Design a window box

Choosing your plants

Many plants will thrive in a rectangular window box, but for an ever-changing display, try planting with a selection of permanent plants for year-round interest plus some annual flowers, which can be replaced as they fade. Most garden centres stock a good range of annuals, and although there are more varieties to choose from in spring and summer, you should have no problem finding plants to grow in autumn and over winter.

There's a huge range of plants that will do well in window boxes. To narrow down a selection, first take into account where it will be placed - is it sunny or shady, sheltered or exposed? High exposed situations have their own special problems as the wind sucks moisture from the air - look at plants adapted to dry conditions that minimise water loss from their leaves.

For summer planting schemes consider scented plants to send perfume into open windows. Or why not explore vegetables and herbs for a kitchen window box?

In design terms consider what effect you want - is it a mass of a single variety or a symmetrical structure? An easy rule of thumb is to use an odd number of plants, and think of planting in terms of triangles - something with an evergreen structure flanked by shorter flowers always works well, for example.

What to do

How to plant

• Measure your windowsill before buying a window box to make sure it will fit comfortably.
• Choose a container with drainage holes and cover them from the inside with a layer made up of broken terracotta pots . Known as crocks, this layer prevents the drainage holes becoming clogged up with compost and the soil from falling out. Or you can use broken up polystyrene packaging.
• Fill the box with compost to the level of the bases of your largest pots - aim to leave a 2cm (0.7in) gap between the top of the compost and the rim of the pot.
• Then, with plants still in their pots, arrange them in the window box taking into account structure, foliage texture and colour. Make sure that taller plants are at the back and trailing plants at the front.
• Arrange plants, while still in their pots,
• When you're happy with the display, knock them out of their pots and put into position.
• Don't pack plants in too tightly as it creates ideal conditions for diseases to flourish. Fill in the gaps with compost, firm down and water.

Aftercare

• Place your window box on a deep ledge or fix to wall brackets.
• Water to keep just moist, usually once a day during summer and autumn.
• Give the plants a boost once a week when they're established by adding liquid fertiliser to a watering can.
• Keep plants tidy by removing yellowing leaves and deadheading spent flowers.

Five plants for a sunny spot

• Nasturtium - attractive leaves, edible flowers
• Petunia 'Marshmallow' - this cultivar has good all weather performance and large flowers but there are many other upright and trailing varieties to choose from
• Helichrysum petiolare - its silver-grey foliage is a lovely foil to bright flowers
• Ivy - try one of the more delicate variegated types
• Pelargonium - survives even on windswept highrise balconies

Five plants for a shady spot

• Busy Lizzies
• Fuchsia 'Marinka' - excellent in hanging baskets and containers
• Ferns
• Cyclamen - a winter staple
• Skimmia japonica - provides good all year round colour