An attic garden is a strange, generous little space. You get light, privacy and a view most gardeners would envy, but you also get sloping ceilings, awkward corners, a dormer ledge that seems purpose-built for a trough, and a staircase that has to be negotiated with every bag of compost. Choosing the right containers is therefore less about style and more about solving a set of practical problems: weight, depth, drainage and wind.

Start with the floor, not the plant

Before you fall in love with a handsome glazed pot, do a little arithmetic. Damp compost weighs roughly a kilogram per litre, and the container itself adds more. A 30cm pot holding 20 litres of wet compost can easily reach 25kg once a tomato plant and its supporting cane are included, and a 40-litre shrub pot can tip the scales at 45kg or more.

• Spread the load: several medium pots are kinder to a floor than one enormous one, because the weight is distributed across more joists.
• Keep the heaviest pots near load-bearing walls rather than out in the middle of the room, where floors flex most.
• Think about the route in. Bags of compost and large pots have to come up the stairs, so buy in stages and decant compost into smaller buckets at the bottom.
• Weigh up a window ledge or dormer sill carefully. These are often decorative rather than structural, so stick to lightweight troughs and small pots there.

Containers that suit awkward corners

Attic rooms are full of unusable geometry, and the right container can turn a dead corner into a productive one. Long, narrow troughs of 60–80cm fit neatly along a dormer sill or beneath a low sloping wall, especially if you keep them to 20–25cm deep. Square pots pack together far more efficiently than round ones, so a row of square 5-litre pots will give you noticeably more growing space than the same number of circular ones.

For head-height problems, a low, wide bowl works better than a tall pot, and a small tiered staging unit lets you use vertical space without building up towards the ceiling. Wall-mounted troughs and railing planters are excellent for herbs and strawberries, but they must be fixed into something solid, not just plasterboard, and never hung over a sloped roof surface where they could slide or drip.

Match depth and volume to what you grow

Depth matters more than diameter for most crops, so choose containers by the root space required. As a rough guide:

• 15cm of compost: salad leaves, radishes, chives, basil, coriander and other quick herbs.
• 20–25cm: strawberries, bush beans, chillies, peppers, thyme and rosemary, which prefer a slightly cramped, well-drained pot.
• 30cm or more: tomatoes, cucumbers, carrots such as 'Amsterdam Forcing', beetroot and dwarf French beans.
• 40cm and 40 litres upwards: potatoes, parsnips, maincrop carrots and rhubarb.
• 45cm+ for shrubs: skimmia, choisya, hydrangea, camellia, bay and Japanese maples all need a generous, deep container to look well for years.

Materials: what is worth carrying up the stairs

• Terracotta and glazed ceramic: heavy, stable in wind and beautiful, but they dry out quickly and can crack in a hard frost.
• Plastic and recycled plastic: light, inexpensive and easy to move, though thin walls can become brittle after a few summers.
• Fabric grow bags and fabric pots: very light, superb drainage and air-pruned roots, but they dry out fast and need watering almost daily in summer.
• Galvanised metal troughs: slim and smart along a windowsill, though the compost heats up quickly in full sun.
• Wooden planters: good insulation for roots, but heavy once soaked and best lined to slow rotting.
• Self-watering containers: brilliant for tomatoes, salads and busy weeks away, less suitable for Mediterranean herbs or shrubs that resent wet feet.

Drainage, wind and what is underneath you

Every container needs proper drainage holes, and every container indoors or on a ledge needs something beneath it. Deep saucers, trays, capillary matting or pot feet will catch the overflow that would otherwise stain a ceiling or upset a neighbour below. Empty the saucers after heavy watering rather than letting pots stand in water.

Wind is stronger at height, so choose low, wide pots over tall narrow ones, group containers together to shelter each other, and avoid anything that overhangs a roof edge or gutter. If a pot sits on a flat outdoor ledge, weight the base with a piece of paving slab or a couple of bricks.

Compost, feeding and keeping things going

Use a peat-free multi-purpose compost for annuals and a soil-based mix for long-term shrubs, which benefits from the extra weight and structure. Attic gardens dry out faster than ground-level ones because of wind, reflected heat and shelter from rain under the eaves, so water thoroughly rather than little and often, and check pots daily through the summer. A slow-release feed at planting, topped up with a liquid tomato feed from midsummer, will keep most containers productive right through to autumn.