I don't know where you are located, its a prohibited noxious weed in this state and 2 or 3 (?) others.

Tanacetum vulgare - Germination in less than two weeks at 65-75F . Surface sow seeds, some light may be beneficial to germination. Keep moist.

Common Tansy(Tanacetum vulgare)is a class C weed...Class C Noxious Weeds:
Non-native plants that are already widespread in Washington State. Counties can choose to enforce control, or they can educate residents about controlling these noxious weeds.

Tansy Ragwort(Senecio jacobaea)is a class B weed...Class B Noxious Weeds:
Non-native species that are either absent from or limited in distribution in some portions of the state but very abundant in other areas. The goals are to contain the plants where they are already widespread and prevent their spread into new areas.

It's usually up to the county to decide what type of control is needed for a particular plant, so you need to check with your local Noxious Weed Control Board...

Here is a link that might be useful: WA noxious weed lists

We don't know that the OP is in Washington, actually there is a very limited Z7 area here, most of the state is either Z8 (W) or much lower (E).

We've pulled and mowed a lot of tansy over the years though and finally have the upper hand on the old family farmland - it's not at all good for the cows but they don't seem to know that :)

Oops! Sorry Firestix! My brain picked up on Morz8's area!
If your seeing Tansy at a nursery it's probably T. vulgare. But still, it's a good idea to check with your local weed board.
Morz8, I used to live in W WA, in zone 7 actually(unless it's been changed since 2002), and also had lots of dealings with Tansy Ragwort. The Common Tansy was definitely present, but the county was mainly concerned with the Tansy Ragwort.

Kirk, if you did mean Tansy Ragwort and not common Tansy, the germination requirements are the same. But, do some homework and look it up - Senecio jacobaea, Tansy (tansy with an S) ragwort...this is a noxious weed in many more states than Common Tansy (Tanacetum vulgare)

Noinwi - whether you were 7 or 8, you made quite a climate change...I know it would be a test/challenge of my own gardening skills, I'd have no idea of what to do with your winter ;-)

"Noinwi - whether you were 7 or 8, you made quite a climate change...I know it would be a test/challenge of my own gardening skills, I'd have no idea of what to do with your winter ;-)"

Ha!!Just a lot of hunkering down, staring at the snow and reminding myself we moved here to be closer to family(while dreaming of fresh seafood).

First shipment of copper river salmon flew in yesterday -

I will eat it, but I don't make a point of rushing out to buy it - I don't find it significantly different than fresh caught local sockeye or king salmon other than the crazy swing in price.

Razor clams tonight, we dug this morning ;-)

AAAHHHHHGGGGGG!!!! You're killing me!!!

Intensely jealous of local salmon and razor clams.

Could you be thinking of purple tansy, Phacelia tanacetifolia? Plentiful flowers, nice bee plant, lacy foliage. Takes a little while to sprout, but grows abundantly.

Umm other side of the country in VA. But good thing for me to check... I think your right I'm trying to grow Tansy not Tanzy. I've always been horrible at spelling.

Ahhh yes TanSey.. Ill try again ... I think I have seeds left. I'll also go talk with my local extension office. They were insanely helpful last time I went. Maybe they can tell me how badly it might spread throughout my gardens. Doubt it will be as bad as the catnip tho. I swear the cat is a better gardener than myself. Looking at the seeds (light and wind carry-able)and finding out it grows a rhizome I can see how this might turn quite invasive. SO before it flowers and before it gets out of a pot I will make sure to talk to the extension folks.

In the mean time... Anyone know a better planting option for warding off insects mainly ants from the house? I have heard its great at keeping the ants away. But if its going to take over.. might be more advisable to shot gun with rue, lavender and Artmisia. I know I can get rue going... limited success with lavender, never pulled off Artemsia. I do have a flat with soil no seed, maybe ill fill it with whatever I can come up with and acquire on a pest control plant Google. Starting this late in the season may be the thing that will be the success in some of these I have previously been unable to sprout.

Anyway thanks for your words of warning and bringing it back into my head to go talk to the extension folks.

Here is a link that might be useful: Tansey from one of my seed orderin' places.