Window boxes can add another dimension to container gardening; they can be planted with anything from perennials and shrubs for winter colour, to a dramatic summer display of tender plants such as trailing geraniums (Pelargoniums). However, you must ensure that your window box is securely fixed in place - containers full of moist compost and plants are heavy.

Prepare the Container

1. Make sure that your windowbox has drainage holes in the base or at the bottom of the sides. Some plastic containers may need to be drilled through.
2. Cover the holes with a 5-7 cm layer of stones or crocks, topped off with a piece of sacking, Plantex membrane or J cloth to stop the compost from being washed out.

Arrange the Plants

1. Consider how you want to arrange the plants; think about the view of the box from out of the window, as well as how it will look from the front.
2. Arrange plants in their pots on top of the compost, placing trailing plants around the edges so that they will eventually cover the box. The other plants should be spaced out so that they will fill the box as they grow.

Add the Compost

1. Use the pot of your largest plant to check the amount of compost you need to add to the window box.
2. Hold the pot inside the box, and add compost to the window box so that the top that the compost surface of the plant pot finishes about 3 cm below the rim of the box.

Add the Plants

1. Start by planting the plant with the tallest pot, easing it out of its pot and placing it into position.
2. Add more compost to get the correct planting height of smaller plants, making sure that they are level with the first, largest plant.
3. Ease plants out of their pots keeping their rootballs intact, and place them in the container.
4. Use handfuls of compost to fill in the spaces between the roots of each plant, firming them in as you go.

Water Regularly

1. When you have finished planting, water the window box well using the rose attachment on your watering can. This will ensure that the top layer of compost is not washed away from the roots of the plants.
2. Apply a layer of pebbles or gravel over the top of the compost to help to retain moisture around the plants.
3. Your window box will need to be watered regularly - daily in hot dry weather.