Q: This hebe bush (pictured) has been growing in my back garden for about 10 years, behind the boiler. It is east facing. It was doing very well until we cut it back a few years ago in April 2021, after which it turned brown and stopped flowering altogether. It looked dead. We had cut it back prior to that, but possibly later in the season. Since then it has grown — in fits & starts. Should we give up and cut it away totally? Or should we just cut it back to its bare minimum and hope for the best? It was taken from a small plant/snip in my mother-in-law’s garden, and as she has since died it is of great sentimental value, plus it is a haven for birds and bees when it is flowering.
CB, Co Limerick
A: Hailing mainly from New Zealand and commonly known as veronica, this large genus of decorative shrubs’ evergreen foliage, long flowering display and generally unfussy nature makes them popular with Irish gardeners. As you so rightly point out, their flowers are also loved by pollinating insects.
But they’re not entirely trouble-free and are vulnerable to a number of diseases including downy mildew, leaf spot and root rot. Your hebe looks like it may be suffering from the latter of these, symptoms of which include severe die-back of entire branches of the plant and slow, patchy, stunted growth that first becomes obvious in spring or after periods of drought. Afflicted plants can soldier on for a couple of years, but never fully recover. Caused by a variety of pathogens in the soil, the textbook advice is to dig up and destroy all parts of the plant.
But hebes are also naturally short-lived plants with an average maximum lifespan of a decade, so another possibility is that your hebe is naturally at the end of its life. Yet another is that it’s a combination of both disease and old age.
While light pruning in late spring or after flowering is recommended to keep small-leaved species of hebes like yours in shape, they typically dislike being pruned hard. However in this case I’d suggest using a clean, sharp secateurs to cut out the dead branches as a last-ditch effort at restoring your plant to its former glory (burn or destroy these pruned branches in case they’re diseased and wash your secateurs afterwards). But leave any healthy branches untouched as the plant will need these to help it regenerate. Then it’s a case of wait and see, with lots of new, healthy growth a good sign that your hebe has a few years of life left in it yet. But if it continues to struggle, then dig it up and destroy all parts of the plant including its root system.
You could also take some semi-ripe cuttings at this time of year (from July-September, using the youngest, freshest growth you can find) to propagate new plants. But again, if the parent plant turns out to be diseased rather than very elderly, then sadly these cuttings will need to be destroyed.
If you do decide to plant another hebe in memory of your late mother-in-law, it’s important to plant it in a different part of your garden to reduce the risk of disease. Also, bear in mind that hebes need a sheltered spot and moist but very well-drained soil in sun or light shade to flourish.
