Now is a great time to divide your summer-blooming perennials (fall blooming perennials should be divided in the spring). Dividing perennials, which is simply cutting the plants into smaller pieces, helps control their spread, reinvigorates them, and provides a great supply of material for transplanting. This task doesn’t need to be performed every year, but chances are your garden will have some candidates for division now. Here’s some more discussion on the benefits of dividing perennials.
If you find that your garden is overcrowded, dividing perennials will reduce the extra material they have grown over the last few years and bring them back into their proper proportions. This is especially useful if you have perennials that are aggressive spreaders such as Japanese anemones, Bee Balm (Monarda didyma), and lamb’s ear (Stachys byzantia).
Most perennials will slow down bloom production and even begin to die back in their centers as they spread and get larger. Dividing these plants reinvigorates them by restarting the plant’s desire to grow and spread. For example, Astilbe will display bigger and more healthy blooms with regular division, and perennials with matted root systems such as Yarrow (Achillea) and lamb’s ear (Stachys byzantia) will experience die back in their centers if those root systems are not thinned by division.
Dividing plants gives you lots of what you like most for transplanting in other areas. If you have an area that you want to fill with more perennials, there’s no need to buy more plants if the ones you love are already growing in your garden. Just transplant your divided pieces into those areas.
You’ll know your plants need dividing when their blooms aren’t as healthy and large as they once were, their centers are dying back, or when their lower foliage is unhealthy. Actually dividing the perennials requires digging the plant out of the ground, separating its root system into three or four divisions, and replanting the pieces you wish to keep. If you’re unsure about your own perennials or want more information on when and how to divide, contact your landscape professional.
Seasonal Color Specialist