Most perennials only remain vital and blooming if they are divided regularly. But what should you take into account? And how exactly do you go about it? This article clarifies these and other important questions on the topic.
When and how should you divide perennials?
Perennials should be divided regularly to maintain their vitality and flowering potential. Divide summer- and fall-blooming perennials in spring and spring/early summer bloomers after flowering. The division method depends on the perennial; root balls are usually divided carefully.
Good reasons for dividing perennials
Many perennials naturally lose their ability to bloom over the years. In addition, the middle of the plants may gradually become bare. Then it's time to divide the affected perennials to rejuvenate them.
As a result of this measure, the plants will bloom again and remain vigorous.
Great side effect: Sharing gives you numerous new perennials that you can plant yourself or give as gifts depending on your needs and wishes.
The right time to divide perennials
As a rule, the spring months are the ideal time to divide perennials. However, there are exceptions.
Rules of thumb:
- Divide summer- and fall-blooming perennials in early spring.
- Divide spring and early summer bloomers (bloomed before St. John's Day) immediately after flowering.
After how many years divide perennials?
Remember that you don't have to rejuvenate your perennials every year. Ultimately, the growth behavior and lifespan determine when (for the first time) and how often the respective plant needs division. Here are concrete examples as a guide:
- Short-lived perennials age quickly. Therefore, you should divide them approximately every two to three years. This group includes feather carnations and horned violets.
- Species such as purple bells, early summer asters or burning love need to be divided every four years.
- Long-lasting perennials only reveal their full splendor over time. Let them grow in peace - they might resent frequent sharing. Members of the group include peony, bearded iris, delphinium and bleeding heart.
Dividing perennials – this is how it works
- Place the digging fork or spade into the ground around the rootstock.
- Move the device back and forth several times. This is how you loosen the root ball. Work carefully so as not to injure the bunion if possible.
- Shake off the rhizome briefly or spray it with a jet of water. This makes it easier to divide the respective perennial.
- Divide the plant into two or more sections that are about the size of a fist and have a few leaves or shoot buds. You can pull some perennials apart with your bare hands; for others you will need a sharp knife or even a spade with a sharp blade (for perennials with compact roots).
Note: Small sections generally sprout more vigorously and grow into robust plants more quickly.
What you need to consider about sharing
- Remove diseased and dried root parts.
- Take away the woody center, chop it up and dispose of it in the compost.
- Re-cut any unclean parts with a sharp knife.
- Plant(s) in a new location immediately after division.
These perennials cannot be divided
There are also perennials that are difficult or impossible to divide:
- Species that do not have rooted individual shoots (e.g. magnificent spar and rough-leaf aster)
- Species that form a deep taproot (such as pasqueflower and giant gypsophila)
