How to Take Care of Boston Ferns Outside

Boston ferns can live outside all year in USDA zones 9 to 11, and everywhere else they make great summer porch plants as long as you bring them in before nights drop below 50°F. Outdoors, a Boston fern wants shade or filtered light, soil that stays evenly moist, and shelter from wind and hot afternoon sun.

Get those basics right and a fern that looked tired on a windowsill fills out fast in summer air. Miss them and the fronds can crisp, yellow, or shed leaflets within a few hot, dry days.

Can Boston Ferns Live Outside?

Yes, and how long they can stay depends on your winter low. Gardeners in the warmest parts of the country can keep them out year-round, while gardeners in colder zones treat them as summer guests in pots and baskets.

Where Can They Stay Outdoors Year-Round?

Growing Boston ferns outside year-round works in USDA zones 9 to 11. That covers South Florida, the Gulf Coast, south Texas, coastal Southern California, and Hawaii.

In zones 10 and 11, the fern stays green through winter with little fuss. In zone 9, a light frost can burn the fronds to the ground, but healthy roots usually push out new growth in spring.

A hard freeze is a different story. If the soil and crown freeze solid, the plant won’t come back.

How Should You Grow Them in Colder Zones?

In zones 8 and colder (the Midwest, Northeast, Pacific Northwest, and most of the Southeast and Southwest uplands), keep your fern in a pot or hanging basket. That lets you move it outside in late spring and back inside in fall.

You have two good choices each fall:

• Overwinter it indoors as a houseplant in bright, indirect light.
• Let it go dormant in a cool garage or basement that stays between about 45 and 55°F.

Some gardeners in cold zones buy a new basket each spring and compost the old one. That’s fine too, but a fern kept for several years gets fuller and bigger each season.

When Should You Move a Boston Fern Outside?

Move your fern out once nights stay above 50°F and all frost danger has passed, then give it a week or so to adjust.

In much of the US, that lands in mid-to-late May, and closer to early June in northern New England and the upper Midwest.

Wait for Consistently Mild Nights

Daytime warmth can fool you in spring. A 70°F afternoon can still drop to 42°F overnight, and that kind of chill stalls growth and can brown the fronds.

I’d wait until your forecast shows a full week of nights at 50°F or higher, with 55 to 60°F being even better. Boston ferns grow best between 60 and 75°F, so warmer nights mean faster new growth.

If you want a deeper look at temperature limits, my guide on how cold ferns can tolerate compares tropical ferns with hardy native types.

Acclimate the Fronds to Outdoor Conditions

An indoor fern has soft fronds that aren’t used to wind, brighter light, or swings in temperature. Moving it straight into the yard can cause leaf drop.

Here’s the routine I recommend:

1. Days 1 to 3: Set the fern in full shade for 2 to 3 hours, then bring it back in.
2. Days 4 to 6: Leave it out most of the day in a sheltered, shady spot.
3. Days 7 to 10: Leave it out overnight if nights stay above 50°F, and move it to its summer spot.

Check the soil daily during this week. Outdoor air dries pots much faster than indoor air.

Where Should You Place It for the Right Light?

The best outdoor spot gives your fern shade or filtered light, with no direct midday or afternoon sun. A north- or east-facing porch, a covered patio, or the shade under a tree all work well.

Choose Shade or Filtered Light

Boston ferns grow on shady forest floors in the wild, so they like dappled light that moves through leaves. Filtered light under a high tree canopy, a lattice, or a deep porch roof copies that well.

A little gentle morning sun is fine in most of the country. Afternoon sun is the problem, especially in the Southeast and Southwest, where it’s hot and strong.

Good spots include:

• A covered front porch facing north or east
• Under a large shade tree, hanging from a low branch or set on a stand
• Beside a wall that blocks sun after noon
• Under a pergola with shade cloth

Watch for Scorching or Too Little Light

Your fern will tell you if the light is wrong. Too much sun shows up as pale, washed-out fronds, then crispy brown tips and patches.

