Bindweed

Whilst bindweed is a ‘pain in the proverbial’ for gardeners, I thought it was worth writing a short piece about why I think it’s an incredible plant, despite being rather challenging.

There are two types of bindweed both of which are ‘pernicious’ perennials.

Hedge Bindweed or Bellbind (Calystegia sepium)

Hedge bindweed has large pure white trumpet shaped flowers and its heart shaped foliage is often seen twining up and around any plant, post, tree, and hedge, choking everything in its path.

Field Bindweed (Convolvulus arvensis)

Field bindweed has much smaller, pretty pink and white candy stripped trumpet shaped flowers, very fitting for a seaside allotment. It has very similar foliage to the hedge bindweed. As the name suggests, this bindweed grows along the ground, sending out shoots several metres long.

Of course we inherited both types at the allotment, along with brambles, dock and couch weed! It has certainly been a challenge to get this particular weed under control, and the reality is, we may never get rid of it completely.

When we acquired the orchard plot, much of it was covered with carpet and underlay. We were pleased because we thought this would make this plot much easier to clear and dig over. However, underneath the carpet we found what looked like masses of cables. These were in fact bindweed roots, and these were just the bits we could see.

So why is bindweed such an impressive weed? Simply, it’s incredibly resilient. Over the years it has evolved to survive the harshest of conditions and it seems to be indestructible.

In it’s first year the bindweed produces a tap root that can descend 1.2 metres. In two and half years the tap root can descend down to 4 or 5 metres. So even in the toughest drought and intensely cold conditions, when many other plant species are struggling to survive, these plants can seek water to survive.

Additionally, the root system is extensive. The plant produces vast ‘nests, of zigzagging white rhizomes, these lay around 30cm below the soil surface. In the plants first season this root network may expand as much as 3 metres in diameter. Additionally, this root system can produce as many as 25 ‘daughter’ plants, creating it’s own ‘colony’ of bindweed plants. The roots of older plants can spread as wide as 6 metres in diameter. Imagine how massive the colony of bindweed will be by then!

The roots have interior buds that develop into shoots, stolons or remain dormant. These buds are most active during the spring and summer when temperatures rise above 57F.

Once active, the shoots are ready to start breaking up through the soil and get twining. The stolons, otherwise known as stems or roots, grow at surface level or just below surface level. They zoom across the surface, several metres at a time. When they hit an obstacle such as another plant, tree or fence, they push down and generate a new root system. A new shoot appears ready to twirl around the new climbing opportunity. It’s usual for another 2 or 3 shoots to appear, eventually covering the new structure. Bindweed will literally smother anything that comes into its path as it searches for light.

The other problem arises when digging out the root. By leaving even the smallest fragment behind in the soil the plant will regenerate and grow into a new plant. Using a rotavator on a plot with bindweed is not a great idea.

Now for it’s flowers. Not only are they rather beautiful, the plant remains in flower for 4 months, blooming from May through to September. This long flowering period ensures a large majority of the flowers are cross-pollinated. Each flower produces a tear-shaped, light brown fruit, which contains between 1 to 4 seeds. On average each plant can produce between 300 to 600 seeds in a year. What’s worse, these seeds can lay dormant in the soil and remain viable for up to 20 to 30 years.

Whilst really difficult to do, it’s important to eradicate bindweed on allotments because the chemicals secreted by the root system can interfere with the germination of some seeds. The most effective way to control bindweed is to painstakingly remove it by hand. Winter, when the plant is dormant, is the best time to try and remove bindweed roots.

Don’t put the roots on to the compost heap, they will grow. Either let them dry out and burn them or place in a bucket of water and leave for a very long time. The roots are full of nutrients and will eventually rot down and form a decent compost.

Whilst bindweed is NOT welcome at the allotment I have to marvel at it’s ability to survive.