Knowing When to Dig, Divide and Plant Perennials – Forum

Knowing When to Dig, Divide and Plant Perennials – Forum

Did you know that Benjamin Franklin enjoyed gardening? One of his most famous sayings was, “A preserved peony is an acquired peony.”

Speaking of peonies, September is a good time to dig, divide and transplant these perennial beauties. Other perennial flowers are best divided and replanted in the spring rather than the fall. How do we know which perennials to divide for which season?

Before we answer this question, how do we know if perennials need to be divided? “Partitioning” is a horticultural term that refers to dividing a perennial clump into multiple sections, each of which can then be replanted.

Perennials need to be divided if the center of the clump is dead, and all the good parts are on the outer perimeter. Or if your perennials are no longer thriving as they used to, they may be overcrowded and need to be divided.

Even if perennials aren’t in dire need, they can be divided to share some with other gardeners. We may need to move the plant to a different place in our flower garden.

Some perennials can stay in place for many decades without needing to be divided, such as peonies and bleeding heart. Other plants bloom more profusely if divided every three to four years, such as iris, delphiniums and lilies.

Which perennials divide in the spring and which in the fall? There is an easy way to remember. If it blooms in spring, dig in fall. If it blooms in the fall, dig in the spring.

Think of the tulips that bloom so beautifully in the spring. Autumn is a good time to plant or dig up bulbs and reset them. Peonies, which bloom in late spring, are traditionally divided in the fall.

Conversely, perennials that bloom in the fall, such as asters or asters, are dug up in the spring. This spring-dug group includes perennials that flower after midsummer, such as hostas.

Perennials such as hostas, which bloom in late summer, are best divided or transplanted in the spring.
Chris Flynn/Forum

There is a good reason to choose the opposite season for flowering. Perennials are more tender when they are in bloom, because they put in a great deal of effort. Digging a perennial during that period increases the risk of failure.

Perennials that are dug, divided or transplanted now in late summer or fall, usually in September, include peonies, bleeding heart, oriental poppies, lilies, and bulbs such as tulips. Irises can be divided starting in August.

Perennials to dig, divide or transplant in spring include a long list including hostas, monardas, clematis, delphiniums, ferns, ornamental grasses, tall garden phlox, Shasta daisy, Russian sage and many more.

Some perennials are resilient enough to dig in spring or fall. Daylilies are usually divided after midsummer, but can be done at almost any time.


Daylilies are flexible enough to divide at any time, but late summer or later is preferred.
Chris Flynn/Forum

To divide perennials, dig up the parent plant with a fork or shovel. Gently lift the plant from the ground and separate it into smaller sections by hand pulling or cutting with a knife, shears or shovel.

Each section should have three to five strong shoots and a healthy supply of roots. Replant them in the same section they were originally in, then water them well to settle the soil around the roots.

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The Horticultural Research Farm at NDSU will hold two field day events

The North Dakota State University Department of Plant Sciences will host two different field day educational events at the Horticultural Research Farm, located about 40 miles west of Fargo, between Absaraka and Amenia, North Dakota.

First, a Fruit, Hemp, and Vegetable Field Day event will be held on Thursday, September 7, starting at 4:30 p.m., including presentations by several researchers on garlic varieties, apple tree regeneration, cantaloupe and haskapis varieties, and research on flowering hemp. , juneberries, raspberries, and much more. Don Kinzler will give a lecture on the successes and challenges of the 2023 fruit and vegetable growing season.

Dinner will be served at 6 p.m. The event is free, but registration is required by September 6. For more information and to register, visit here.

The Horticultural Research Farm’s second event is called “Branch Out: the NDSU Arboretum Experience” on Saturday, September 9, from 12:30 to 5 p.m. The Dale E. Herman Arboretum includes 35 acres of research farm and contains the largest collection of trees and shrubs in the northern Great Plains with more than 5,000 species, cultivars and selections.

The arboretum is a beautiful and educational place to spend an afternoon walking the grounds where new trees and shrubs are evaluated, selected and introduced if they prove to be adapted to our regional conditions.

In addition to walking tours, NDSU staff will offer programs on emerald ash borer, pollinators, how to improve landscapes, and more.

Registration by September 6 and a $15 fee are required. Registration will close early if the maximum attendance of 75 is reached. For more information and to register, visit here.

    (Tags for translation)Horticultural Research Farm

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