Nikki Krieg
In Southern Louisiana, the sun shines most days, we rarely lack for rain, and the earth rarely freezes. This creates an almost year-round growing season. When I am in shorts and eating at the harvest table bounties of squash, peppers and okra, my gardener friend from upstate New York is usually awaiting the end of the last frost and starting to plan out their summer garden. Their “summer” is our spring, summer, and fall all in a few short months. All that to say: we can grow for a long time.
Here in the humid deep South, though, there are certain caveats. One that I find of constant interest and study is the art of perennial pruning. Come early July, I have already spent a lot of time pruning, deadheading, and cutting back my perennials and annuals—native, exotic, all of the above.
The action of pruning herbaceous plants finds its roots in ancient natural history. Plants have been “pruned” by various ways of disturbances, since their creation. Examples of these natural disturbances/prunings include: grazing animals and natural patterns of weather such as fire, flooding, and wind. Humans, for their part, have pruned, for various reasons, since we began cultivating plants and gardens.
There are four reasons I like to prune my perennials (and annuals) often:
More blooms!
When most herbaceous plants go to seed, they start to end their perennial or annual life cycle. Plants, like most species of the earth, have the same evolutionary goal, and that is to carry life onward. Though there are exceptions, generally when a plant has put its seed out, it has completed its yearly responsibility for its species and can, for now, end its reproductive cycle. Therefore, when you prune or deadhead your herbaceous flower heads before they go to seed, you are sending a message to the plant that its work is not done. You are, in essence, telling it to keep making blooms.
Structure
The main reason I prune perennials is for structure and strength. To encourage new robust growth and help plants avoid splitting or rotting, pruning certain perennials by half or two-thirds a couple times a year can do a world of good.
There are a few of my native perennials I purposely prune hard at least once late spring, many months before they bloom. These include: swamp sunflowers (Helianthus angustifolius), Willowleaf Aster (Symphyotrichum praealtum), ironweed (Vernonia gigantea), and all of our goldenrods. These plants are what I like to call “ditch plants” for the fact that they grow in low spots along our roadsides. These ditch plants, among many many others, grow wild and tall. In a giant mass, or at the back of a garden, they may stand up fine but most often than not, in the residential garden, they grow too tall and topple over. We like to cut them back early enough before blooming so they are stronger, a bit more compact, yet still bloom in the fall. You can also prune to encourage a certain type of structure and shape. I, for example, often like to prune a bit of the plant's structure to encourage a cascading effect.
Illusion of Beauty/Health
When you deadhead or prune browning flowers, it just gives an overall beautifying effect to the garden. It is wild how different a garden can appear after a good removal of spent blooms. It does not mean the plant is any happier, it just gives an appearance of perfection and an illusion of more vibrant color. I used to deadhead a lot for this reason alone, especially with my seasonal annuals. Alas, I no longer have as much time for that, but when I can do it, it’s well worth the meditative task.
Plant Competition
All plants have different growth rates and natural forms. Some perennials will quickly overcrowd others due to a faster growth rate or more wild form. You can solve this problem by (1) choosing carefully what plants you plant alongside each other and (2) pruning when needed if one perennial or annual crowds over another.
There are some gardens you don’t want to prune at all, of course. In some gardens, you might leave the brittling grass blades and bronzing seed heads through winter as resources for our wildlife to munch on and find refuge within.
As someone drawn simultaneously to more naturalistic styles of gardening and heavily blooming cottage gardens, I have some more naturalistic areas of my garden for my seasonal musings, and other areas that are more controlled. My overall approach is to aggressively prune/deadhead through the summer and then stop come mid-September. As I watch winter slowly seep in and with it the various shades of browns and fluctuating textures, I let go of control.
Pruning itself is an interesting study in control and our obsessive human need to cultivate spaces. But I also find, at the end of the day, it's an art. No one is out there enforcing rules of how to interact with the plants of your garden, not even when it comes to how to chop away at it. You learn, through trial and observation, what works for your space and through what lens you most enjoy viewing it. There’s no real wrong way—it all depends on your goals/objectives. As always, experiment away.
