Dividing and Transplanting Perennials

Perennials, such as day lilies and hostas, can provide color and vibrant foliage year after year. Yet at some point, these plants may need to be divided and transplanted if they are to bloom and continue to thrive. There are certain signs to look for that indicate when they should be divided as well as certain steps that should be taken to successfully divide and replant them.

Characteristics of Perennials

According to the Resource Guide for Iowa Master Gardeners (Iowa State University Extension), a perennial is a category of herbaceous plant that can survive for three or more years. An herbaceous plant dies down each winter and survives the cold by relying on its root system for renewal in the spring. The word ‚”herbaceous” refers to the type of shoots produced by the plant, which is soft, green and non-woody. In addition to perennials there are annuals, biennials, and tender perennials, categories that are based on their life cycle.

Rejuvenating Old Plants

Many perennials may flourish in the same spot for years because they are slow growing. Plants that need to be divided may have dead spots in the center, have quit flowering or be producing smaller blossoms. Other signs, according to the University of Illinois Extension are a plant that flops and requires support, is less vigorous or has grown beyond its bed or container. When this happens, the perennial may need to be divided.

It is important to note that a perennial can be divided just to create new plants for other parts of the garden or to share with friends.

Techniques for Dividing Plants

The gardener should do the following:

• Dig up the plant making sure that there is a significant amount of healthy root included
• Remove the unhealthy or dead parts of the plant
• Clean off the soil from the root system – this will help show where the plant can easily be divided
• Pull the roots apart by hand or by using a sharp knife- make sure that there is a significant amount of crown and root in the divided plant
• Dig a hole large enough to accommodate the root system and some degree of growth for the root system
• Plant the new plant at the same depth as the original plant
• Water after transplanting and repeatedly to ensure that the new plant successfully takes hold

When in the year to divide the plant depends on the type of plant. According to the Resource Guide, spring blooming plants should be divided in the fall, early enough to allow them to take root before the winter. Summer blooming plants such as coneflower and fall blooming plants (mums) can be divided in the spring.

Perennials can provide an ongoing source of new plants. Careful division and re-planting will facilitate the continued flourishing of these plants.