How to Grow and Care for Boston Fern

Boston fern, also known as sword fern, is a popular fern species that grows in many tropical areas around the world. In North America, it is considered a classic houseplant and is easy to care for, as it doesn’t require a lot of sunlight and can live on for years. It also purifies the air and increases humidity in a room. Outdoors, this perennial plant thrives in swampy, humid, and forested areas, and makes a good choice for partial-shade gardens in places like Southern California or Florida.

Its sword-shaped, blue-green foliage contains tiny leaflets and grows erect, arching only when fronds grow larger, which can reach 4 feet long and 6 inches wide. Like several other fern species, Boston fern grows quickly when young and becomes more of a slow-grower as it matures. It is best planted outdoors in the fall or spring or indoors year-round.

Boston Fern Care

Here are the main care requirements for growing a Boston fern.

• This plant prefers warm and humid conditions. Mist to raise the ambient humidity.
• Give Boston fern a spot in filtered bright light.
• Opt for loamy soil with good drainage.
• Water Boston fern frequently to prevent the soil from drying out and fertilize the plant regularly during its active growing stage.
• Provide an inch of compost and mulch annually.

Light

Boston fern grows best in bright, indirect light. Too much shade can result in sparse, lackluster fronds. Too much sun can burn the fronds. Boston fern thrives as a porch plant that receives filtered morning sun and afternoon shade.

Soil

Ferns prefer organically rich, loamy soil with good drainage. Add compost and peat to your outdoor garden before planting. For a potted Boston fern, use a peat-based potting mix with added perlite for increased drainage capacity.

Water

Keep the soil lightly moist during the spring and summer growing months with once-weekly watering for houseplants and more frequently for outdoor Boston ferns in warm climates. Water every other week during fall and winter dormancy. Fronds may droop in dry soil.

Temperature and Humidity

Boston fern prefers temperatures between 65 and 75°F. Temperatures above 95°F and below 35°F harm the plant. This fern thrives in humidity levels above 80% which can be achieved with misting or a pebble tray. Low humidity causes frond tips to turn brown. Indoors, keep the plant away from extreme temperatures and indoor drafts from air conditioners or heating vents.

Fertilizer

For outdoor Boston ferns, amend the soil with 1 inch of compost and mulch annually to maintain good growing conditions. Feed indoor ferns once a month during the spring and summer using a 20-10-20 liquid houseplant fertilizer at half strength. Do not fertilize in the late fall and winter months.

Types of Boston Fern

Boston fern comes in several varieties, including dwarfs. Here are a few popular options:

• Nephrolepis cordifolia 'Duffii': This dwarf Boston fern, also called lemon button fern, is the perfect size for indoors and gives off a lemony scent when its leaves are crushed. It is more resilient and less fussy than some other ferns.
• Nephrolepis exaltata 'Compacta': This short, compact, and upright version of the Boston fern species is considered sturdier than other varieties because it withstands a little heat and dryness.
• Nephrolepis exaltata 'Florida Ruffle': This medium-sized cultivar has feathery, ruffled fronds that grow in a dense clump. This plant can be grown both indoors and out but thrives in an ultra-humid environment.
• Nephrolepis exaltata 'Golden Boston': This fern yields golden leaves and can be grown outside in a pot, and then overwintered indoors to be relocated outside again the next season. This variety is considered low-maintenance.
• Nephrolepis exaltata 'Rita's Gold': Similar to 'Golden Boston,' this fern also grows yellow, almost chartreuse, fronds. It shimmers in the sunlight and compliments impatiens and begonias in a container setting.
• Nephrolepis exaltata 'Fluffy Duffy': This type of fern is small, dense, and finely textured. This variety's feathery fronds look great in hanging baskets, and it benefits from a daily misting year-round.

Pruning

Boston fern responds well to drastic pruning which encourages bushy growth and corrects legginess. The best time to prune an indoor plant is when it's repotted. Remove all browning leaves and clip back leafless runners. Give your fern a good haircut by trimming off the side fronds at the base with sharp shears. Leave the top of the plant unpruned, but rather trim around the edges to your desired shape.

