Choose & plant windowboxes & troughs

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Last updated March 2018

Window boxes for all year round, or spring and summer, are great for instant decoration, especially when you’re too busy to garden. We tell you more about which plants to choose and how to care for them.

Advantages of windowboxes and troutomatghs
Types of windowbox and troughs
Siting and fitting a windowbox
Planting windowboxes and troughs
Plant care – in windowboxes and troughs
Planting ideas – evergreens for permanent plachernting in windowboxes and troughs
Planting ideas for summer windowboxes and troughs
Planting ideas – crops for windowboxes and troughs in the sun
Planting ideas – ‘wild’ flowers for windowboxes and troughs

Advantages of windowboxes and troughs

Windowboxes are the saving grace of many a house and garden, especially when you’re too busy to do much else. And if you are in the throes of building work, they’re probably the only thing you can do. Whatever the state of the surrounding land, they provide some semblance of a garden with a cheering view from indoors and out. The plants are well out of the way of builder’s big feet, and can be removed quickly and easily if you need to do work to the window.

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Types of windowbox and troughs

  • Ready-made – numerous designs, sizes and materials, including wood, metal, plastic and stone.
  • Home-made – make a made-to-measure box from timber or marine plywood. Or make a brickwork trough for the base of the house.

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Siting and fitting a windowbox

  • removable box is best for access to the window and ledge for repairs and maintenance.
  • Although boxes are heavy and unlikely to be blown away, fix them in place with side brackets or chains if they’re on the first floor or higher, for peace of mind.
  • For sills that slope dramatically, use wedges (home-made or bought) to keep the box on the level.
  • To allow windows to open outwards, support a box beneath the windowledge with right-angled metal or wooden brackets. Simply drill and plug holes in the wall in order to screw the brackets in position, using a spirit level to ensure that they are correctly placed.
  • Or choose a windowbox designed to be suspended  from screw heads projecting from the wall. Only suitable for small lightweight plastic boxes, but a row of these beneath a wide window is just as effective as one large container, and easier to lift and move.

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Planting windowboxes and troughs

  • Put plants in their pots inside the box or trough. Then they’re easy to whisk out – for house maintenance or to swap plants. If you want to disguise the pots, prefill the box or trough with compost and plunge the pots so the rims are covered. Or put the pots in first, then fill the spaces and cover the rims with bark mulch or stone chippings (heavier).
  • Alternatively, fill the box with compost and plant directly into it.

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Plant care – in windowboxes and troughs

Plants in boxes and troughs need more care than garden plants – there’s only a tiny volume of compost to hold in moisture in dry spells and warmth in cold weather.

Watering:

Drainage and insulation:

  • Waterlogged compost suffocates the roots and will kill them eventually.
  • Waterlogged compost will freeze solid during frosty weather and kill the plants.
  • Add drainage holes if not already there.
  • Insulate winter boxes and troughs. Line the boxes or pack around the pots with bubble plastic or polystyrene packing chips, disguised with a surface layer of compost, cocoa shell or bark mulch.

Feeding and other care:

  • The fertiliser content of composts is soon exhausted.
  • Feed with a suitable fertiliser from Thompson and Morgan. If you can’t decide which type to choose, then a tomato fertiliser is generally useful for flowering and fruiting plants.
  • Deadhead for more flowers.
  • Pinch out growing tips for bushy growth.
  • For permanent plantings, trim trailers in spring if getting straggly, and in summer to keep in check.
  • For permanent plantings, shear shrubs in summer to keep compact.

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6. Planting ideas – evergreens for permanent planting in windowboxes and troughs

Bushy plants:

For sun or shade:
Skimmia japonica ‘Rubella’ – red flower buds in late winter.
Euonymus fortunei, such as ‘Emerald and Gold’ or ‘Emerald Gaiety’ – small variegated leaves. Sun or partial shade.
Box (Buxus) – small glossy green or variegated leaves. Sun or shade.
Hebe – choose compact types. Smaller-leaved types are hardier. Sun or partial shade.
Piggy-back plant (Tolmiea menziesii). Leafy. Sun or partial shade. Prolific so you should be able to beg it from a friend or find it at a charity sale. If not, grow it from seed.

Trailing plants:

For sun or shade:
Creeping Jenny (Lysimachia nummularia) – green or golden-leaved form, yellow flowers. Prolific so you may be able to beg some from a friend, or find it at a charity sale.
Ivy (Hedera) – choose small leaved types.

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7. Planting ideas for summer windowboxes and troughs

Bushy flowering plants:

For sun:
French marigold (Tagetes) plug plants or seeds
Geranium (Pelargonium) plug plants or seeds.

For sun or shade:
Begonia plug plants or seeds.
Busy Lizzie (Impatiens).
Fuchsia.

Trailing flowering plants:

For sun:
Ivy-leaved geranium (Pelargonium peltatum).
Nasturtium – grow from seed. Not frost-resistant. Flowers edible.
Sweet pea (Lathyrus odoratus) – choose dwarf types that don’t require staking (grow from seed).

For sun or shade:
Creeping Jenny (Lysimachia nummularia) – green or golden-leaved form, yellow flowers. Prolific so you may be able to beg some from a friend, or find it at a charity sale.
Lobelia

Trailing leafy plants:

For sun:
Ground ivy (Glechoma hederacea) – a UK wildflower, but garden varieties are also available with variegated leaves i.e. G.hederacea ‘Variegata’ -sometimes referred to as Nepeta ‘Variegata’.
Helichrysum – grey-green leaves.

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8. Planting ideas – crops for windowboxes and troughs in the sun

Bushy plants:

Evergreen:
Thyme plants or seed – evergreen but can look scruffy in winter if not trimmed.
Sage plants or seed – evergreen but can look scruffy in winter if not trimmed.
Marjoram plants and seed – evergreen.
Rosemary plants or seed – evergreen, may be killed by hard winter. Dislikes being moved.

Perennial but die down each winter:
Chives – die back every winter

Annuals – grow from seed:
Parsley – grow from seed and replace each spring.
Patio vegetables – grow from seed.
Radishes – grow from seed.
Spring onions – grow from seed.

Trailing plants:

Strawberry plants give a wide choice. Those types without vigorous or any runners make compact plants for containers. e.g.alpine strawberry plants or seeds.

Cherry tomato plants or seed give a choice of crop to tumble over the edge of your container.

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9. Planting ideas – ‘wild’ flowers for windowboxes and troughs

Buy the following from nurseries, or grow them from seed. Don’t dig them up from the wild!
For sun:
Red valerian – annual that self-seeds
Thrift (Armeria) – evergreen perennial
Thyme plants or seed – evergreen perennial but can look scruffy in winter if not trimmed.

For sun or shade:
Bluebell (Hyacinthoides (formerly Endymion) non-scripta) – perennial bulb, and self-seeds.
Cowslip (Primula veris) – perennial and self-seeds.
Foxglove (Digitalis purpurea) – self-seeds, flowers in second year (biennial) – wild and garden forms available.
Primrose (Primula vulgaris) – perennial and self-seeds – wild and garden forms available.

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