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Marin IJ Articles

Breaking up is NOT hard to do

  • February 1, 2020
  • Karen Gideon
  • Few activities offer a greater example of “give and take” than gardening with perennials. We care for our plants by watering, mulching and composting over their lifetimes while they offer us beauty, fruit, and flowers.  With time your favorites age as they develop woody crowns, crowded and clumped roots, and produce less bounty.  Ah, the specter of fading beauty presents itself once again and we are called to action.  Fear not, brave gardener – there is an easy remedy.  It’s time to “divide and conquer!”

    Plant division is an ancient practice that increases the vigor of a plant and provides new plants for additional landscaping or gifts for like-minded gardeners.  While we’ve all heard that “breaking up is hard to do,” actually it’s not. Division is a great way to get new plants and infuse your garden with new life.  It’s also a prudent thing to do to perennials every few years and is usually successful if you follow some basic principles.

    Most division takes place when the perennials are finished blooming in the fall and in the spring when conditions are favorable. Since plant division involves splitting or dividing of the crown and root ball, its use should be limited to plants that spread from a central crown and have a clumping growth habit like daisies, asters, agapanthus, yarrow, anenomes, achillea, irises, columbine and chrysanthemums. Fruits and vegetables can also be divided – like rhubarb, artichokes, asparagus and herbs including thyme, marjoram and tarragon.

    Division is a soil-building opportunity!  While lifting, forking and dividing your plants, it’s a chance to amend old and prepare new soil. Work in some compost, leaf mold and bone meal when you build the new home for divided plants.

    While the technique may differ depending on the type of root structure of the plants to be divided, there are common tools to get ready. Have a bucket of water nearby, a fork or shovel or two for lifting, and implements for either cutting the roots or pulling tubers apart and some isopropyl alcohol or nine parts water and one part bleach to sterilize your knives and pruners. 

    Trim and water the plants to be divided a couple of days before you divide.  Do your division on a cool, cloudy day or find a shady spot.  Have the soil in the new beds prepared and fill your gift pots with moist soil and compost.

    The plants need to be carefully lifted from the soil.  Depending on size and consistency of the soil, you can lift them with a shovel, hand-forks, pitch-forks, or hand trowel.  Dig around the base of the plant deeper than the root structures. If attempts to lift the plant out of ground prove too difficult, sending a shovel or spade into the center of the crown will split the plant.  Working as a team or one side at a time, the plant can be pried apart into two or more clumps.  Smaller plants can be divided by one person by using forks back to back in the center.

    Lift and shake off any loose soil. Rinsing the roots with water can be helpful.  Look for natural fractures between bulbs, root clumps, or rhizomes and gently split these fissures with your hands.  If they don’t come apart easily, they can be cut with a sharp, clean knife. 

    All plant divisions must be kept moist during this process.  If the roots or rhizomes are allowed to dry, the plants may not survive.  If there is a delay in replanting the new plants, keep them in moist soil mix in a container or in water.  Be careful not to damage the roots and keep the portions good sized.

    Successful division produces new roots.  To keep the plant’s energy in the recovering root structure, trim off any dead growth and some of the leaves at the top of the plant but retain enough greenery so the plant is can still supply energy to the roots. The remaining mother plant from which you took the divisions can be replanted immediately. Water thoroughly, add compost and mulch the replant. Keep an eye on your new plants and protect them from extreme weather.

    Over the next spring and summer, your newly divided plants will begin their new lifecycle.  Blooming, growing, thriving, the plants proliferate. You’ll fall in love again. And in due time, when the fade of age begins, you’ll be ready again to divide and refresh.