It took a long time for me to find tansy to use as a companion plant under caning fruit, grape trellises, roses, and orchard trees. It is supposed to repel borers, ants, flies, fleas, and squash, cucumber and Japanese beetles! They supposedly used it in place of black pepper for cooking in the old days, too. It is high in potassium and is considered a good addition to compost piles. All this per "Carrots Love Tomatoes" by Louise Riotte, page 164 ( http://davesgarden.com/products/gbw/c/417/ )
Yep, it's in and around and all over my roses, too, among other things. Sometimes the scent is so strong it almost repels me, as well.
We were in the middle of a drought all summer...and still no rain. Everything in my garden died back, except the tansy. It got a little crunchy and I finally cut it back nearly to the ground the end of August...yet now it's about a foot tall. No rain and one light frost, I'm wondering if it might even bloom again for Thanksgiving.
Thanks for the words and for the link!