RHS Journals

The Garden
October 2002

Planting for the bleak midwinter

Winter need not be a dull time in gardens. RHS Gardeners Dean Pickett, Fiona Wilding, Andy Willocks and Chris White consider planting up containers to provide interest throughout winter and early spring

Images: Tim Sandall/Toplinc Imaging

For those lucky gardeners who have planned carefully for year-round colour, this is an exciting time of year. About now they will be sitting back and eagerly anticipating the onset of true winter – the bright red stems of a low-lit cornus against a cold, blue sky, or the sweet citrus scent of a witch hazel planted near the back door. But for many gardeners, winter can be grim. As summer fades into late autumn, brown twigs and bare soil all too often make gardens bleak and uninviting.
To help plug this gap, we asked gardeners from each of the RHS gardens to produce a recipe for two winter containers. All can be planted up now and will provide colour, texture, and in some cases scent, through the darkest months. The gardeners have mixed winter favourites with more unusual plants that can be transferred into the open garden when they outgrow their pots. Many of these use a backbone of evergreens, which allows spring-, summer- or autumn-interest pots to be created with the addition of a few seasonally colourful flowering plants. It could be the start of future forward planning.

Dean Peckett Senior Supervisor, Floral Ornamental Department, RHS Garden Wisley

When planning a container display think about what will catch your eye in winter. Subtle combinations of foliage can bring a container to life; anticipate the extra glamour given by frost to the stems of an evergreen shrub or an ornamental grass.

In our first container, which measured 58cm across by 60cm deep (23 x 24in), we used contrasting foliage colours and shapes. Abies procera 'Glauca Prostrata' combined with Nandina domestica (not fully hardy); Stipa tenuissima provided a striking architectural contrast.

In addition Cornus sericea 'Cardinal' provided winter-stem colour. Helleborus argutifolius 'Silver Lace', with its bold silver-and-green foliage, looked good against the rich purple leaves of Heuchera 'Regina'. Underplanting with a large white crocus such as Crocus vernus subsp. albiflorus 'Jeanne d'Arc' would add early spring interest.

In the second container (60cm across by 38cm deep/24 x15in) we chose a red-and-brown colour theme. It was dominated by the purple leaves of Heuchera 'Regina' topped by the long-lasting white flowers of Skimmia japonica 'Rubella'.

Behind them the dark, evergreen leaves of Drimys lanceolata added height and bunches of creamy yellow flowers: not fully hardy, this might need protection from severe frosts.
Contrasting foliage shapes were added by a fern, Polystichum munitum, spiral-leaved rush Juncus 'Unicorn' and golden Erica lusitanica 'George Hunt'. Red tulips added a splash of colour.
We used a multipurpose compost and put plenty of crocks and gravel in the bottom of the pots to ensure that they didn’t get waterlogged over the winter months. John Innes No 2 compost would also be suitable. Little irrigation is required over winter and no feeding, as the plants are not in active growth. Lightly water during dry spells if required.
When underplanting containers with bulbs position them carefully in between the other plants, at twice their own depth, one bulb-width apart. To give a colourful display over a prolonged period, select two bulbs which flower at different times and plant in the same spot but at different depths. For instance, tulips can go below earlier-flowering crocus.
There are many variations on this foliage-dominated container. Viburnum tinus, Camellia x williamsii 'Donation', Sarcococca hookeriana var. humilis and cultivars of Erica can all be underplanted with winter bedding plants for a succession of winter interest.

Fiona Wilding Senior Gardener, Decorative and Nursery, RHS Garden Rosemoor

October signals a time for change at RHS Garden Rosemoor as the first frosts catch the summer bedding and seasonal plantings. As the summer bedding is replaced by winter and spring plantings, containers are also given a new lease of life.

Our smaller barrel (45cm wide x 30cm deep/12 x 18in) was planted up with a golden theme. Euonymus fortunei Blondy ('Interbolwi'), a golden variegated holly and Choisya ternata 'Sundance' are all evergreen shrubs. An ivy, Hedera helix 'Goldchild' and a sedge, Carex dolichostachya 'Kaga-nishiki', added different textures.

These were interplanted with Narcissus cultivars to flower in succession: 'Little Witch' and 'Tête-à-Tête' flowered in February followed by 'Jack Snipe' and 'Jumblie' in March, and 'Hawera' in April and May. Primula 'Crescendo Lemon' flowers through winter and spring if regularly deadheaded.

The larger container was 60cm wide by 45cm deep (24 x 18in). We filled this with ericaceous (lime-free) compost, and planted a purple, orange and red theme. Red stems of Cornus sanguinea 'Midwinter Fire' and scarlet berries of acid-loving Gaultheria procumbens persist throughout winter. Similarly intolerant of lime, Pieris japonica 'Mountain Fire' and Leucothoe Scarletta ('Zeblid') have leaves that colour up as the weather cools down, while evergreen Pittosporum tenuifolium 'Tom Thumb' has beautiful purple foliage all year round.

Uncinia rubra and Phormium 'Maori Sunrise' contributed different grassy textures to the scheme, and a variety of bulbs added colour in April and May.

Andy Willocks Nurseryman, RHS Garden Harlow Carr

Compared with planting summer containers, when a wealth of choice flowering plants is available, winter is a challenge. In our Yorkshire climate, durable evergreen plants have to dominate containers as the plants need to look good even after extreme weather conditions. With this in mind, I looked to plants already growing well at RHS Garden Harlow Carr.

