We put sedum cuttings down on a roof 3 years ago, didn’t realise we had to feed the sedum, waiting for the show of colour last year combined with a very dull summer, there is a lot of moss in place. We applied seaweed on it last autumn which I will do shortly again. Just wondering what type of fertiliser, could I use that won’t harm the sedum but will reduce the moss, there is also a part were clover is growing. roof is north facing. found on nz website the ratio n12.6/ iron 8 and sulphur 1, can’t find if sedum will thrive on this.
Remove the clover as it will take over.
North-facing is not ideal and tends to encourage moss as roof gardens do best in full light.
Small ferns might be a better bet, such as hart’s tongue fern or polypody fern, and the moss wouldnt matter then.