Potting and Repotting

Boston fern prefers containers that take longer to dry out. like plastic or glazed terra-cotta pots with ample drainage holes. Repotting is best done in the spring, once you see roots poking out of the soil. Large Boston ferns can be divided into separate pots.

Select a pot size that is slightly larger than the plant's root ball, or size up your pot by 2 inches. Gently remove the fern from its old pot, and replant it at the same depth using a fresh potting mix. Take care to bury all the roots, and then give your fern a good drink of water. Place your pot in a warm area in your home, out of direct sunlight.

Propagating Boston Fern

Boston fern is very easy to propagate by division. This method is good to use for a fern that has outgrown its pot or is taking over a garden space. Take these steps in the spring.

1. Gather a sharp pair of garden shears, a garden trowel (for indoor plants), a spade shovel (for outdoor plants), a pot, and potting soil (for indoor plants only).
2. Carefully separate a section of your fern with healthy roots attached. Use a garden trowel to separate indoor plants, and a spade shovel to carefully pull apart outdoor plants. Smaller sections can be divided and established, as well.
3. Fill a pot halfway full with potting soil (for indoor plants) or dig a new hole in the garden (for outdoor plants).
4. Plant your division into either the mix or the ground, taking care to fully cover the roots when you backfill the hole with soil.
5. Water the new division, and keep the soil lightly moist at all times. Keep indoor plants in a warm spot away from drafts and temperature fluctuations, and out of direct sunlight.
6. After a few weeks, gently pull on the base of the fronds. If you feel resistance, you know your fern has taken root.

How to Grow Boston Fern From Spores

Like all ferns, Boston fern does not generate seeds. Instead, ferns are grown from spores collected from adult plants. You can also purchase fern spores from a garden store.

Here's how to grow Boston fern from spores:

1. Gather a sheet of paper, a jar, potting soil, and pots (for indoor plants), or compost and peat (for outdoor plants).
2. Hold your paper under the fronds of an adult fern and shake gently to help spores fall from the underside of the leaves.
3. Collect the spores in a jar and select a warm area for planting.
4. Prepare your pot with potting soil or prep an outdoor area with a mixture of compost and peat.
5. Wet the soil and broadcast the spores over the surface of the pot or the garden plot. Mist or gently water the soil to keep it moist at all times.
6. In about a week, check the pot or garden for a thin green haze (prothallia) that contains the sperm and the egg. Continue misting to hasten fertilization.
7. Mist frequently until you see the prothallia sprout, and then water the seedlings on a regular schedule to maintain moist soil conditions.

Overwintering

Cut your potted Boston fern back to 4 inches above the soil and store it in a cool, dry area, like a basement or garage. Water your fern once a month until spring, and then relocate it outside for a few hours each day, once outdoor temperatures warm up.

For garden ferns grown in zones 9 to 11, perform a late fall cutback and withhold fertilization. Spread a thin layer of compost and mulch at the base of the plant and water it throughout the winter, as needed, to keep the soil barely moist.

Common Pests & Plant Diseases

A Boston fern grown outside can become a target for whiteflies, mealybugs, snails, slugs, and caterpillars. Whiteflies and mealybugs suck the plant's juices and leave behind a sticky mold. Chewing insects leave a slimy trail and cause holes in the leaves. Control whiteflies and mealybugs with several blasts from the garden hose and handpick slugs, snails, and caterpillars off plants.

Indoor and outdoor ferns can also suffer from blight, a fungal infection that leaves the plant covered in a brown web-like mycelium. Treat by repotting the plant in a sterile container and discarding the diseased soil in the process. Only treat the fern with a fungicide when all other methods have failed.

Common Problems With Boston Fern

Overwatering your Boston fern can result in root rot, which causes your fern's fronds to turn gray and its roots to brown. Repotting and discarding the diseased soil is the best treatment for this problem. Root rot can also be prevented by providing ample drainage and airflow to the fern's roots.

From: thespruce