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How to Care For a Boston Fern (Nephrolepis Exaltata)

Last Updated on December 4, 2022 by Plant Mom Care

Nephrolepis exaltata or Boston fern, a species of ferns from the Lomariopsidaceae family, is indigenous to tropical regions throughout the world. It is generally found in humid swamps and forests, particularly in northern parts of South & Central America, Florida, the Caribbean, Oceania, and Africa. 

This evergreen plant grows to as high as 16–35 inches and sometimes up to 4 feet 11 inches high. The fronds are 20–98 inches long and 2.4–5.9 inches broad, with alternate slightly serrated leaflets on both sides of the midrib of 0.79–3.15 inches long.

The plant can grow as an epiphyte as well as terrestrially. The spores are wrinkled and wart-like. The plant also forms a slim and tuberous underground rhizome.

boston fern plant care guide from plant mom care

These ferns were popular houseplants in the Victorian era of the 1800s. One of the unique aspects of this fern is that they always appear to be mutating and changing, therefore always producing “new” varieties. 


Boston Fern Light Requirements

Lighting for this fern plant should be practical. The plant can handle full sun for some time but it also requires shaded areas. For this plant to be happy and healthy, you must grow it in a fairly bright area under indirect light and avoid harsh sunlight as this plant doesn’t like full sunlight.


Boston Fern Watering

These plants are sensitive to over-and under-watering, preferring the soil to always stay moist but not sodden in all seasons except in winter. Only water them when the soil surface becomes dry.

During hot weather, these plants need regular watering twice weekly or even once every day, and never use cold water as cold water can shock the roots, damage the plants, and stunt growth. Over-watering and poor drainage will make the plants wither and rot. 


Boston Fern Humidity

Like most tropical plants, these ferns also require high humidity levels to survive and thrive, although they can tolerate average levels of humidity. However, low humidity might make the plants wither and die. Keep the plants away from drafts as dry air might cause damage.

They can thrive in bathrooms provided they have sufficient light. Misting can also help increase humidity levels. 


Boston Fern Temperature

These plants love warm or average temperatures of 60-80°F during the day with a minimum of not less than 50°F. If you can maintain this, their foliage will thrive and stay healthy.


Boston Fern Soil

These plants need soils that are rich in various nutrients and thrive in organic and porous soil. You can amend the soil with compost, pine bark, moss, or perlite.

This can help to improve the water retention of the soil along with keeping the soil well-drained. Most varieties of this species prefer acidic soils, although some grow in alkaline soils.


Boston Fern Repotting

Since these ferns are largely grown as indoor plants and as such need repotting when they become too big for their containers and their roots have filled their existing containers.

Boston Fern repotting

When repotting, ensure to maintain the same soil level they were first planted at and never bury the crown as this will cause crown rotting. 


Boston Fern Propagation

These plants are usually propagated by dividing the roots into quarters and planting them in new pots to get several new plants. This process can be easily accomplished.

First, remove the fern from the container – some effort might be needed as the roots can get attached to the container, don’t worry about exerting pressure as these plants can handle some harsh treatment.

Spreading out the roots before cutting the root ball will help make sure that every quarter has adequate roots and healthy leaves. Mist the roots of every new quarter properly before potting them into their new homes.

Use aerated, loose, and rich potting soil, making sure it is uniformly moist and crumbles at the touch. Water each new plant thoroughly after potting them, making sure excess water drains out.

Additional Care

These plants require all-purpose but light fertilizer with the right balance of potassium, nitrogen, and phosphorus with equal ratios of 20-20-20 or 10-10-10.

The fertilizer should be in liquid form and water-soluble or you can also use slow-release granules. However, based on some research conducted by several cultivators, water-soluble fertilizers are preferred as they can be diluted easily to reduce the risk of fertilizer burn.

Boston Fern Common Problems

Discolored leaves might be either due to wrong watering or over-exposure to harsh sunlight. It could also be due to pest infestations and over-fertilizing. Identify the exact cause for leaf discoloration and immediately take corrective measures.

Quite frequently, the fronds of these plants turn gray despite regular and correct watering. The culprit might be Pythium root rot causing such discoloration and it might lead to stunted fronds or the fronds withering away and dying.

Inspect the roots to see if they are stunted and/or brown – if either of these two indicators is present, you can be reasonably certain that the plants are suffering from root rot. 

This issue resolves to be proactive instead of being reactive. One option is to buy ferns that are healthy and disease-free. The other option is to ensure the soil is pathogen-free and fresh – a simple method to check this is to have a sniff of the soil as infected soil will smell bad.

You can also use suitable chemicals that might help address the issues instigated by Pythium root rot – if you do, make sure to also treat the soil, although the best choice is to replace the tainted soil with fresh soil and repot the ferns. 

Sometimes, the fronds of these plants might turn black and while this could be due to natural reasons, large-scale blackening or browning of fronds could suggest other problems. In most cases, the culprits might be nematodes hiding in the soil.

Add good quantities of compost into the soil to promote the growth of beneficial fungi that will help destroy the nematodes. However, if the infestation is severe, it would be best to remove badly infected plants to prevent this from spreading.

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