This is California’s No. 1 garden thug

How to contain bindweed, the worst weed in state

By Debbie Arrington

This bindwind seedling is about 3 weeks old. 

Drought-resistant and resilient, this flowering vine can withstand just about anything and still thrive.  Its pearl white blooms look very similar to its enchanting cottage cousin, the morning glory. That deception can charm its way into garden acceptance, for at least a little while.

By then, it’s too late. Bindweed has wound its way into another garden to create havoc, choking plants and basically taking over.  It’s the worst garden thug in California.

Bindweed (Convolvulus arvensis) is so ubiquitous that many gardeners assume it’s a California wildflower.  Originally from Eurasia, bindweed was first seen in San Diego in 1884, according to the University of California. It quickly spread throughout the state. By the 1920s, bindweed was declared the worst weed in California.

Almost a century later, it’s not much better. Government agencies, agricultural districts and parks departments have all declared zero bindweed tolerance. Yet it keeps coming back.

That’s due to bindweed’s many attributes for survival. It’s a hardy perennial, meaning the top may die back, but the rhizomes will send out new shoots as needed. Its roots can reach 20 feet deep. It also sends out lateral roots several feet in each direction. Those laterals send down vertical roots and start new plants.  One plant can spread 10 feet in every direction in just one season.

Bindwind blooms in a jasmine plant that it is choking. 

That massive root system is key to its drought resistance – and why bindweed is so difficult to control. UC research found that one acre of bindweed can produce 5 tons of roots and rhizome. Every 2-inch fragment of root or rhizome is capable of producing another plant.

And then there are the seeds: on average, 550 per plant. Those seeds can stay viable in the soil for 60 years! Digging up soil to get rid of bindweed roots can bring long-dormant seeds to the surface to sprout.

How to control bindweed? Be just as persistent.  Pull seedlings as soon as they appear. The seedlings form a perennial rhizome after three or four weeks (and will be much harder to eliminate).

If you see flowers, definitely pull  those plants before they set seed, further compounding problems.

When weeding, use a hoe and whack the plant about an inch below the plant’s crown. That leaves the weed’s roots and seeds below soil level. Repeat every two to three weeks as the roots resprout. Eventually, the plant is deprived of energy and starts to give up.

Landscape fabric or cardboard topped by mulch can eventually suffocate bindweed. It deprives the plant of light and energy and will kill the roots, too – after about three years. But bindweed is very opportunistic; it will work its way through any hole in the fabric or opening in the mulch.

As for chemical controls, Roundup (glyphosate) can slow bindweed down. To be most effective, the herbicide needs to be hand-painted onto the vine’s leaves, then takes about three weeks to kill the vine. But the herbicide can damage shrubs (especially roses) or other nearby plants, so use precautions such as shielding them from possible exposure.

For more information on bindweed and possible control, check out the UC Integrated Pest Management tips at http://ipm.ucanr.edu/PMG/PESTNOTES/pn7462.html.