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When to Cut Back Perennials

Jennifer NicholsField Notes

As the days become longer and the soil begins to warm, perennials that have been dormant all winter begin to push towards the sun. Through the next few weeks, if the snow ever subsides, we will begin to see this transformation.

At GreenWeaver, we like to leave most perennials standing during the winter, their dried stems adding winter interest in the garden, and providing food and cover for birds and insects.  But when some green starts to show at the base of these plants, it is time to remove the dried foliage to make room for new growth.  There are a variety of ways to do this.

Some plants like Threadleaf Coreopsis (Coreopsis verticillata), have very fine stems which can easily be broken off at the base.  No tools are needed except maybe a pair of garden gloves.

Other plants like Blue Flag Iris (Iris versicolor), melt into a pile of leaves over the winter, and can simply be picked up in the spring.  A few stems may remain attached at the base, and they may need to be pulled or cut.

Perennials such as Black-eyed-Susans (Rudbeckia fulgida), or Purple Coneflower (Echinacea purpurea), with thicker stems can be removed by a combination of methods.  I tend to break them off, grabbing several stalks at a time in one hand, while using my handy Felco pruners to cut away stubborn stems with the other.

Time to cut back Northern Sea Oats

It is definitely worth leaving Northern Sea Oats stand through the winter, but with spring around the corner, it’s time to cut this plant back.

Ornamental grasses can be the most labor intensive perennials to cut back.  For very large clumps, we tie the stalks together as tightly as we can, or have one person hold the clump, and then cut back to about 6 inches with either hedge shears or hand pruners.  As a side note, one of the most popular ornamental grasses, Maiden Grass (Miscanthus sinensis) is appearing on many invasive plant lists.  Northern Sea Oats (Chasmanthuium latifolium), Little Bluestem (Schizachyrium scoparium) , Broom Sedge (Andropogon virginicus), and Pink Muhly Grass (Muhlenbergia capillaries), are all terrific substitutes, and are native to our region.

As you are cutting back your perennials, if you notice that any of them are dying out in the middle, this is a sign that it is time to divide them.  If you have a spot for them on your own property, simply use a shovel to dig out about one half of the plant, and move it to the new location.  Another option, and one of the great joys of perennial gardening, is to give the plants to friends.  Check around the base of the plant before you give it away to make sure you are not giving away any weeds also.

After cutting back your perennials, clean-up can easy if you had the foresight to toss the dried perennials on a tarp or in a wheelbarrow as you go.  Or, if you are messy like me, you can always pick up your piles with a rake.  We compost this debris either on site, or take it to a local composting facility.

I always find the week or two immediately following a spring clean-up to be a bit barren in the garden.  But if you watch carefully, it can also be a very exciting time, as different perennials push through the warming earth in their own individual ways, with the promise of wonderful things to come.