Bindweed - Convolvulus arvensis - is one of our top ten garden weed pests. It need not be so, for it is quite simple to kill. However, it does take a bit of patience and above all - willpower (neither of which can be bought in handy ready to use spray guns!).
One big problem with killing or controlling Bindweed is the fact that its habit of growth makes it difficult to isolate in order to use a chemical weedkiller. It is often to be found twining its way through shrubs, hedges and other garden plants. This makes the application of a suitable weedkiller to the foliage rather difficult, for the same weedkiller will also kill - or at least severely harm - the cultivated plants that in comes into contact with.
Bindweed can also be found in waste ground or neglected allotment gardens. It seems to be happy in most soil types, and whilst it is a herbaceous plant (dies down each winter) it still comes back the following year - even more vigorous after it's winter rest!
This weed usually has white flowers, but there are also some with light pink flowers. There are also some cultivated forms with flowers ranging from gaudy pink through to red.
Most attempts to kill Bindweed by using weedkillers - Glyphosate is the best - fail miserably because of the methods used in spraying. Glyphosate - which is sold under a variety of brand names such as Roundup and Problem Weed Killer etc - needs to be applied to the foliage of the plant when it is in active growth. 'Active Growth' is often described as being when the weed is in flower - such as that in the image above. However, as long as the plant is growing strongly - usually at any time at the start of summer - or even in late spring - then it can be killed with Glyphosate.
The important thing to remember is that it will probably take two or even three applications throughout the growing season to kill the bindweed off altogether. Once it has been treated with Glyphosate, just leave it alone so that the chemical can then work its way down into the root system. This can take up to three weeks, although the first effects can normally be seen after a few days or a week. Don't be tempted to pull the wretched thing out at this stage. Allow it to die down to ground level - giving it time for the Glyphosate to get down into the roots.
If it is well and truly entrenched in and around valuable plants, then use the Glyphosate Gel, which can be painted on individual leaves (as many as you can) and this will do the job of killing the bindweed. This method will probably take longer than spraying, but it is often the only chemical course of action.
It is important not to get the weedkiller on the foliage of your cultivated plants. If this happens accidentally, then was it off as soon as possible with water.
There are all sorts of 'tricks' that can be used to isolate the weeds from your plants - unwinding it; dragging it up through a cardboard tube and then spraying inside the tube; using a sheet of card to isolate other plants.
Do NOT spray on a windy day!
Bindweed can be cultivated out of most areas of the garden. But it takes persistence for it is virtually impossible to fully eradicate by digging the white fleshy roots out - although this may be possible with areas such as allotments during winter months. Any portion of root broken off during the digging process will mean a new plant in the spring! However, if you keep a close watch, then stray new plants can normally be pulled out gently by hand - bringing the root out with the plant.
Bindweed can be effectively controlled in herbaceous and shrub borders, simply by pulling the weeds out regularly. Do it gently and you will bring much of the root system out with the weed. Yes - it will shoot up again, but in this case you do not need to allow them to get into 'active growth'. Just keep on top of the problem with a weekly pulling session. Eventually, the roots will be totally starved of their food resources - which come from the foliage growth - and you will have the problem at least well under control, and if you are really diligent, then completely eradicated.
Covering an infested area with a black plastic sheet may be an option in some circumstances, but you will need the sheet to remain for twelve months, and you will also find the bindweed spreading under the sheet - through to the edges - where it will send up new growth, which in turn will send food supplies back to the embattled roots under the sheet!