I had a pavement garden put in by the city council, beneath our Amsterdam apartment, soon after we moved here 13 years ago. Such pavement gardens are narrow strips, right up against the buildings, were the pavers get lifted and removed, making the sand beneath available as a planting area for residents. You need to draw up a plan and get written permission from your neighbours, when you request a new one – It was quite exciting I can tell you. Well, my neighbours approved my idea and after the council workers set it up for me, I poured in a couple of bags of compost and planted it up with Rosemary (Rosmarinus officinalis), Purple Sage (Salvia officinalis ‘Purpurascens’), Rue (Ruta graveolens)and Lavender (Lavendula augustifolia). Everything in there grew really well, even though the little plot faces full south, is under a bay window and gets little rain. It was a lovely, simple Mediterranean herb garden. The herbs were resplendent and many neighbours would snip off a little Rosemary through the growing season, to add to their cooking. That shrub was enormous and very healthy.
Then last year, things started to go rather pear-shaped in the geveltuin. The mature Rosemary had some damage. More than a little damage, in fact it looked decidedly nibbled all over. Only a few flowers pushed through and the plant looked increasingly bedraggled. We also noticed very pretty, metallic striped beetles on the Rosemary sometimes. Often, when we brushed against the shrub, some of them would shoot off and bounce off the pavings making a characteristic crackling sound. We didn’t realize back then but our Mediterranean herb garden was under attack by the Rosemary Beetle (Chrysolina americana).
This week, enough was enough. The Rosemary looked barely alive and as neighbourhood Rosemary bushes were starting to really bush out with lush deep green new shoots, our looked downright grey. To make matters worse, the Purple Sage was almost gone, the Rue totally desiccated and the Lavender was a shadow of its former self. The beetles were more plentiful than before and my herb garden was no more.
Know your enemy
I read up on the Rosemary beetle and planned my counter attack; Hard pruning, taking a few insurance cuttings, enriching the soil and removing the thick blanket of dead leaves (which I was building up beneath the shrubs, out of laziness really). Finally a good drenching with water.
As you can see in the video, I shook out the shrubs onto a bright blanket, placing tumbling beetles and larvae in a glass jar which became enormously interesting to local kids. We had about 30 bugs in there by the end. The leaf layer was totally cleared and I hard pruned all of the shrubs. The Rue had to go, sadly as I loved it and few people seem to grow it these days. However, I was delighted to find that it had spawned a few babies, growing between paving slabs so I hope they will make it in the newly prepared plot. My daughter and I scoured the geveltuin and surrounding area for more beetles and larvae before giving the remaining plants a really good watering and then enriching the soil slightly with a bucketful of spent compost (which I collect from my old rooftop pots). Later, I added a couple of lupin seedlings which I had on the roof, a few radish and beetroot seeds, some potted tulips from the kitchen balcony and some self-seeded Lemon balm, which was growing across the street in the gutter. A cheap and cheerful geveltuin makeover! The project took a few hours and I am satisfied with the result.
It took me a couple of years to give in to the fact that these pin-stripe armored beetles were beautifully munching through my herb garden and that I was providing them with perfect overwintering conditions. From now on, I intend to keep the plot more open and airy, more species rich and attractive to predatory and pollinating bugs and I will water the plants regularly, especially when they appear to be under pressure. I also plan to place a bird nesting box on the street tree across the pavement and will feed the plants with comfrey & nettle tea, when the mood strikes me.
In the hope that I can help others to spot Rosemary beetle and deal with it more quickly, I made a short video, which you can see here. My daughter and I had fun editing this one so we hope that you find it useful.
Squish or Release?
So what happened to the collected beetles and larvae in the glass jar? Well, I did squish one on the pavement in frustration, the day before the clean up operation and I felt really bad about it. Killing them didn’t feel right at all and I knew well that these bugs were here for a while and I had allowed them to get out of control. I needed to help nature to restore beetle balance. After a chat with a gardening friend, I decided that the best solution was release these little beasts into a more bio-diverse area, away from aromatic herbs and where natural predators could feast on them or they had a chance to escape and live among other species of insects. This morning, we took them to a grassy area, close to water and let them go.
Have you got a beetle problem? If so, how are you dealing with it? What would you have done with the captured beetles? Do you have other herby-pesty problems and can you think of better ways for people to keep their herbs healthy? Do let me know as I would love to hear!