Will perennials growth through black lava rock?
I bought a new house last fall and would like to redo the landscaping myself. It currently has some perennials planted in that area. My plan is to put lava rock down instead of the current mulch. Will the flowers sprout through the lava rock or will I have to dig up all the bulbs and replant somewhere else? The flowers in area are lilies.
Allen County Indiana
Lilies can grow through black lava rock mulch provided it is not overly deep, However, I do not recommend using inorganic mulches of any kind for several reasons. They interfere with routine maintenance such as adding compost, splitting perennials and removing the weeds that invariably sprout through the mulch. Further, most inorganic mulches eventually settle, mixing with the soil and requiring replenishment.
A better approach would be to use an organic mulch which will eventually decompose, feeding your soil. Compost can be added and the mulch can be topped up at any time.
Another alternative is to plant a living mulch, or plants that fill the open spaces and serve to shade the soil. There are many to choose from. My personal preference is for perennial geraniums (ie true geraniums), lamium and in some locations even ajuga (Bugleweed).
Here is a link to some additional information on mulches: