Updated: Nov 7, 2021
My plant of the month for August is Verbena bonariensis - if happy it seeds like crazy, it flowers all summer long; its height means that it adds stature to a border without either drowning out the plants beneath it or hiding a good view, but here is another reason to grow this popular plant - it seems that Swallowtail butterflies love it.
We have a lot of V. bonariensis in the garden; so much so that it risks becoming a pest and one statuesque plant self seeded itself into the path adjacent to where we eat our lunch. In a nearby flowerbed is fennel - both common and bronze - which I have grown from seed over the last few years. Swallowtails love fennel, but we have a pair who have decided they prefer V. bonariensis and we have spent quite a few happy lunch times watching them fly around and settle on the Verbena flowers where they feed contentedly.
We think we have also spotted their caterpillars. Normally these prefer fennel, I am told, but I found them on the aptly named Buddleija - more commonly known as the "butterfly bush". Here is a photo of one on some fennel.
To get back to V bonariensis; it is a very versatile plant which, over the last 15 years has swept to popularity because it is easy to grow, loves sunny and dry conditions, looks great in gravel or Mediterranean gardens. It also tolerates a wide range of soil types. It is a perennial and dies back to a floret of leaves close to the ground each winter. The flower heads persist and we leave many of them over winter, as dried flowerheads, because birds like the seeds and because they look attractive. This also, of course, gives us plenty of "nursery stock" for the following year as uneaten seeds fall to the ground and germinate. In fact, if you are not careful, it can become a complete menace!
Here are two photos of it in our dry garden - which I am hoping to enlarge into a full-on gravel garden over the next year.
The first photo is a close up of the top of the flowers. The very tall grass is Stipa gigantea - which I will describe more fully in a future blog. The rose is Sally Holmes.
This second photo gives you an idea of how it blends into an airy prairie style border. Here it associates with Euphorbia charachias, Yucca gloriosa, some gaura to the left and another rose - Rosa moyesii Hupehensis, which has marvellous flask shaped hips in the autumn. To the right are "lamb's lugs" - or Stachys byzantina, another plant which absolutely loves it in the difficult conditions of our dry bed.