Skip to Content

Why Is My Fern Not Growing? (And How To Fix It)

Hey there, plant lovers! Struggling with your ferns and at a loss for what to do? You’ve come to the right place.

Often, the trouble with ferns boils down to root rot or not getting the right kind of light. To give your fern a fighting chance, wait until the top inch of soil is dry before watering it again, and aim to keep the humidity around it at least 65%. Plus, ensure it enjoys 6 hours of bright, indirect sunlight every day.

Root Rot

Fern not growing

Fern not growing due to root rot.

Even as a moisture-loving plant, a fern can still suffer from overwatering. In its natural habitat, ferns thrive under the canopy of large trees, where any excess water is swiftly taken up by the surrounding trees’ roots. This environment ensures the fern’s roots remain in a condition that’s moist, but never soggy.

Not mirroring these natural conditions can lead to trouble. The most common issue is root rot, often caused by excessive watering or pots without drainage holes. Sometimes, the problem is the soil being too dense and wet, or water left sitting in the drip tray after watering.

If root rot takes hold, you’ll notice the fern’s lower fronds turning yellow, while others may start browning at the tips and droop. The roots will feel mushy and emit a bad odor, indicating the plant is in distress and growth has halted.

Here’s what you can do to fix this:

  1. Carefully remove the fern from its pot to check the roots.
  2. Cut away any rotted roots, then clean the remainder with a hydrogen peroxide solution mixed at a ratio of 1:5 with water.
  3. Let the roots air out a bit, and trim away any severely damaged fronds.
  4. Repot the fern in sterile, well-draining soil.
  5. Choose pots with at least four drainage holes, each a quarter-inch wide.
  6. Water the fern only when the top 1-2 inches of soil feel dry to the touch. In winter, let the soil dry out a bit more, about 2-3 inches deep.
  7. Steer clear of a fixed watering schedule and never let water accumulate in the saucer beneath the pot.

Too Dry Air

Another factor that might be stopping your fern from thriving is the lack of sufficient humidity. When the air is too dry, you might notice the fern’s leaf tips turning brown and curling up, or the fronds themselves might start browning. Eventually, the leaves will drop, and you’ll see the plant’s growth significantly slowing down.

Here’s what you can do to fix this:

  1. Keep a humidity meter (hygrometer) close to your fern to check the humidity levels regularly.
  2. Boost humidity by placing a tray with pebbles next to your fern, filled halfway with pebbles and then one-third with water.
  3. Grouping your plants together can also help, as it keeps moisture in the air around them for a longer time.
  4. For the best results, consider using a humidifier.

Dehydration

Just like overwatering, not giving your fern enough water can also halt its growth. As I’ve pointed out before, ferns love moisture and require soil that’s consistently damp. Allowing the soil to completely dry out can cause significant harm to the plant.

Symptoms of underwatering include fronds that start to brown at the tips, with the leaflets following suit, turning brown and wilting. You’ll also notice that the potting soil feels very dry to the touch.

Here’s what you can do to fix this:

  1. Consider getting a soil moisture meter to help monitor the moisture level of the soil.
  2. When you find the top 1 to 2 inches of soil dry, it’s time to water your fern thoroughly, ensuring excess water drains out through the pot’s drainage holes.
  3. Make sure to water the fern deeply rather than just on the surface.

Inadequate Lighting

Fern not growing

Direct sun

Improper lighting is another common reason why ferns struggle to grow. The issue often stems from not getting enough light. Ferns naturally flourish in the dappled shade beneath large trees, where they still receive plenty of bright, filtered sunlight. If your fern is in a room that faces north, it’s likely not getting the light it needs.

Signs that your fern is light-starved include the plant looking tired, with fronds that are softer and droop. The leaflets may sag and turn a lighter shade of green. Without adequate UV light for photosynthesis, the fern’s growth will be sluggish, and it may stretch out seeking light.

Conversely, too much direct sunlight is harmful. Exposure to intense midday sun can cause the leaves to brown and shrivel permanently, impeding normal growth and development.

Here’s what you can do to fix this:

  1. Position your fern in an east-facing room where it will enjoy 3-4 hours of direct morning sunlight followed by bright, indirect light for the rest of the day.
  2. In a south-facing room, keep the fern away from direct sunlight by placing it further back in the room or to the side of the window. The same advice applies to a west-facing room.
  3. Try to avoid north-facing rooms for your fern. If you have no other option, consider supplementing with artificial lighting.
  4. When adjusting the fern’s exposure to sunlight, make the transition slowly.

Too Many Nutrients

Fern not growing

Overfertilization

Sometimes, our efforts to nurture our plants can unintentionally backfire, which is often the case with ferns. Applying too much fertilizer can be detrimental, as over-fertilization can lead to root burn.

If you find yourself fertilizing your fern more than once a month, you might notice brown spots forming on the leaves. Initially, the plant may show a spurt of growth, but this is quickly followed by a period of exhaustion, where growth slows or even halts.

Conversely, not providing enough nutrients can also impede a fern’s growth, particularly for those grown in pots. Unlike ferns growing in the wild, which can source their own nutrients, potted ferns rely entirely on what we provide them.

Here’s what you can do to fix this:

  1. The most effective solution is to repot the fern into fresh soil.
  2. Avoid fertilizing the fern for several months to give it a chance to recover.
  3. After this period, fertilize the fern no more than once every 2-3 months, using a liquid multipurpose fertilizer. Alternatively, slow-release pellets can be used once a year.
  4. It’s best to skip fertilizing during the winter months.

Pests

Fern not growing

Mealybugs

Another potential culprit for your fern’s stunted growth could be pests, particularly spider mites. These critters thrive in dry indoor environments, as they prefer conditions with low moisture. They’re quite tiny and can be hard to spot, but one telltale sign is the fine webbing they spin around the leaves.

Spider mites typically take up residence on the undersides of leaves, feeding on the fern’s sap and causing the leaflets to yellow. This sap-feeding activity generally results in the fern growing more slowly.

Mealybugs are another pest to watch out for. Like spider mites, they feed on the plant’s sap, stalling its growth. Mealybugs, however, are easier to identify because they leave behind white, floury marks on the plant.

Here’s what you can do to fix this:

  1. Inspect your fern closely, using a magnifying glass if necessary, to spot spider mites.
  2. For mealybugs, applying a solution of neem oil or another suitable horticultural oil can be effective.
  3. Increasing the humidity around your fern to at least 60% can help deter spider mites.