Lift the Boston fern to inspect the root ball when roots are congested, circle the pot, emerge through drainage holes or crowd the roots enough to make drainage unreliable. Do not use a calendar alone.
Boston fern repotting: check roots before changing pots
Lift the Boston fern to check the root ball before repotting. Crowded roots, roots circling the pot or roots emerging from holes matter more than the calendar.
Check the roots, mix and drainage
When to repot
Repot in spring as active growth begins. Avoid leaving fresh wet potting mix around a slow-growing fern in fall or winter.
Use the smallest practical size increase
Choosing the next pot
If the roots need more room, move to a container no more than one third larger. For a small pot, about 1 to 2 inches (2.5 to 5 cm) more width and depth is the guide.
Move the rootball without unnecessary damage
How to repot
Use fresh peat-free potting mix that holds water while draining freely, keep the fern at its existing planting level, and trim only soft or rotted roots found during inspection.
Keep light, water and support steady
After repotting
Water the potting mix through after repotting and let excess drain. Return the fern to bright filtered light with humid air and a root zone that stays damp but not saturated.
Sources
- Royal Horticultural SocietyHow to Grow > Cultivation; soil; moisture; container
- Royal Horticultural SocietyWhy repot; When; Potting on; Aftercare