By Kat Harrold
Photos by ~ Kat Harrold
Sedums may be great for the hot dry climate of the green roof there are more colorful accent plants to consider such as bulbs.
Early spring when sedum album is just starting to wake from its winter’s nap Snow drops (Galanthus nivalis) spring forth with their deep green foliage and delicate white flowers.
Other excellent spring bulb choices are dwarf iris, crocus, daffodils, tulips, and chionodaxa. As the seasons progress, splashes of color can be added to the roof with bulbs such as allium and cyclamen in summer and early autumn.
Many of these bulbs are native to the harsh environments of the middle east and western Asia making them perfect candidates for the green roof environment.
The general rule of thumb when planting bulbs on a green roof is to cover the bulb with 3 times with the amount of growing media as its height with the crown facing upwards. In other words if you have a 1 inch tall bulb you want to cover it with 3 inches of growing media. Therefore, larger bulbs will have greater success in deeper green roofs with a 4 inch or greater growing media depth.