Answer: Casoron is a pre-emergent herbicide and is very effective for keeping weed seeds from germinating. It is generally safe to use around woody ornamentals but herbaceous ornamentals can be adversely affected, especially if Casoron is applied in amounts greater than recommended on the label. Casoron degrades in the presence of sunlight and water; it degrades faster in sandy soil, slower in clayey soil. Its life can be anywhere from 6-months to 3 years, depending upon the situation. Once the soil is contaminated, there isn't any practical way to remove it except to allow it to degrade naturally. I can only recommend you contact your gardening contractor and request replacement plants (but don't plant them right away!) Best wishes with your landscape!
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