Have you ever wondered how to have a vibrant roof with reasonable coverage and prolific flowering, without needing too much maintenance? For many this may be the ideal of how a green roof should be.
There will always be a trade-off, just as any ground level garden needs maintenance to keep looking good, but on a rooftop maintenance can be much trickier. The higher levels of nutrition that increase the possible range of roof plants and provides stronger, faster growth will also encourage more weeds.
Lowering the nutrition enough can vastly reduce weed establishment, and therefore maintenance requirement, but then your intended plants will be smaller, slower and produce fewer flowers. This is great for really hard to access roofs or those which aren’t overlooked.
A good compromise for a great looking green roof with reduced maintenance is to use a richer green roof substrate, but plant plugs more densely and mix in ground cover plants among other more upright varieties, or even spread seed or cuttings between them. This will result in a bright and vibrant plant community that will evolve over time with fewer alien species to complicate the maintenance programme.
Of course, high nutrition is relative to green roof substrates and is still ultra-low compared to most composts – more information to be published on our website in the next month. And it goes without saying that nutrition is managed within the manufactured substrate, never added as fertiliser.