Do my plants need a Chelsea Chop? Here are 3 things to know about the pruning method

Back a few decades ago, when I used to spend time chasing a little white ball around a golf course, I received one very valuable bit of advice from a learned golf pro.

“If you go for a lesson with a pro” he said, “and you get a list of 15 things to improve about your swing, you haven’t had a lesson at all.”

His point was simple — for the weekend golfer, it is most effective to pick one thing at a time rather than try to improve on a dozen things at once.

Gardening is no different.

For some people, gardening has a simple albeit rather low bar. One, buy a plant. Two, plant a plant. Three, occasionally drop a little water on said plant, and four, check to see if the plant is alive a year later.

Now there’s nothing wrong with this model. Some of us may like to spend all our waking hours tending to the unreasonable needs and wants of some rare Himalayan daphne planted in an inappropriate climate. But it is reasonable for someone who plants a plant to want to occasionally go to a movie, join a few friends for happy hour, or go for a picnic on a nice summer day.

I don’t know any of those people — but I’m sure they exist.

But this piece is directed at the folks who have mastered the basics and are ready to level up — not a total dedication to single-minded, no life outside of plants kind of existence. The Chelsea Chop is one of those easily manageable garden techniques that can help you take your gardening to the next level.

What is the Chelsea Chop?

The Chelsea Chop is the practice of cutting back (by one-third to one-half) the new growth of some herbaceous perennials and annuals to keep them from getting too tall or leggy, or to change the flowering and growth characteristics of target plants. The name comes from our friends in the British gardening world who coined the term because the most common time for the procedure is late spring, right around the time of the Royal Horticultural Society’s famed Chelsea Garden Show. Here in Kentucky, we might call it the Post-Derby Chop.

How does the Chelsea Chop work?

Whatever you call it, the late spring/early summer cutback puts some basic plant physiology to work for the gardener. In most plants, as new shoots grow and produce new leaves and buds, the cells in the growing tip produce a class of plant hormones (auxins) that diffuse back down the stem where they inhibit lower buds from opening up and producing additional shoots. We refer to that as apical dominance. But when you cut back a stem and remove that group of auxin-producing cells at the shoot tip, the level of auxin diffusing down through the stem decreases, allowing those lower buds to open up and form new shoots.

The result of a well-crafted Chelsea Chop is two-fold. First, you end up with a shorter, more densely branched plant as formerly suppressed buds are released to produce many more shoots. Plants get bushier but don’t grow as tall. Chopped plants tend to make more but smaller flowers. Second, the Chelsea Chop tends to delay flowering as the chopped plant reorganizes its resources and gets back to business.

For a variation on the theme, you can Chelsea Chop a few specimens and leave others uncut to spread out the bloom time (Chopped plants delayed flowering and unchopped plants flowering earlier) or cut the front of a mass and allow the back stems to remain uncut. Some perennials such as cat mint (Nepeta species and varieties) can be chopped after bloom to encourage a second flush of flowers.

What plants can be Chelsea Chopped?

In general (and do keep in mind that this does take a bit of experimentation as the only absolute rule in gardening is that there are no absolute rules!) the best candidates for the Chelsea Chop are those that flower later in the summer or fall. Many spring bloomers, especially very early bloomers, tend to have their flower buds performed below ground during the previous fall. Plants such as daffodils, peonies, and iris don’t make good candidates.

Many later blooming species don’t have preformed flower buds that overwinter underground. Most of these plants produce new shoots and leaves from their growing tips and then at some point in the season (usually in response to changing day length), a switch flips in the shoot tips and they change from producing leaves to making flowers. These are the best candidates for the Chelsea Chop. Some excellent examples include fall-blooming asters, chrysanthemums, and butterfly bushes.

Another group of plants that make good candidates are shrub and herbaceous perennial plants grown primarily for their foliage. Purple smoke bush (Cotinus coggygria varieties) and common ninebark (Physocarpos opulifolius selections) have perfectly nice flowers, but their main garden event is the brightly colored foliage. Giving them a good Chelsea Chop this time of year may result in few (or no) flowers, but it will keep the plant producing bright, fresh-looking foliage on a more compact plant.

Another way I use the Chelsea Chop in my garden is to manage some of my annuals. Whether it is the bright foliage of coleus or the billions of blooms on lantana, an occasional cutback can keep them from getting too tall and flopping over after a midsummer thunderstorm. It has the added advantage of reducing the amount of water-loving foliage so can reduce the need for watering.

Whatever your motivation, the Chelsea Chop is a great next-level tool to help you get more out of your garden. Give it a try!