Using Trees to Create a Green Roof or Wall

Rooftops, balconies and green walls all set the same tree problem. Restricted root space, sharp drainage, big exposure and limited soil volume. The trees that thrive here are the ones built for confined conditions.

Five trees that work in containers, on roofs and as part of vertical planting.

What rooftop trees need

A confined and predictable root system. Tolerance of drought, wind and reflected heat. Slow to moderate growth so they do not outgrow the planter. And good looks year round, because there is nowhere to hide on a rooftop.

Little Gem Magnolia

Compact dense evergreen, perfect for large planters. Holds shape, fragrant summer flowers, low fuss.

Bay Tree

The classic rooftop topiary. Slow growth, clips beautifully, gives you culinary leaves.

Orange Jasmine

Container hedge for fragrant balcony screening. Repeat flushes of citrus-scented blossom across the warm months.

Manzanillo Olive

Drought-tolerant Mediterranean tree, ideal for sunny rooftops. Sharp drainage, low water, evergreen silver foliage.

Japanese Maple

For sheltered courtyards and protected rooftop corners. Layered foliage, brilliant autumn colour and a small mature footprint.

Sizing the container

For a mature tree, use a planter of 200L or larger. Smaller containers work for short-term planting but limit long-term root health. Sharp drainage is essential, since waterlogging is the most common cause of rooftop tree failure.

Watering rooftop trees

Drip irrigation pays for itself within a year. Manual watering is workable but easy to skip. Top up mulch every season to slow evaporation.