One of my interests is alpine gardening on small area. My dearest alpine garden is on the roof of my garage, with sedum, sempervivum, saxifraga, campanula cochleriifolia, etc. This has survived more than 15 years now, through some cold Dutch winters and hot dry summer periods, almost without any additional watering (the roof is in the North, mostly semi-shaded). Not much maintenance is required, but for one continuous plague: grass. If not pulled out regularly, grass will quickly overgrow the alpine plants. This is a bit unexpected because I never put on any fertiliser and the soil must have become rather poor in nitrogen in all these years. Any suggestions to mitigate this problem? Another problem was a leaking roof during heavy rain but that has been solved nicely.
I would like to contact others having the same type of roof garden, to exchange experience, also about the type of plants that do well under these conditions.
How lovely. I don't have any experience with this sort of garden, except for the roof of one Swedish restaurant in Wisconsin. It was all lawn and they regularly put goats up there. A great tourist draw.
Yours is much more beautiful. Please show more pics if you have them! How many different plants do you have? Did this require reinforcing the house?
This type of roof garden was recently featured on one of our gardening TV programmes - a great way to garden if you have limited space. Grass is a problem in all of our gardens! Well done - it looks great.
I do not know if you are still watching this thread or not. I do not have green roof, but wish I did. Anyway, where did the grass come from? Does it spread by runners or seed? If it is spread by seed, you could try some corn gluten meal as a pre-emergent. http://www.dirtdoctor.com/view_question.php?id=17
I do not know how everything else would respond. It stops seed germination, but not reproduction by other means, and it depends on the time of year you apply.