Boston Fern


A Boston fern (Nephrolepis exalta) is native to tropical forests and swamp areas around the world. These ferns are especially prevalent in Florida, Mexico, Africa, Central and South America, and Polynesia. Indoor ferns are not that difficult to grow, but they cannot be ignored and are not as forgiving as some other houseplants. High humidity and keeping the soil barely moist are two keys to success. In addition to the Boston fern, the easiest ferns to grow indoors are the Kimberly Queen fern, the Rabbit’s Foot fern, and the Bird’s Nest fern.

Boston Fern Description

The wide- spreading Boston fern, with its long, arching fronds looks beautiful in hanging baskets. The fronds or leaves can be 2-3 feet long and 4-6 inches wide. Each frond has small leaflets (pinnae) on either side of a midrib. The leaflets have slightly serrated edges and a deltoid shape.


Other ferns that belong to the Nephrolepis family and resemble the Boston fern are:

Fluffy Ruffle Fern or Feather Fern that has leathery leaflets with ruffled edges arranged in a double herringbone pattern.

Lace Fern has lacy leaflets arranged in a triple herringbone pattern.

Kimberly Queen Fern or Australian Sword Fern is more compact and neater than a Boston fern, and has erect, narrow, sword- shaped fronds.

                   Kimberly Queen fern, Australian Sword fern, has long, almost erect, sword-shaped, green fronds

Lace Fern                  Fluffy Ruffle Fern          Kimberly Queen Fern

Boston Fern Problems

The special special problems that a Boston fern, and other indoor ferns have, are easily solved if you know what is causing them.

  1. Brown dots on the back side of the fronds: This is not a sign of a disease or plant pest. The brown dots are spores that appear when a fern is mature and healthy. In commercial greenhouses they are used for propagation.
  2. Pale fronds can be an indication of several things. The fern needs to be watered. It is getting too much bright light. The plant needs more fertilizer.
  3. Brown tips and fronds turning yellow indicate lack of sufficient humidity.
  4. Yellow, limp leaves, and rotting stems are caused by too much water and are signs of root damage.
  5. Crispy leaves tell you the plant needs more water.
  6. Tiny, brown shells appearing on the fronds are caused by the plant pest “scale.” Do not confuse scale with harmless spores.


A Boston fern is a clean air plant and helps remove removing formaldehyde from the air. It loves to vacation outside in the shade when the weather is warm but not too hot. Remember to bring it indoors before nighttime temperatures go below 50°F (10°C). A Boston fern is a non-poisonous plant safe to have around small children, cats, dogs, and other pets.

Plant Care


How much light does a Boston fern need: Bright, indirect light helps the plant grow well. Placing a Boston fern in front of a window with a northern exposure allows it to get sufficient light, but not so much that the leaves lose their vibrant green color. Keep the plant out of direct sun.


How much water for a Boston fern: Allow the top 30% of the soil to dry-out before watering. The fronds or leaves may turn a pale green which indicates the fern needs water. Yellow, limp, rotting fronds, especially in the center of a Boston fern, mean the plant is being over-watered. Crispy leaves indicate the fern needs more water. Using “hard water” causes unsightly white marks on the fronds. A Boston fern is more drought-resistant than most ferns, so when in doubt, don’t water.


How to fertilize a Boston fern: Feed monthly when the plant is actively growing with a balanced, liquid fertilizer. Dilute the plant food 1/4 to 1/2 the recommended strength to prevent the ends of the fronds from turning brown due to fertilizer burn.


Best temperature for a Boston fern: Temperature should be 60°-70°F (15.6-21.1°C). Keep all varieties of indoor ferns away from heat sources such as fireplaces and heaters. If the temperature drops below 50°F (10°C) or goes above 90°F (32.2°C), it may damage the leaves.


How much humidity does a Boston fern need: All ferns grow best in high humidity, and a Boston fern is no exception. Unless you live in the tropics, high humidity is rarely found in our homes or offices. If the air is dry and the tips of the fronds are turning brown, try setting your fern on a wet pebble tray. Be sure the fern is sitting on the pebbles and not in the water. You can also put a humidifier in the room, or cluster plants together to create a mini greenhouse effect.


Boston fern plant pests: Aphids, mealy bugs, scale, and spider mites can be a problem. Since pesticides damage fern fronds, spray often with a mild, soapy water solution to prevent and treat pest infestations.


Boston fern plant diseases: These plants are fairly disease resistant. Over- watering, resulting in root rot, is the main problem to keep an eye out for.


Best soil for a Boston fern: Use a good, indoor potting soil mixed with a little extra peat moss to help it drain quickly.

Pot Size

Pot size for a Boston fern: Ferns grow well when root-bound. Repot to the next size pot, and nothing larger, when the roots of the plant have filled the existing pot. When in doubt, do not re-pot. Do not fertilize a Boston fern for several weeks after re-potting.


How to prune a Boston fern: Cut dead fronds off at the base of the stem. Dead leaves on any houseplant should be immediately removed since they drain energy from the plant.


How to propagate a Boston fern: The best and easiest way to propagate is by plant division. Use a sharp, serrated knife to cut the fern root- ball in half or in quarters. Plant the cut sections in small pots only 1″-2″ larger than the root ball. Be sure there are drip holes in the bottom of the pot so excess water can escape. Read more about how to propagate a plant by plant division in the Glossary of the website.

Clean Air Plant

Does a Boston fern clean the air: These ferns are clean air plants and do an excellent job removing formaldehyde from the air.

Poisonous Plant Info

Is a Boston fern Poisonous: Ferns are non-poisonous and are safe to have around small children, cats, dogs, and other pets.


Can I Set My Boston Fern on Top of a Refrigerator in My Very Bright Kitchen?

Ferns do best when the temperature is cool (60°-70°F). The top of a refrigerator is not a good place because it gets too hot.

Why Are the Ends of the Leaves on My Boston Fern From Turning Brown?

The tips of the fronds or leaves on a Boston Fern, and other ferns, may turn brown for several reasons: There is not enough humidity the air. The water you are using contains too much chlorine or fluoride. You are using water that has passed through a softener and is too salty. You are over feeding the plant and the salt in the excess plant food is burning the plant.

What Is the White Sticky Stuff on the Fronds of My Boston Fern? I’m Guessing It’s Mealy Bugs. If It Is, Can I Spray Alcohol on My Fern to Get Rid of Them?

It sounds like you Boston fern has Mealy Bugs. However, since the fronds of a Boston fern are delicate, you have to be careful what you spray on the plant to get rid of the Mealy Bugs. Spray your Boston Fern with warm soapy water or diluted insecticidal soap to get rid of Mealy Bugs. You may have to spray the plant several times to completely get rid of the problem.