If use a pesticide to rid the bidweed/morning glory around my roses, will the roses, flox and peonies survive? I can’t remember having to use a pesticide, but I’ve fallen behind in cleaning up the garden. I could get help, as an option, but there is some satisfaction, despite the little I can do as I wait for surgery. If I paid for help, the yard might turn into a putting green on artificial turf. I can stretch out my activities for a couple of months for the small area of 400 square feet. Getting fatigued is a good remedy for insomnia too, since I do the cleanup at night. I just wish the absent neighbour would do a hard prune of their invasive tree more often since it takes 20% of my gardening time to wrestle with their unattended tree.The only consolation is my temperamental string trimmer is more co-operative this year.
There are two species of bindweed – hedge bindweed (Convolvulus sepium L.) and field bindweed (Convolvulus arvensis L.). They are very similar in appearance and growth habit and they are very difficult to get rid of. I have copied the following paragraph from an article on the Ontario Ministry of Agriculture website. It makes depressing reading:
As soon as bindweed is established in a new area, an infestation can spread locally by roots and rhizomes. After the first growing season, the roots of a single plant may cover an area 3 m in diameter and produce up to 25 daughter plants. Roots of older plants may occupy an area 6 m in diameter and several metres in depth if soil is quite permeable. The roots possess interior buds that can develop into either shoots or roots or remain dormant. Rhizomes and attached lateral roots can survive if severed from the primary root, and roots that are fragmented by cultivation will regenerate new plants from those portions containing buds. The extensive root network stores a large quantity of carbohydrates which provide the energy for the regrowth of shoots and roots from root buds even several years after continuous removal of top growth. Even 3-week-old seedlings are able to regenerate from the root if the top is removed.
University of California Agriculture and Natural Resources gives a few more details. Details about growth habit are important as they let you know what you are up against.
Roots capable of budding are found as deep as 14 ft. Fragments of vertical roots and rhizomes as short as 2 inches can form new plants. Lateral roots serve another important function. About 15-30 inches from the parent plant, a lateral often turns downwards, becoming a secondary vertical root, and sends out both roots and shoots from the turning point. Round, smooth 1/4 inch capsules have 1-4 seeds. Seed that is 60 years old is viable.
The best way to control bindweed is to cut off stems at ground level, then roots will not get carbohydrates from photosynthesis. In this way the roots will gradually starve to death and the plant will die. Also cut off the flowers before they produce seeds. Landscape fabrics such as polypropylene and polyester and other mulches such as black plastic or cardboard have been effective for bindweed control if no light is allowed to reach the soil and the plant. The edges of the fabric must overlap so that the bindweed stems can’t grow between the sheets and into the light. A landscape fabric placed over soil then covered with bark or other plant-derived product (e.g., organic matter) or rock will likely keep field bindweed from emerging. It might take more than 3 years of light exclusion before the bindweed dies. Once landscape fabric or other mulch is removed, new bindweed plants might germinate from seed in the soil.
I can’t recommend the use of herbicides because they are controlled substances for the home gardener. Often roundup (glyphosate) is used in agricultural fields and even that requires correct timing as to growth stage and multiple applications to work. I know someone with a rental property in downtown Toronto. It had japanese knotweed in the backyard and 5 adjacent yards last summer. The method used to control this plant is the same as for bindweed, cut off at ground level and prevent from flowering. Because it was a rental property and she couldn’t rely on her tenants to cut the knotweed regularly, she painted the leaves with roundup; painted not sprayed. There was a mature lilac close by these plants and this year, that lilac is dead. Also japanese knotwood is coming up, although in greatly reduced numbers. Nevertheless, if not repeatedly cut down, the knotweed will return as much as before.