Native Plants

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Friday - July 18, 2008

From: Rico, CO
Region: Rocky Mountain
Topic: Invasive Plants
Title: Control of white clover (Trifolium repens)
Answered by: Nan Hampton

QUESTION:

our yard was remediated by ARCO in Rico Colorado. they brought in soil that must have been from clover fields. the soil produces tense low growing and fast growing clover with white flowers. it is invasive and is destroying our wildflowers that are natural. how does one get rid of this and allow the wildflwers that are native to flourish? in one year it has taken over large areas that used to be native. thank you. kim

ANSWER:

This sounds like Trifolium repens (white clover), a native of Europe. It is considered a weed plant in many parts of North America. However, it's still recommended as a pasture plant in association with grasses, even though it can cause gastric distress in livestock if eaten in large quantities. It has its good points, nevertheless, in that it fixes nitrogen from the atmosphere and enriches the soil for other plants when it dies.

You can read the Clover Management Guidelines from University of California Davis and learn that the best means of controlling it is by hand-pulling or hoeing it. I know this doesn't sound like a lot of fun, but there are no herbicides that will kill only the clover and not your wildflowers. Soil solarization, which is an effective way to kill grasses and other weeds, is apparently not very effective for clover since it doesn't kill seeds as well as the plants—white clover has a hard seed coat that is resistant to high temperatures. Heavy mulching in flower beds can keep the population of clover under control; but if you are dealing with a meadow-like yard, this isn't going to be a practical way to approach the problem. If you add native grasses to your wildflower mix, they can help in outcompeting the clover by growing tall and shading the clover plants. Please read our article, Meadow Gardening, for more information.