Symptoms of a Boston Fern Going Awry

Boston ferns are a popular choice of houseplant; they can add charm to any home and especially flourish during the spring and summer months. Boston fern do require specific care and attention, and neglecting any of several measures can create any of the following problems that need prompt attention.


Boston ferns require a level of humidity that is not naturally found in the home. It is recommended to maintain your fern at forty to fifty percent humidity. Those that go for more than a short time in too dry an environment will develop what is know as frond greying: a dull, unsightly coloring of the leaves. If left untreated, this problem can turn into as condition called runner burn, named for the fern's long stems that carry water throughout the leaves. Runner burn causes brown and dry leaves that quickly die and fall off. Another symptom of dehydration in ferns is leaves that turn white rather than grey or brown. This is a sign that the roots have dried out, and it will be necessary to soak them directly in distilled water. 

Many fern owners have found that frond greying and runner burn can be prevented by getting in the habit by always keeping the fern's potting soil moist. For those who live in drier climates, particularly those with harsh winters and summers, invest in a small humidifier for your Boston fern. Another option that works well is to mist the fronds daily with a spray bottle.

Deficient Fertilizer

Boston ferns also require regular fertilizer mixed with their potting soil. During the growing season of spring and summer, it is advised to add new fertilizer every second week. Boston ferns can be fed fertilizer once per month during the winter months. Those that are not getting adequate fertilizer will start to loose color in their leaves and will also start to sag. Be sure to buy quality fertilizer for your Boston fern; some types have been found not to have adequate nutrients.

Pests and Fungi

Spider mites and mealybugs are two species of pest that are attracted to the Boston fern. Evidence of them includes small holes eaten in the leaves, yellowing or greying leaves, and sometimes brown scabs or scales on the runner stems. It is not recommended to use harsh pesticides to take care of this problem; these can further damage the fronds and stems. Look for remedies with green/natural ingredients, and your local plant nursery should be able to recommend specific ones.

Boston ferns can also develop one of a few types of fungus, most commonly rhizoctonia aerial blight and pythium root rot. Symptoms of pythium root rot include fronds turning an unusual orange-yellow color, blackening of the stems close to the soil, and rapid dying of entire fronds. This fungus is actually caused by over-watering; potting soil that is too saturated and left to stand is a rich environment for the pythium spores to develop. Rhizoctonia aerial blight, also known as leaf spot, is evidenced by brown spots and web-like patterns through the leaves and stems of your Boston fern. This is often a result of excess water combined with the fern being placed in an area that is too hot.