — a 30cm pot or larger holds enough compost to buffer a cold night.
• Use frost-proof containers. Glazed stoneware, oak half-barrels and thick plastic all survive; thin terracotta often cracks.
• Stand pots on feet or bricks so water drains freely and the base is not sitting in a puddle of ice.
• Plant into a soil-based compost such as John Innes no. 3, mixed with a third horticultural grit for drainage.
• Ditch the saucer over winter. Trapped water is the quickest route to rotted roots.

Evergreens That Shrug Off A Cold Snap

Structure comes first. Without evergreen bones, a winter container is just a collection of dead stems waiting to be tidied. Fortunately there is a good range of compact shrubs that tolerate wind, cold and confined roots.

Skimmia japonica is close to ideal for a shady patio, holding glossy rosettes of leaves all year and producing tight buds that open fragrant in spring. Sarcococca confusa, or Christmas box, is quieter to look at but earns its place for scent alone — small white flowers in January that you can smell from the kitchen door. Euonymus fortunei in its variegated forms is almost unkillable in a pot and brightens the dullest corner. Dwarf hebes with small, tight leaves cope well with coastal and exposed sites, though they resent waterlogged compost.

For trailing interest, Vinca minor spills over the rim and flowers sporadically in mild spells, while evergreen grasses such as Carex oshimensis add movement without needing much root space. Keep them trimmed, not sheared, in early spring.

Winter-Flowering Heathers And Small Gems

Nothing lifts a grey January quite like winter heather. Erica carnea flowers from December into March in shades of white, pink and deep magenta, and it is properly hardy — far tougher in a pot than its summer-flowering cousins. The one thing it insists on is ericaceous compost, since it will sulk in limey soil-based mixes. Top-dress with the same compost each spring rather than feeding.

Pair heathers with a few smaller treasures that earn their keep when little else is doing much:

• Helleborus niger, the Christmas rose, for nodding white flowers from a sheltered pot.
• Galanthus and Cyclamen coum, planted as bulbs or small corms in late summer and left undisturbed.
• Ajuga reptans in a bronze-leaved form, filling gaps under taller shrubs.
• A tight clump of Festuca glauca for silver-blue contrast, provided drainage is sharp.

Bulbs And Fillers For A Seasonal Swap

The cleverest container gardeners treat winter as a relay race rather than a single planting. Layer spring bulbs beneath your evergreen shrubs in autumn: Narcissus and crocus at the base, tulips above them, and a shallow scattering of snowdrops near the surface. The shrubs hide the bare compost while the bulbs are dormant, and the flowers push up through them in February and March.

Hardy winter violas and pansies make useful gap-fillers, but plant them in a separate pot if you can. Their tendency to flop and rot in a wet January is much easier to manage when you are not risking a shrub you have grown for three years.

Care Through The Cold Months

Winter container care is mostly about water and wind. Evergreens keep losing moisture through their leaves, and a dry, freezing wind can scorch them badly, so check the compost every fortnight and water on any mild, frost-free morning — even in January. Soggy is far worse than dry, though, so never water if the compost is already damp.

Group pots together against a sheltered wall to share warmth and reduce wind exposure, and wrap the outside of terracotta or ceramic pots in bubble wrap or hessian if a severe spell is forecast. Raise them onto feet, check drainage holes are clear, and top-dress with grit to keep the surface dry and stop weeds. Stop feeding altogether until growth restarts in March, and hold off pruning until the worst of the cold has passed — dead stems protect the crown beneath them.

Making Room For Wildlife On A Frosty Balcony

A cold patio can be one of the best places to help garden birds and insects through the lean months. Berry-bearing shrubs such as Sarcococca and female Skimmia provide food, while seed heads left standing on grasses and Echinacea offer a late larder for goldfinches and sparrows. Ivy on a nearby wall is one of the single best wildlife plants in the country, flowering late and fruiting in early spring.

Leave hollow stems and a small, undisturbed corner of pots where ladybirds and lacewings can shelter. Most importantly, keep a shallow dish of water topped up and thaw it on frosty mornings — birds need to drink and bathe even when the ground is frozen solid. A few well-chosen pots, tended kindly, will carry your patio through to spring and bring it to life while the rest of the garden sleeps.