Planting Planting your container is the next big consideration, and here again, simplicity is the best option. You can plant a flowery profusion or in a contemporary style, favouring a more minimal look with a structural plant. Try to stay away from 'blob' shapes if a structured look is what you are after.
You can go for a permanent planting - box, bay trees, lavender and citrus are classics. For a winter container you need to use hardy plants, so consider plants that can tough it out on the terrace all winter long. Clipped shapes are very effective for winter when the light shows up shapes and the relative absence of colour in the garden makes architectural forms more telling. This is exactly why so many winter garden photos have clipped box or yew as their subject.
You don't have to stay with box for clipping. Holly is a plant that we don't often grow but it is ideal clipped and can be grown in a large container. Hebes are naturally beautiful regular shapes and you can enhance this with clipping. Wonderfully glossy green camellias, the sasanquas especially, can be clipped, and have fabulous winter flowers when you need them most. Viburnum tinus 'Eve Price' can be grown in a container, clipped into shape and will flower all winter long.
Hydrangeas are very effective in summer, whether you choose the traditional mop-head, Hydrangea paniculata grandiflora or the fascinating oak-leaved H. quercifolia. Evergreen azaleas are used widely in the southern USA as clipped shapes and standards, with the bonus of spring flowers. Sissinghurst, again, uses clipped standard Agyranthemums (daisies) flanking the seat at the head of the Moat Walk to make a formal statement.
Contemporary containers are best planted with architectural plants, those with a definite shape either naturally or as the result of clipping or training - colour and prettiness detract from the container's impact and the message gets muddled. They also work well with different foliage colours. As an alternative to green try silver foliage, such as astelias, silvery hebes, santolina, lavender, is wonderful where it catches the light.
You can use containers as a home for many tender subjects such as Xeromena callistemenon, the Poor Knights lily, orange or lemon trees, bouganvillea, vireyas and viresias, moving these undercover in winter and exchanging them for a tougher subject. For the plantaholic, pots will enable you to have more plants, even to literally stacking them in tall, medium and low-level containers. But be careful that you do not create a chaotic, messy look. Simplicity is the key and a large pot or a grouping of two or three large pots almost always looks better than a dozen or more small pots.
New Zealand natives
Some of our New Zealand natives are stunning in containers. Architectural phormiums and cordylines are classic container subjects overseas, but choose the phormium with care as in our climate these lusty plants can easily burst your pot wide open. Astelias, especially silvery A chathamica (sold as 'Silver Spear') has a bold architectural look to it. The invaluable hebes form wonderful shapes without the need for clipping; try H topiaria, silvery H. albicans, 'Emerald Green'or H. diosmifolia, from the many, many available. The Marlborough Rock Daisies, Pachystegia insignis and P. rufa both have bold foliage and make fascinating container subjects. Many native grasses bronze wonderfully in winter and make a dramatic, if sometimes shaggy, container planting.
Contain it Whether its midsummer or the flowers are fading, use containers as an integral part of your garden scheme and bring renewed focus into your garden. Enjoy the new emphasis containers bring in the garden as the colour fades, and the fresh impact of form and structure throughout the year. Try it and see how much fun you can have!
Perfect pairing- hostas in a large 'tank' container, Moss Green Garden, NZ
Practical Matters
Materials Terracotta and other porous materials will dry out quickly in summer, requiring a good watering regime. Choose pots for winter carefully- porous materials can easily shatter in the frost as they absorb moisture that freezes and expands, causing cracking or worse. Nothing is more disconcerting to waking to a fine, frosty morning and a precious pot in pieces. Placing your plants in plastic inside your very special pot helps to keep the outer pot wall dry (porous material suck moisture from the potting soil).
Plant Space Fit the plant to the pot. Make sure that the plant has adequate root space and good soil or it will quickly become pot-bound and starved.
Drainage Most plants do not like to be in cold wet soil, in winter especially, sodden potting soil can freeze a plant to death overnight. Lift your pots off the ground in winter, even standing them on their upturned saucers to lift them above frozen surfaces and improve drainage. Pieces of an old broken clay pot in the bottom of your container are the classic solution to improve drainage. Failing this, largish, washed stones or very coarse gravel will work
Wind Make sure the plant is not top-heavy. Tall or large plants that can become a huge sail in winter winds and easily topple; this is not good for the plant and is potentially disastrous for your containers. Use heavier pots, site pots away from draughts, avoid corners where the wind whistles by and, as a last resort, surround them with sandbags to weight them down.
Water Don't forget to water your pots. In summer pots need watering regularly, sometimes daily. Wind is very drying and winter temperatures do not mean that plants need never be watered. Check the moisture in the potting soil regularly and water accordingly. Try to water in the morning so that any excess water has drained away before the temperature drops below freezing overnight.
Freezing Remember that plants in containers are more vulnerable to freezing than those in the ground. In severe climates choose carefully and place containers near the house or in a sheltered corner if you have concerns about plant hardiness. You can insulate the pot with bubble wrap but this spoils the look a little; a container in a puffa jacket is not what you are after.
