Most snow-on-the-mountain seeds grow the following year after they are produced. However, a smaller percentage of seeds will remain viable for two or three years. Cutting or shredding plants can be very effective in reducing seed production and the number of plants the following year. Keep in mind that all snow-on-the-mountain plants don't flower at the same time. Some may start to flower in June, and others may flower in September, so it may be necessary to take that into account to find the best cutting time.
