Flowering perennials are a staple for the garden. Each year they reward with brightly colored blooms, interesting foliage and pleasing form.
Perennials can be lower maintenance than annuals, but periodical chores need to be done. Dividing and renewing the planting for best growth is one of those chores.
There is no set rule for how often they need to be divided, as it depends on the plant’s habits. Aggressive growing plants need dividing more frequently, while the slower growing peony may never need dividing. Many perennials would probably be best divided every three to five years.
Knowing exactly when to divide depends on the answers to three simple questions. If the answer is yes to any of the following, then it is probably time to divide most common perennials.
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▪ Has flowering decreased? Overcrowded plants will not flower as nicely. This is true of daylilies. So if you think the plant should have more flower stalks, then it is time to divide. Overgrown clumps compete with themselves, which leads to a reduction in flowers.
▪ Does the plant have a doughnut hole? As crowns mature, oftentimes the center dies out. New growth comes from around the outer edges of the crown. Ornamental grasses and some hostas suffer from this problem. Dividing is one way to prevent this problem.
▪ Has the plant outgrown its allotted space? Some plants spread rapidly, overtaking their neighbors’ place. Failure to divide rapidly growing plants lets them aggressively choke out of their neighbors and overtake the garden. Monarda and Nepeta do this, as do many others. Simply remove the shoots or dig and replant.
A nice-sized division should contain no more than three to five shoots or growing points. Planting too large of a division will result in a more rapid turnaround and the need to divide again. A clump that is too small will take longer to re-establish and will more than likely result in diminished flowering.
Dividing a perennial can be work, but it is one of the great joys of gardening to see a plant renewed and ready to create a show in the garden. When tackling this project it is often best to lift the clump and then gently pry or cut the plant into the nice-size divisions.
One last comment: Don’t feel like you need to plant every single start back into the garden or parade up and down the street trying to give them away. It is OK and life will continue if you throw away the extras. There are so many plants to grow and so little time and space.