Garden Tales: Crown Vetch
Crown vetch is a prime example of how good intentions and the best laid plans often go astray. Crown vetch or (Coronilla varia) is an attractive plant and three or four of them add colour, shape and beauty to the garden. However, that beauty has a sinister aspect.
Crown vetch was originally introduced for use on low maintenance areas such as slopes around commercial or public buildings, highway and/or driveway slopes, lawn areas too steep for safe mowing and slopes associated with many recreational facilities or parks.
Crown vetch has a creeping stem reaching 3 to 5 dm in length and is a member of the pea family.
The compound leaves range from 5 to 10 cm in length and have nine to twenty-five leaflets. Leaflets are one to two cm long, oblong with persistent stipules.
Five to twenty pea-like flowers are umbellate and borne on a stalk 5 to 15 cm long. Flower color is somewhat variable from pink, rose, or lilac. Flowers appear in late May-August.
There are reports that mowing or cutting down crown vetch three or four times a season can do the plants cosniderable harm, but it remains doubtful if this method would get rid of them all and as long as there is life, this one will come back.
Another organic method that may get rid of this invasive plant is the use of thick black plastic. In early spring, cover the entire area were the Crown vetch is growing with a sheet or sheets of a thick black plastic, making sure no light gets through. Leave the in place for 60 days, remove the plastic, add some compost and mulch heavily, I would let this area sit fallow for a season and then plant.
It is essential to keep an eye out for this one may sneak back. The best chance you have of defeating this aggressive plant is to keep an eye out for its early appearance in yoru garden or lawn and act. Even then you may find it coming back the following season, however, if you tackle the problem early enough, it is possible it will not take over and become a serious threat to your garden.
The Crown vetch story is a good reminder that even though introducing a non-native species into an ecosystem because it can serve a purpose is not necessarily a good idea. We really do not know what will happen as time passes and the plant adapts to its new home.