Hi, Sorry this answer was delayed, but our Garden Doctor service was down for repairs during the month of November. I would leave your mum plant alone if it's flopping late in the year. The key is to dig and divide it when it first emerges in the spring. Also, pinch the growing tips of each stem after the plant gets about 6 inches tall. Then, again, a few weeks later. By being pinched twice early in the season it will promote bushier growth and help keep the plants standing tall when they are in flowr.