Common Boston Fern Problems and How to Handle Them

The Boston Fern, Nephrolepis exaltata ‘Bostoniensis’, is a classic houseplant prized for its lush, feathery fronds. While beautiful, these ferns are particular about their environment and care. Many common problems are signs the plant is communicating a specific need and can be resolved with a few adjustments.

Yellowing or Browning Fronds

Yellowing leaves, especially on lower fronds, often result from overwatering or intense, direct sunlight. Boston Ferns prefer consistently moist soil, but soggy conditions suffocate the roots. To check moisture, insert a finger about an inch into the soil; if it feels damp, wait to water.

Fronds that become brown and crispy at the tips point to a lack of moisture, either from underwatering or low ambient humidity. These ferns are native to tropical environments and thrive in humidity levels above 50%. You can increase humidity by misting the plant, placing its pot on a tray with pebbles and water, or using a room humidifier.

An accumulation of salts from fertilizer can also cause brown tips. If you suspect this, flush the soil by watering the plant thoroughly and letting the excess drain completely. Trimming away discolored fronds allows the plant to direct energy toward new growth and improves its appearance.

Excessive Leaf Shedding

It is natural for a Boston Fern to shed some leaflets from older, lower fronds as they age. This is a normal part of the plant’s life cycle and makes way for new growth.

A sudden increase in leaf drop, however, signals that the plant is experiencing stress. A primary trigger for this is environmental shock from abrupt changes. Moving the plant to a new location or placing it near a drafty window or heating vent can cause it to drop leaves.

Chronic underwatering is another contributor to shedding, causing fronds to become dry and crispy. The fern sheds leaflets as a survival mechanism to conserve water. Maintaining consistent soil moisture and a stable environment will reduce the stress that leads to excessive shedding, allowing your fern to remain full and lush.

Common Pests and Diseases

Common pests include spider mites and mealybugs, which thrive in warm, dry indoor conditions. Spider mites are tiny and leave fine, silk-like webbing on the undersides of leaves. Mealybugs appear as small, white, cottony masses where fronds meet the stem. For both pests, wipe the leaves with a damp cloth or treat the plant with insecticidal soap or neem oil.

The primary disease threat is root rot, a consequence of overwatering and poor drainage. When soil remains waterlogged, fungi can attack the roots, causing them to turn brown, mushy, and emit a foul odor. If you suspect root rot, remove the fern from its pot and inspect the roots, trimming away any that are black or soft with sterilized scissors. Repot the fern in fresh, well-draining soil and a clean pot with adequate drainage holes.

Stunted or Leggy Growth

If fronds appear stretched out and sparse, the plant is likely “leggy,” a symptom of insufficient light. The fern is stretching its fronds to reach for a light source. To resolve this, move the plant to a location with bright, indirect sunlight, such as near a north or east-facing window.

If your fern has stopped growing, it may be root-bound. A plant becomes root-bound when its roots have filled the pot, often circling the bottom or growing out of the drainage holes. To check, gently slide the plant out of its pot to inspect the root ball. If it is root-bound, repot it in the spring into a slightly larger container to provide room for new growth.

A lack of nutrients can also cause stunted growth. This can be addressed with a diluted, balanced liquid fertilizer during the spring and summer growing season.