Tips on how to add some formality to your gardens with topiary - plus, find out what else needs doing in the garden this week.

By Hannah Stephenson

I have to admit it, I love formal gardens, those with a definite structure, sense of purpose and everything in its place.

Clipped box hedges, strong geometry using evergreens shaped carefully into balls and pyramids, evenly spaced in uniform lines or sections, can give a garden - front or back - a contemporary lift. Even a couple of box balls or standard bays in pots either side of your front door can give your home a grand entrance feel.

If you want to add some formality to your patio this summer as a backdrop or accompaniment to pots which are full of colourful blooms, topiary may be the answer.

Potted topiary can add emphasis to a garden design, for example, placing uniformly clipped globes along the edge of a path. Shaped plants are often used in formal settings but can also act as valuable exclamation marks in more informal schemes.

Among the plants easiest to shape to your requirements are box (Buxus sempervirens), sweet bay (Laurus nobilis), yew (Taxus baccata) and privet (Ligustrum delavayanum).

While slow-growing evergreens are the traditional topiary plants, you can use climbers to cover wire frames for a faster result.

So, where do you start if you want to have a go?

Beginners should start with a simple box ball or bay pyramid that has already been trained to shape and keep it that way by trimming it twice a year, in early summer and early autumn. Potted topiary also needs to be watered well in summer and protected from frost in winter, so it's best to place it near the house.

As your topiary grows, clip it very lightly every couple of months, taking off the tips of the shoots, to keep its natural shape while it grows and encourage branching, which will help thicken the shape.

Tools you will need are secateurs, small hand shears or one-handed 'sheep' shears. Secateurs should be used to shape larger-leaved plants including bay, holly and viburnum.

If you are trimming a ball or dome, stand above the plant, turning the shears upside down so that the shape of the blade follows the curve. Keep walking around and standing back to view the shape, making sure everything is even.

Most topiary is based around a wire framework. Young shoots are tied into the frame to create bushy growth, then sideshoots are tied into the framework and cut back regularly to maintain the shape.

If you have a little more time to create your own pyramid in a pot, choose a plant which looks like it will grow to roughly the right shape, plant it in the pot and place three bamboo canes made into a wigwam shape around it, tied with twine at the top. Tie any long shoots to the cane with twine to form the outer edges, then prune the plants to the 'pyramid' template to maintain the shape.

You should avoid shaping evergreens between the end of summer and mid to late spring, or the soft re-growth might not survive frosts.

For a quick fix, grow some plain green ivy over a wire topiary frame to create a traditional effect much quicker. Just plant the ivy around the rim of the pot and twine the trails around the wires of the frame. The leaves should hold the stems in place and you can snip off unwanted shoots once your frame is covered.

Suitable ivy with short joints includes Hedera helix 'Duckfoot' and 'Tres Coupe', which remain compact.

Remember that potted topiary can also be slotted into your flower border at any time of year to fill gaps and add interest, although in winter more elaborate shapes you may have created out of bent wire, from peacocks to teddy bears, will be a good talking point when there's nothing else on the patio.

Best of the bunch - Crocus These pint-sized bulbs herald the start of spring, providing cheery early colour to borders, patio pots and naturalised in grass. They look stunning planted in drifts of one variety, opening wide in the sunshine to attract pollinating insects, their seedheads carried low in the foliage.

They may look fragile, with their delicate flowers in shades from purple and pale lavender to yellow and white, but crocuses are surprisingly resilient and can be planted at any time in autumn or early winter providing they have been stored in a cool dark place. When the narrow, dark green leaves wither, you can mow over them as long as you don't cut the grass too short.

The smaller-flowered specie crocus, such as C. tommasinianus, look great under trees and can spread rapidly, especially on poor, free-draining soil.

The larger-flowered Dutch crocus, also work well naturalised in grass or gravel, although can be susceptible to weather damage, especially when the flowers are fully open. But they are ideal for pots and look particularly effective planted in one colour in a container and left on the patio as an early-spring taster.

Specie crocus provide early colour in pots with other bulbs and bedding. The small corms can be planted above later-flowering bulbs and won't interfere with emerging shoots.

Good enough to eat - Broad beans Good quality fresh broad beans are quite difficult to buy in the shops, but they are easy to grow, hardy and the dwarf varieties are free-standing, so it's worth having a go yourself.

Make an early sowing outdoors under cloches or garden fleece or in a coldframe in February or March.

Before sowing, rake in a general fertiliser, then sow the seeds in drills 5cm deep in rows with plants 20cm apart each way, sowing more than you need at each end so you can transplant any extras to fill in gaps.

The dwarf varieties won't need supporting, but tall varieties should be staked using lengths of string along each row secured by canes. They shouldn't need watering before the flowers appear, but hoe between plants to stop weeds competing for nutrients.

Once the flowers are forming, give the plants a good soak once a week. In June, when the plants are flowering, pinch out the top 10cm to encourage the pods to form.

The first crops should be ready in June if you sowed in February. Pick them when they are 5-8cm long and cook the pods hole. If you want to shell them, harvest when the beans have begun to show through the pod but before the scar on each shelled bean has become discoloured.

After harvesting, dig the plants into the soil to provide green manure. Longpods are the hardiest of the beans, producing slender pods with kidney-shaped beans inside, which are sown in autumn.

The second group is Windsors, for spring sowing, which have short fat pods containing flat, round beans which are said to have the best flavour.

Good Windsor varieties include 'Green Windsor' and 'White Windsor', while favourable longpod types include 'Aquadulce Claudia' and 'Red Epicure'.

Three ways to... Control pests on the veg patch 1. Early in the year, put a layer of garden fleece over young plants to protect them from flying insects such as aphids, carrot fly and cabbage white butterflies. In the summer, replace the fleece with very fine plastic netting, draped over hoops of stiff wire and weighed down at the edges.

2. Keep rabbits out by installing a barrier of chicken wire fencing 1m high above the ground and 30cm below the surface around the patch.

3. Protect young plants from surface slugs with rings cut from plastic bottles, cutting sections 10cm high and pushing them 2-3cm into the ground. Copper tape is also worth trying around small raised beds.

What to do this week :: Spike lawns with a fork to alleviate drainage problems and fill in holes with sharp sand.

:: Sow spinach while the soil is workable.

:: If further snow persists, continue to brush snow off branches to stop them buckling under the weight.

:: Lift, divide and replant clumps of rhubarb which need rejuvenating.

:: Prune winter jasmine as the flowers fade.

:: Add a top dressing of gravel or chippings to the rock garden to help drainage around plants.

:: Prick out and pot on sweet pea seedlings sown last month.

:: Continue to harvest winter veg such as Brussels sprouts, kale and spinach.

:: Sow early peas in a length of plastic guttering filled with compost and keep in a cold frame or greenhouse to germinate.

:: Apply a dose of rose fertiliser to create a greater resistance to disease and encourage healthier plants.

:: Transfer fuchsia cuttings taken in the autumn into 5cm (2in) pots, but avoid heavy watering until the root systems are fully established.

:: Continue to plant fruit trees and bushes if soil conditions are suitable. Otherwise heel the plants in or put them, still wrapped, into a frost-free shed until the soil conditions improve.