Pruning Lavender & Woody Perennials

Hello, fellow lovers of all things green,

At last, the big garden cleanup. I spent hours cleaning up branches and sticks and cutting down the ornamental grasses left dry over winter a few inches above the ground. Hedge trimmers or chainsaws (for those braver than me) are perfect for cutting the tall grass. Then, I removed the dry plant debris left from last season to provide a habitat for insects and food for wildlife. The woody perennials or semi-shrubs such as Butterfly Bush, Asters, and Lavender are the most confusing to folks on how to prune. So here’s the skinny:

Ann DeCamp 
http://www.anndecamp.com/

How to Rejuvenate Woody Perennials

It is best to rejuvenate Butterfly Bush (Buddleia davidii) each year by cutting them to six to eight inches above ground level. Better yet, replace them with a native plant alternative far more beneficial to pollinators, including butterflies. For example, there’s Summersweet (Clethra alnifolia), New Jersey Tea (Ceanothus americanus), and Buttonbush (Cephalanthus occidentalis) for the shadier spots.

Then there’s the late-season glory of New England Aster (Symphyotrichum novae-angliae), whose deadwood should be removed in early spring. For hydrangeas and clematis, wait until new growth emerges before pruning back the deadwood. Be patient; this year may be an anomaly of new life starting later due to the single digits endured over winter.

Ann DeCamp’s lovely garden. Garden Design by Mary Stone and Marty Carson

It’s fun to revisit projects from long ago designed with my colleague Marty Carson, such as Ann’s in Scotch Plains, New Jersey, whose lovely garden we installed several years ago. Ann is an avid gardener and an extraordinary photographer who kindly shared her photos.

She loves Lavender, harvesting the bounty of blooms as potpourri.  Pruning lavender can be tricky and take some finesse, just as growing it does, unless you have well-drained soil, full sun, and good airflow around the plants. Prune them each year to improve their vigor and extend their life.

Garden Design by Mary Stone and Marty Carson

How to Prune English Lavender

You can prune Lavender after the bloom or up to mid-spring without foregoing this year’s blooms. While at it, you can use the cuttings to propagate new plants. Dip the ends into rooting hormone and start them in a moist, sandy potting mix.

English Lavender (Lavandula angustifolia) is the most common and toughest Lavender. It is often used to form a low hedge around an herb garden. To keep it compact, cut English Lavender by two-thirds or three nodes above the bare wood in mid-August, allowing new shoots to harden off before winter. Then, tidy them up with light pruning in April.

When tending to plants that have not been heavily pruned each year and have become overly woody, you’ll need to phase in pruning to rejuvenate the plant. Trim each branch by a third or a half, never down to the brown wood, ensuring viable leaves remain on the plant. Thin out the oldest stems to encourage new growth. Then, prune lightly again in the fall to shape the plant.

How to Prune Phenomenal Lavender

‘Phenomenal’ Lavender (Lavandula x intermedia)

There’s a separate way to prune the later-blooming Phenomenal Lavender. Lavandula x intermedia is a comparatively new introduction exceptionally tolerant of heat, humidity, and harsh winters. These lavenders have longer flowering stems, which are lovely and flow with the wind, but they are less tough and cannot be pruned to the leafless, bare wood. They are best cut in late August to the mound of foliage below their spent flowering stems.

Whichever Lavender you have, remember it won’t rejuvenate on old wood. So, if that’s what you’re left with, it’s time to replace your deadwood with something new. The same is true in our garden of life.

Garden dilemmas? AskMaryStone@gmail.com and your favorite Podcast App.

Other helpful tips in Reasons to Prune 

There’s more to the story in the Garden Dilemmas Podcast: