Boston ferns are fabulously popular houseplants. Hardy in USDA zones 9 to 11, they are kept indoors in pots in most regions. Capable of growing 3 feet (1 m.) high and 4 feet (1 m.) wide, Boston ferns can brighten any room with their lush green foliage. That’s why it can be so disheartening to see your vibrant green fern fronds turning black or brown. Keep reading to learn what causes a Boston fern with black fronds, and what to do about it.
Boston Fern Fronds Turning Black Isn’t Always Bad
There is one case in which a Boston fern with black fronds is perfectly natural, and it’s good to be able to spot it. You may see small black spots on the undersides of your fern’s leaves, lined up in regular rows. These spots are spores, and they’re the fern’s way of reproducing. Eventually, the spores will drop to the soil below and grow into reproductive structures. If you see these spots, don’t take any action! It’s a sign that your fern is healthy. Your fern will also experience some natural browning as it ages. As new growth emerges, the oldest leaves at the bottom of the fern will wither and turn brown to black to make way for new growth. This is totally normal. Cut away the discolored leaves to keep the plant looking fresh.
When Boston Fern Fronds Turning Black is Not Good
Boston fern fronds turning brown or black may also signal trouble, however. If your fern’s leaves are suffering from brown or black spots or stripes, there may be nematodes in the soil. Add lots of compost to the soil-- this will encourage the growth of beneficial fungi that should destroy the nematodes. If the infestation is bad, remove any infected plants. Small, but spreading, soft brown to black spots with an unpleasant odor are most likely a sign of bacterial soft rot. Destroy any infected plants. Leaf tip burn manifests as browning and withering tips on fronds and leaves. Destroy any infected plants. Rhizoctonia Blight appears as irregular brownish black spots that start near the crown of the fern but spread very rapidly. Spray with fungicide.
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Boston Fern Diseases: Caring For Unhealthy Boston FernsBoston ferns require adequate sunlight, water and nutrients to thrive, and good cultural practices help keep them healthy. If it doesn't get the best care - or even if it does - it may be attacked by diseases. Click here to learn more.
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Boston Fern Light Conditions: How Much Light Does A Boston Fern NeedLight requirements for Boston ferns is a critical aspect of successful growing. Read this article to learn about Boston fern light needs, including Boston fern light conditions. Click here for more information.
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Boston Fern Leaf Drop: Why Leaflets Fall From Boston Fern PlantsBoston ferns are great indoor accent plants, but they've earned a reputation for being difficult to care for due to frequent yellowing, drying or dropping of their leaves once inside. Learn how to prevent or halt Boston fern leaf drop in this informative article.
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Boston Fern Turning Brown: Treating Brown Fronds On Boston Fern PlantThe Boston fern plant requires plenty of humidity and low light to prevent the fern from turning brown. If you have a Boston fern with brown leaves, it might be cultural or simply having the wrong site for the plant. Learn more in this article.
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Root Nodules On Boston Fern: What Are The Balls On Roots Of Fern PlantsBoston fern, also known as sword fern, is a dependable plant with masses of long, graceful fronds. One might also notice root nodules on Boston fern plants, of which this article explores. Click here for more information.
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