Controlling the Size of Tansy
I have 3 tansy plants in my garden. They get way too big for the area, but I hate to dig them out. If I keep clipping them to keep them short, will they still bloom?
Tansy tolerates a wide variety of conditions but does a little too well in fertile soils. Do not fertilize this plant unless it shows signs of nutrient deficiency. Spreading a thin layer of compost or other organic matter over the soil surface is usually sufficient. Reducing soil fertility will help reduce the size and slow the spread of tansy. Pruning plants back in late spring may also help. Pruning later in the season can delay or even eliminate bloom. Regular digging and dividing will also help keep the plant size in check. Since these plants are rather assertive and invasive in some areas, you may want to compost the extra plants.