Having spent many of my hours in the garden this summer waging war against an invading army of the twining stems of Hedge Bindweed, Calystegia sepium, I found myself pondering whether other members of the Convolvulaceae family might have more merit in a garden context. A recent day in the Tudor Walled Garden at Osterley House and Garden provided the answer: yes and no!
Although its white trumpet shaped flower is attractive, it is better to prevent Hedge Bindweed flowering in the first place so as to avoid the plant setting and scattering seed. A pernicious perennial weed, it also spreads via a prodigious root system which can colonise mixed borders and, if left unchecked, strangle the plants it scrambles up and around. Where this is allowed to happen, the plant beneath is all but obliterated by a cloak of overlapping heart shaped leaves with prominent drip tips.
I’ve always tried to control this unwelcome tenant in the flower bed to the left of my own garden by removing it by hand, carefully prising the roots from the soil and taking care not to snap off the white fleshy root before extracting its tip. This is easier said than done and I’ve learnt that the roots extend for several metres like an underground rail network with numerous branch lines. When the bed is filled in the growing season with herbaceous specimens, it is impossible to remove the Hedge Bindweed completely and it is just a question of being vigilant and removing it as soon as it emerges. When the plants in the bed have died back in the winter months is the time to dig out as much of this root system as possible.
This summer, for the first time ever, I became so frustrated by this wretched weed penetrating from the neighbouring garden beneath the gravel board at the base of the fence and entwining itself around every plant in this bed, that I resorted to using a chemical control in the form of a herbicide gel. Applying Glyphosate gel to the leaves of the weed is a tricky task because it is imperative to avoid the foliage of other plants. The gel took effect within a few weeks with the treated stems turning brown and the leaves withering. However, in the meantime, a report about the potentially carcinogenic impact of the chemical was widely publicised and my brief flirtation with non-organic gardening came to an abrupt end. When the bindweed was at its worst I nursed a megalomaniac’s fantasy of replacing the fence with a wall with footings deep enough to stop the onslaught, but the thought of the disruption and expense soon put pay to that.
Field Bindweed, Convolvulus arvensis, is another unwelcome member of the bindweed family. It is singled out for special attention when weeding the four large ornamental vegetable beds which make up Osterley’s Tudor Walled Garden. With smaller leaves than is cousin from the hedgerows, its flowers are smaller and pale pink. Its habit is to creep along the soil, supported by another immense root system. I’ve read in a wonderful book, ‘Weeds Weeding and Darwin’ by William Edmonds, that the roots can descend as far as five metres. Like Hedge Bindweed, the upper roots are brittle and because the weed will regenerate from any fragments left in the soil, one of the cohort of garden volunteers is appointed to concentrate on Field Bindweed removal and to extract as much of the root as possible collecting the debris in a separate bucket from those used for other less pernicious weeds. This material is not tipped onto the heap waiting to be composted but is placed in a separate container in which to rot down, lest it contaminate the compost carefully created by the Osterley garden team for use as a mulch throughout the garden in early spring.
It was while working in this spectacular section of the gardens at Osterley a fortnight ago, in a bed where cucumbers and courgettes grow alongside lime green Nicotiana and white spider flowers, Cleome spinosa, that I encountered, trained up an obelisk, the benign and very handsome Ipomaea purpurea ‘Grandpa Ott’. This is a cultivar of Morning Glory, an annual cousin of the unwelcome bindweeds mentioned above. Osterley’s Head Gardener observed that unlike the plant bearing the clear blue flowers of the classic Morning Glory, ‘Grandpa Ott’ does not succumb to powdery mildew. Its deep purple flowers are velvety and prolific. I was assigned the task of gathering the black peppercorn like seeds into an envelope and a few minutes of popping open the fragile dried seedheads yielded a substantial harvest, ready to sow for next year’s display. I am happy to have observed that not all members of the bindweed family are a bind.