Do they need maintenance?

All roofs require maintenance and green roofs are no different. Depending on the species of plants, a certain amount of ‘gardening’ is needed; with a sedum roof this can amount to very little, but with wild meadow flower roofs, or ‘intensive’ roofs with shrubs or trees, the pruning and weeding commitment is greater. Green roof warranties can have a component of maintenance inscribed to lessen the risk of failure, but not always - make sure you check that it is included if you want it.