For their tolerance of bad weather I chose Juniperus squamata 'Blue Carpet' and Abies concolor 'Compacta' with its attractive blue-bloomed needles. They provided the structure for a blue-and-silver colour-themed, 38 x 38cm (15 x 15in) container and variation in textures and shapes. Lavandula angustifolia 'Munstead' was just in flower in October, but I chose it for its bluish-silver leaves, which give it all-year-round appeal, and its scent.

I used Pittosporum tenuifolium 'Silver Queen' as it also performs well at Harlow Carr, despite a reputation for tenderness. If in doubt, keep it in a sheltered spot.
Dwarf hebes are great for winter containers as there is so much variation of leaf size and shape. Plants were chosen from those performing well in the trial hebes in the garden.
Hebe albicans 'Snow Cover' has a low growth habit, making it ideal to grow over and soften the edges of containers. It with-stands the hardest of winters and is noted for its pointed short, stout, almost white leaves. Hebe recurva also does well and its slender curved leaves brought an alternative form to the container.
Iris 'Harmony' gave colour from early March to the end of April; a variegated ivy was planted to cascade over the front edge of the pot.

The second container (50 x 50cm/20 x 20in) featured a mixture of colours. The main plant was Leucothoe fontanesiana 'Rainbow' with extraordinary, multicoloured, evergreen foliage and attractive, bell-like flowers from late February to May. It needs lime-free soil. Unfortunately its new foliage is susceptible to frost damage in early spring, but this soon clears up after regrowth.

Two good groundcover plants were added - a silver- variegated Vinca major (greater periwinkle - rather vigorous but easily trimmed back) and Euonymus fortunei 'Emerald 'n' Gold'. Periwinkles flower all through the year. Dwarf Erysimum cheiri (wallflower) produces a wealth of scented flowers and was planted at the front of the container to avoid it being swamped by more vigorous plants. Hebe 'Pinocchio' was included as a finishing touch.

Chris White Senior Supervisor, Hill Top Garden, RHS Garden Hyde Hall

We planted a large terracotta pot with a yellow theme and a basket with a white theme, and tried to use as many plants as possible that could be planted out into a normal garden setting once they had outgrown their containers. We also wanted the pots to make a good container display for at least two winters, given occasional pruning.
Lots of evergreens and foliage plants were included, which could then be enlivened with bedding plants and bulbs at other times of the year.
Because the frost-proof terracotta pot was so large (70cm across by 65cm deep/ 27 x 25in) and heavy, it was moved to its final position before planting up. Crocks were laid at the base to provide good drainage, and then the container was filled with a gritty, loam-based compost with a handful of slow-release fertiliser mixed in. The fertiliser already included in the compost would have been sufficient for plants that are only in the container for winter, as the plants are not actively growing at this time, but we wanted our containers to last for a couple of seasons.
The same basic materials were used in the basket, which was easier to move thanks to its two handles. Because of this, slightly tender plants could be incorporated as the container could be transferred to a more sheltered position during inclement weather. It was lined with plastic to prevent the wicker from rotting away and a proportion of ericaceous compost was added to the mix to keep the lime-hating plants happy.

For the white colour-themed basket (65 x 50cm/19 x 25in) the main focus was a large specimen of Osmanthus heterophyllus 'Variegatus'. In front of this were planted two dwarf Pieris japonica 'Prelude' and some Calluna vulgaris 'Golden Turret', which has attractive golden foliage with white flowers to follow. Narcissus 'Minnow', used in this arrangement, proved more successful than the N. 'February Gold' chosen for the terracotta pot.

For a little extra interest, white winter-flowering pansies were used to fill any gaps. They can be removed after flowering, when annual summer bedding can prolong the season.

In the terracotta pot, Cupressus macrocarpa 'Goldcrest' was a good shape and colour for the back. It increased the height of the planting significantly, with a Euonymus japonicus 'Aureus' to either side. Although quite small to start with, these gradually grew to fill out the middle section.

This was just as well because the Milium effusum 'Aureum' (Bowles' golden grass) which was meant to fill this area failed to thrive until much later in the year. At the front we positioned several plants of Calluna vulgaris 'Golden Turret'. Two yellow-variegated ivies were planted to trail down the front.
Finally, groups of Narcissus 'February Gold' bulbs were set between the shrubs. Once they started flowering they proved too tall at 30cm (12in) and did not fit in with the rest of the planting. Their foliage had to be cut back after flowering for tidiness; this weakens the bulbs so is only recommended if they are to be discarded after one season.

Choosing the right container

The containers used at Rosemoor were chosen to fit in with their surroundings. The two wooden half-barrels are often used in the cottage and shade gardens, as both contain wooden structures.
Wooden containers benefit from a plastic liner to prevent them from rotting. The Rosemoor tubs were lined with old plastic from the polytunnels, but offcuts of pond liner, strong binbags or compost bags work just as well. After planting, the liner was trimmed off just below soil level so it did not show. Wooden containers should also be raised off the ground on bricks or pot feet to prevent them from rotting at the base.
Fibreglass and plastic containers dry out more slowly in hot weather, so are ideal for summer use, but they give delicate roots less frost protection than wood does.

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