Boston Fern Diseases: Caring For Unhealthy Boston Ferns


Amy Draiss
Boston ferns (Nephrolepis exaltata ‘Bostoniensis') are old-fashioned ferns with beautiful arching fronds. They require adequate sunlight, water and nutrients to thrive, and good cultural practices help keep your fern healthy. If your fern doesn’t get the best care – or even if it does – it may be attacked by Boston fern diseases. Read on to learn more about diseases of Boston fern plants.
Common Boston Fern Problems
If you fail to water your potted fern appropriately, over or under irrigation can lead to unhealthy Boston ferns. Most fern instructions advise you to keep the soil constantly moist. But this is not the same as allowing the soil to be wet or the plant to become water-logged. To avoid issues with Boston ferns, water the plant thoroughly when the top of the soil is dry. Keep watering until it leaks from the drain holes in the bottom of the pot. Do not water again until the soil surface is dry. Failure to water sufficiently can lead to graying, one of the most common Boston fern problems. Graying is often the result of drought conditions. You’ll know if your plant has this condition when the leaves turn gray and the plant may seem to stop growing. Increasing irrigation should resolve this. Although many gardeners consider tropical ferns low-light plants, Boston ferns need adequate light. If they do not get a medium amount of light – at least two hours of indirect light all year round – their fronds become long and pendulous. This is termed weak frond and is resolved by increasing light.
Boston Fern Diseases
If the fronds of your Boston fern turn gray and you’ve been watering properly, a disease to consider next is Pythium root rot. The fronds can also wilt or grow stunted. To confirm root rot, look at the roots of your unhealthy Boston ferns. If they are brown and stunted, it is likely root rot. The best way to prevent a Boston fern from getting root rot is to buy disease-free plants and pathogen free potting soil. You can also check in your garden store for chemicals that control this disease in Boston ferns. These tips are also appropriate for preventing and treating other Boston fern diseases such as Rhizoctonia aerial blight. In blight, dark lesions develop rapidly on the foliage and roots. Unchecked, the entire plant is eventually covered with the pathogen’s brown web-like mycelium. If you opt to use chemicals to treat this disease, treat the soil as well.
Gardening tips, videos, info and more delivered right to your inbox!
Sign up for the Gardening Know How newsletter today and receive a free copy of our e-book "How to Grow Delicious Tomatoes".

Teo Spengler is a master gardener and a docent at the San Francisco Botanical Garden, where she hosts public tours. She has studied horticulture and written about nature, trees, plants, and gardening for more than two decades. Her extended family includes some 30 houseplants and hundreds of outdoor plants, including 250 trees, which are her main passion. Spengler currently splits her life between San Francisco and the French Basque Country, though she was raised in Alaska, giving her experience of gardening in a range of climates.
- Amy DraissDigital Community Manager
-
Which Invasive Shrubs Should You Avoid Growing? Plus, Best Natives To Plant Instead
Certain plants may look lovely but they can wreak havoc to local areas and native wildlife. Here are the key invasive shrubs to avoid – with recommendations on gorgeous native alternatives to try
-
What Not To Plant With Tomatoes: 8 Bad Neighbors That Could Ruin Your Harvest
Not all companion plants are beneficial – some can sabotage your tomatoes. Find out which ones to keep at a safe distance in the garden.
-
Want To Know How To Make A Spider Plant Bushier? 4 Secrets For Lush & Bushy Spiders
Are you looking for ways to make your spider plant look bigger or more dramatic? Follow these quick and easy tips on how to make a spider plant bushier
-
Best Spider Plant Soil – Complete Soil Guide And Expert Tips For Keeping Plants Happy
Spider plants are fun and easy plants to grow, but what is the best soil for a spider plant? Selecting the right soil is important so they can thrive.
-
Help, My Snake Plant Is Mushy! Advice For Root Rot In Snake Plants
Snake plants are hardy houseplants, but they can be susceptible to root rot. Learn how to prevent and treat this common snake plant problem.
-
How To Grow A Hanging Spider Plant – For An Elegant Indoor Or Outdoor Display
Of all the beautiful baskets we see, the hanging spider plant is probably the easiest to grow. Let your hanging basket spill over with little spider plantlets!
-
How To Care For A Variegated Spider Plant – Plus, Unique Varieties To Try
Variegated spider plants and their streaks of green and cream tones bring interest and light to an indoor room, and will elevate your houseplant collection.
-
How Often Should You Water A Spider Plant? Tips To Keep Spider Plants Happy And Healthy
Spider plants are hardy and easy to grow, but they do need proper watering to thrive. Read our tips on how often to water your spider plants.
-
Snake Plant Getting Enough Light? Understanding Light Requirements And How To Adjust
Snake plant light requirements aren’t as stringent as for some houseplants, but the right lighting is important for their growth and well-being.
-
Feeding Houseplants: How And When To Fertilize Indoor Plants Like A Pro!
Container-based houseplants have specific feeding needs over and above plants grown in the ground. Here’s how and when to fertilize indoor plants the right way