Answer: You would need to dig down deep enough to remove the entire root system of the hostas and the actual bulbs as well. Hostas are usually not too difficult to dig out, and most of the small bulbs are within the top six inches of soil.
Alternatively, you could spray with an herbicide containing glyphosate. This is a non-selective herbicide that is absorbed by the foliage and then is translocated to the roots where it kills the plant. Be sure to carefully read and follow all of the label instructions.
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