gardening-pict2437by Dick Handscombe, gardener and gardening author living in Spain for 25 years.

Throughout Spain, window boxes are used to brighten up the facades of some otherwise drab houses and apartment blocks, but many beach-front apartment blocks, villages, towns and urbanisations remain bland even though window boxes are easy and inexpensive to install.

Well planted, they can be colourful throughout the year with the best looking like mini-gardens and tall houses and apartment blocks can be made to look like a ‘Hanging Gardens of Babylon’. With a community cooperation and spirit, tiers of window boxes on four storey village houses and even taller apartment blocks can create an amazing effect to the benefit of residents and passers-by, even during the winter months when most individual and communal gardens are not at their best .

Why Have Window Boxes?

Window boxes serve several purposes.

  1. To brighten up the outlook from windows and doors onto balconies and terraces.
  2. To provide a screen from prying eyes.
  3. To brighten up the appearance of a dwelling from outside, both from the garden and from the street. We have them on the north and west sides of the house. The other sides are full of colour without window boxes and in our microclimate, south facing window boxes would need watering daily during June, July and August.
  4. To give the appearance that the house or apartment is lived in. Walk past a few blocks of apartments, down a few traditional village streets or through a few estates and you will notice that the properties with window boxes stand out, especially if well looked after; unfortunately also if they are rarely tended.
  5. To brighten up dull courtyards by hanging boxes on the walls or standing on low walls.
  6. To brighten up the semi-shade under large trees, perhaps where you eat or siesta, by hanging window boxes directly from boughs or supported on hanging shelves.
  7. To create a vertical vegetable garden with mini-varieties in tiers of window boxes fixed to a terrace wall or the security doors opening onto an open uncovered terrace.
What Types Of Window Boxes Are Available?

Every year new and improved designs of terracotta, glass fibre, ceramic and plastic window boxes appear. Some have a self-watering reservoir that holds sufficient water for several weeks. This is very useful when you expect to be away for holidays or short breaks. If you are planting trailing plants, these will soon cover the front sides of the boxes, so save money and don’t invest unnecessarily in fancy designs.

What Can Be Planted In Window Boxes?

gardening-pict1546The most reliable flowering plants are as follows:

All year round: Zonal and trailing geraniums/pelargoniums, except in the heavy frost/snow belt where they need to be put in a cold frame or a greenhouse for the winter.

Spring, summer and autumn: Trailing petunias, portulacas, zonal and trailing geraniums/pelargoniums, carnations, felicia /agathaea and in the shade, fuchsias and busy lizzies.

Spring: Dwarf trailing sweet peas, verbena and freesias.

Autumn and winter: Heathers and pansies, especially above the frost line.

Winter: Cyclamens, poinsettias, stocks and bulbs such as hyacinths and daffodils.

Colour can also be provided by the fruit and foliage of plants.

Fruits – the fruits on mock pepper and mini pomegranate plants can look very attractive during the autumn once annuals are past their best.

Foliage – begonias, spider plant, variegated ivies, herbs – on the widow sill outside the kitchen – and dwarf conifers especially in semi-shaded situations.

Vegetables – plants like trailing tomatoes, dwarf peppers, collections of edible herbs and cut and come again salad leaves are all possible.

If you are an absentee gardener, restrict your window boxes to trailing geraniums/pelargoniums and drought resistant succulents and cacti. If your visits are very infrequent, we suggest you replant your window boxes as soon as you arrive for a stay and let them die off when you leave. In this case remove the boxes from your window sill or balcony to an invisible place while you are away.

Window Boxes Do Need Watering!
  1. The soil in window boxes needs to be kept constantly damp to get the best out of your plants. We suggest that you achieve this by ensuring that you fill the window box with a rich water-retaining but free-draining compost. Being waterlogged can be as bad as being too dry. Our solution is to use a 5:5:1 mix of good soil, homemade compost and sharp sand with a little water-retaining gel mixed into the bottom half of the compost.
  2. Water twice a week in the spring and once a week in the autumn and winter. In the summer you will need to increase watering. Window boxes in full sun may well need watering every day.
  3. Plant less thirsty plants.
  4. Mulch the top of the compost with volcanic ash, grit, or coloured stone chippings.

Remember that the roots of plants in window boxes have a relatively limited amount of soil in which to search for nutrients for growth and flower production. We suggest that you take a three stage approach to satisfying their needs. As already mentioned, ensure that you fill window boxes with a rich compost mix, then feed regularly; monthly in the autumn and winter and weekly in the spring and summer. A weak feed at this frequency is better than a strong feed at less frequent intervals to achieve a steady rather than stop-go development of the plants. Ensure that you use a balanced feed and not one too high in nitrogen. The latter can stimulate green growth in preference to flower buds and long lasting flowers. Also, fast growing green growth can be fleshy and weak, therefore susceptible to disease and pests. Change the compost every second winter.

Pruning and Deadheading.

gardening-pict2364Flowering plants will flower more continuously and for longer if you deadhead regularly. Also remove all dead leaves and ends as soon as they appear, to prevent the occurrence of fungal diseases. Naturally trim to shape to improve the overall appearance of your boxes, but don’t over trim cascading plants such as trailing petunias and geraniums. If you are on the front line of apartments and your window boxes get burnt by salt spray during heavy storms or gales, wash the plants copiously with water as soon as possible and remove any branches that become burnt as soon as damage appears.

Hopefully more houses and apartments will look more attractive when we pass by during the coming autumn and Christmas seasons. Best of luck with your plantings.

© Dick Handscombe