July can be a funny month in the garden – too much heat and everything has gone mad, too much cool damp weather and there seems to be a lot of green around and not enough colour to balance it out. And, yes, of course green is a colour too, as writers are always keen to remind us. But I have had clients ring me up and say that there is no colour in the garden and what am I going to do about it?
When I design a garden, I always supply my clients with a maintenance schedule, detailing what I have planted for them, including a link to a google image site so that they can check what it looks like, adding information about flowering time and basic maintenance pointers, and I make every effort to ensure that there is colour throughout the year wherever possible. But one cannot account for the vagaries of weather, soil, feeding habits of owners (their plants, not their barbecue) and other imponderables. So, descending from my soapbox, my favourite plant in July is a fail-safe performer, the ubiquitous Verbena bonariensis.
Please don’t sigh – I know we see it everywhere, but I can remember when it was a novelty and cost a fortune. Now it is widely available and that is all to the good. It is a fabulously versatile, indispensable plant and I urge you to plant it freely and lavishly – as punctuation marks in borders, as a see-through screen, to add height above roses, to create a haze of sleepy purple in the distance, to balance a heavy area of planting. A couple of requests though: please don’t use just one plant at a time or the effect is a bit sparse and twiggy, and also, do please take care when dealing with old plants and cutting them back. If you look at the stems, you will note that they are square in section and when those stems become hardened and tough, the edges become sharp and can inflict injury. This I can affirm from experience – having cut back a stand of Verbena bonariensis I looked at my forearms and was amazed at the lattice of fine sliced cuts. So do wear gloves and long sleeves to avoid injury.
The stems are about 1.5 metres high, with an upright habit meaning that no plant reaches more than 0.5m in width, hence the need to plant in clumps. The flowers appear in May and go on and on and have a singular beauty, rimed with frost and catching the low sun of winter days.
It will grow in a container, though that container would have to be large to balance the height of the plant visually. On reflection I would plant Verbena hastata instead. It is bushier and less rangy.
As a nectar bar the flowers are outstanding, attracting butterflies, bees and hover-flies. We have even had Hummingbird Hawk Moths on those in our Sussex garden. I tend to nip off the top cluster of flowers when it has finished to encourage further flowers lower down the stem.
Ah yes, those long stems. The plant does display a sorry tendency to lean if planted too shallowly or without supportive neighbours, and once it has had a lie down, it will refuse to get up again. There is nothing for it but to cut it back or stake it (and given the slender stems, it seems mad to stake each one). You could certainly add subtle supports to the clump if necessary, but providing the plant is carefully sited, with some tallish planting, such as Dahlia ‘Bishop of Llandaff’, nearby to buffer the wind a little, you shouldn’t have much difficulty with it. Other suitable planting companions are the North American prairie plants including Echinacea and Rudbeckia, and Stipa and Calamagrostis, blond grasses which set off its purple colouring.
They do well in sun, tolerably well in dappled shade, enjoy hot dry sites but dislike too much wet (though I grow mine successfully on clay), and appreciate a dry mulch to protect the crown of the plant through winter. In a good year they can set seed quite happily and in the following spring you will find seedlings displaying longish oval mid-green leaves in pairs which can be lifted and replanted easily. Sometimes it is better to cultivate the seedlings if the parent plant is looking rather woody and exhausted. Buy some plants and collect seed for next year in a paper bag; sow it thinly and transplant seedlings the moment you see the two leaves and before they develop long pale weak stems which render them useless. It is the sort of plant I would hate to be without and one which, even when all around it is limp and green, waves cheerful purple flowers on any breeze it catches.
A postscript to the source of the name: the plant is native to tropical South America, growing widely throughout most of the warm regions from Colombia to Argentina and Chile; the ‘bonariensis’ refers to Buenos Aries.