A Lawn of Grape Hyacinths

I planted a few bulbs of grape hyacinth (muscari) in my front garden some years ago. Now I have a virtual lawn of them every spring, and I see they are beginning to creep into my neighbours garden as well.  They make a good display though, and as nothing much else interesting grows there this time of year I'm happy to let them get on with it and just keep the area tidy.