Answer: Ferns are relatively easy to dig and divide because the rootmass tends to enlarge as the plants mature. There are two ways of dividing ferns growing outdoors. One is to dig the entire clump and cut through the roots. As long as each division has both roots and foliage, it will grow into a new plant. You can make as many divisions as practical, depending upon the size of the root mass. Or, you can leave the plant where it is growing and simply use your shovel to cut through the top and roots of the plant anywhere along the outside of the clump. Replant the part you took out and fill in the hole with soil. The original plant won't be bothered and the new division can be replanted in a new spot.
If your ferns are in containers, simply unpot, cut as described above except this time you can use a sharp knive. For potted ferns, use regular potting soil. For inground ferns, mix a little compost or peatmoss into the garden soil.
You can divide at any time of the year. Good luck with your ferns!
Q&A Library Searching Tips