I had always wanted to grow tansy because it was said to repel ants. I tried to grow it in Templeton in my herb garden, but the one plant I tried died. When I wanted to redo my Paso Robles front flower beds in June 2013, I managed to get a small tansy plant at the going-out-of-business sale at Fat Cat Farm. This photo shows that plant.
There were actually two plants in the same pot. I planted the smaller one at the very end of this pointed flower bed and the larger one on the other side of the Fruity Germander.
In the past, tansy was used medicinally, but it can be harmful, even fatal. Historically they used it to induce abortions. It can cause poisoning.
It has also been used to repel ants and many kinds of harmful garden beetles, but I've not personally found it very effective against ants. People have also used it in the kitchen as a culinary herb in small amounts, but, again, it can be toxic to ingest too much. I'm not chancing it.
My tansy first flowered a year after I planted it. It normally flowers from July to September. Mine has already stopped blooming this year. How long it blooms may depend on the temperature. This shows my tansy in bloom July 30, 2014. As you can see, some of the leaves are dying back.
This year the plants have had little water. This is how they looked on August 25, 2015. Last September the plants grew tall and then started to die back, leaving a lot of unattractive brown stems that needed to be cut way back. I'm waiting to see if that will also happen this year. I expect it will.
As you can see by following these photos, tansy can be an invasive plant. That's why many people restrain it by planting it in pots. I actually want it to be invasive because I prefer it to the weeds that would otherwise grow in the same place. Nature doesn't like bare ground.
