Answer: Some varieties of pampas grass are considered invasive because they spread seed with abandon. The white plumes they develop can set seeds and those seeds can travel on the wind to far away places. While part of the beauty of pampas grass are those white plumes, you can keep your plants from being invasive by simply cutting off the plumes when they begin to change color from white to a yellowish white, thereby removing the seeds before they can spread. Most of the newer varieties of pampas grass will not develop viable seeds, but there's no way of knowing whether yours is a newer variety. With that said, if you decide to remove the plants completely you can cut them down to almost soil level and apply Round Up or Brush B Gone to the stumps of the plant. This will kill the roots and you can either leave them alone to decompose or you can dig them out, roots and all.
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