Evergreen
One of the first choices to make when thinking about what to put in your window box is whether you want something seasonal – bulbs and annuals that you change a couple of times a year – or more permanent. A mix of evergreens with flowers or berries planted in winter will bring warmth and comfort to cold, gloomy days.
- If evergreen shrubs outgrow their space, simply move to the garden or a larger container.
- Hebes interplanted with heathers and trailing ivy look subtle and stylish. In a container, ivy will behave itself better than in a border, and many types have lovely variegated leaves.
- Something tall, something trailing and something standout is a good general rule of thumb for window boxes.
Brights
A mix of contrasting colours catches the eye and shows off your personal taste. Start with your favourite colour, then add its opposite on the colour wheel. Here, blousy apricot begonias, sky blue petunias and pink and purple salvias clash and complement each other at the same time.
- Varying shape, size and colour makes the plants stand out. Repeating plants so that each side mirrors the other gives the box a more cohesive, thought-out feel.
- Soft petunias and begonias will happily bloom the whole summer long. Pink blackcurrant sage adds height, and tiny yellow santivalia make a brilliant carpet at the foot of the box.
- Coloured foliage can work just as well as flowers, especially a mix of contrasting light and dark leaves.
What to plant
- Flowers. Petunias, begonias and geraniums are traditional window box blooms because they’re low maintenance and provide continuous colour. Pansies are lovely flowers for the autumn, easy to care for and vibrant. Fuchsias are good for shady spots.
- Position. Think about the direction your window box will be facing. Planting a sun-loving plant in a north-facing box runs the risk of it becoming overly leggy as it reaches for more light. Equally, shade-loving plants can scorch in a container that faces south.
- Maintain. Regularly deadheading flowers will encourage new growth. Trim back leggy plants and keep an eye out for wilted leaves or pest damage so that problems can be tackled before they take hold.
Tip. Match the size of the box to the size of the plants. Compact plants are good for smaller boxes, while larger plants will need a larger box that holds more water.
Edible
Start small, choosing one or two herbs or vegetable plants that you use often in your cooking. Think about timings, as it may be possible to harvest one of the plants just as another begins to need more room. Mix a good slow-release fertiliser into the compost before you start planting.
- Herbs can be grown from seed in spring or plants at other times of the year. Basil, chives, dill and sage are all great herbs to start with.
- Salad leaves are simple to grow and can be sown all year round. Short, rounded carrots can be great for a box, as are dwarf peppers or even fruit, such as calamondins. Cherry cascade tomatoes will spill over the edge and make perfect bite-sized snacks.
- Most veggies and herbs need full sun, so set up your window box where it’ll get at least six hours of direct sun every day.
Growing in window boxes
- Soil. Boxes need drainage holes, so consider drilling a few in the bottom if there aren’t any. Most plants need a minimum soil depth of 30cm, and a soil-based compost such as John Innes will retain water better.
- Sunlight. There are plants for every situation, whether sunny, windy, shady and sheltered. Alpines and succulents are great for hot, windy spots – remember they’ll need a special soil, though; ferns and wildflowers will thrive in shade.
- Sustain. Plants that live in small spaces need love and attention. With such little soil, boxes can dry out quickly, which means regular watering (as soon as the top inch of soil feels dry) and feeding (once a week if possible).
Tip. Window boxes filled with soil, plants and water are heavy. Use proper brackets and the right wall plugs and screws.
Box materials
- Wood goes with almost any style, comes in a wide range of sizes and tends to be affordable. Hardwoods such as cedar or teak will be more durable than a softer pine, which can quickly rot.
- Terra cotta window boxes are made from unglazed earthenware and they’re usually more expensive. It’s a beautiful material, but can be prone to cracking in freezing temperatures – smaller planters could be brought inside during cold spells.
- Strong, durable and often lightweight, metal boxes might include aged zinc, aluminium, Corten or galvanised steel and even copper. Each of them can look stunning, but expect to pay for it. Keep an eye out for rust.
Tip. Be careful that the walls your window boxes sit on or are attached to aren’t exposed to too much water.