Too little light looks different. You’ll see thin, stretched growth, a sparse center, and dull yellow-green color.

If you see scorch, move the plant a few feet deeper into shade right away. The burned fronds won’t turn green again, so trim them off at the base once new growth starts.

My article on ferns turning brown covers the other common causes of browning.

How Do You Water Outdoor Baskets and Pots?

Water whenever the top inch of soil feels dry, and keep the soil evenly moist without ever letting it stay soggy. For Boston ferns in containers outside, that often means daily watering in summer, and sometimes twice a day during heat waves.

Check the Soil Before You Water

Push your finger an inch into the soil. If it feels dry at that depth, water. If it still feels cool and damp, wait and check again later in the day.

You can also judge by weight. A dry hanging basket feels much lighter than one that was just watered, so lifting it gives you a quick read.

When you water, soak the pot until water runs out the drainage holes. A small splash only wets the top layer and leaves the roots dry underneath.

Outdoor condition	How often to check	Likely watering
Hot, dry, or windy (above 85°F)	Morning and late afternoon	Once or twice a day
Warm and humid (75 to 85°F)	Every morning	Daily or every other day
Mild or cloudy (60 to 75°F)	Every 1 to 2 days	Every 2 to 3 days
Rainy week	After each storm	Only if top inch dries

Keep Hanging Baskets Moist Without Waterlogging Them

Hanging baskets dry out the fastest because air reaches every side. Wire baskets with coir liners dry out fastest of all, while plastic baskets hold water longer.

A few habits help baskets stay evenly moist:

• Water in the morning so the fern starts the hot part of the day with full roots.
• Use a basket with drainage holes so extra water can leave.
• Empty saucers after watering so roots don’t sit in water.
• Group ferns together to raise the moisture in the air around them.

Yellow, droopy fronds and a sour smell from the soil mean the basket is staying too wet. Crispy, gray-green fronds mean it’s drying out between waterings. For more on schedules, see how often to water hanging plants.

How Much Fertilizer Do Outdoor Boston Ferns Need?

Boston ferns are light feeders, so a half-strength balanced liquid fertilizer about once a month from spring through summer is plenty. More than that does more harm than good.

Feed Lightly During Active Growth

Start feeding when you see new fronds unfurling in spring. Mix a balanced water-soluble fertilizer (such as a 20-20-20 or similar) at half the label rate.

Always water the fern first, then feed. Fertilizer on dry roots can burn them.

A slow-release fertilizer at half rate in spring works too, if you’d rather not mix liquid feed every month. Stop feeding by late August so the plant isn’t pushing soft new growth right before it comes inside.

I go over product types in my guide to the best fertilizer for ferns.

Recognize Signs of Overfeeding

Too much fertilizer burns frond tips first. You’ll see brown, dry edges even though the soil is moist.

Other signs include:

• A white, crusty layer on top of the soil or around the pot rim
• Wilting even when the soil is wet
• New fronds that come in small or twisted

If you see these, flush the pot. Run plain water through it slowly for a few minutes until it drains freely, then skip feeding for a month or two.

How Can You Protect Fronds from Wind, Heat, and Storms?

Keep your fern out of steady wind and hot afternoon sun, and move baskets to a sheltered spot before storms hit. Wind and heat dry fronds faster than anything else outdoors, and a heavy gust can strip a full basket.

Shelter Ferns from Drying Wind and Hot Sun

Wind pulls water out of fronds and soil at the same time. A fern in a breezy corner can need twice as much water as one tucked against a wall.

The best wind-sheltered spots are inside corners where two walls meet, porches with railings or screens, and spots behind shrubs or fences. Hang baskets low on a porch so the roof and walls block gusts.

Heat above 85 to 90°F stresses Boston ferns, even in shade. On those days, water in the morning, check again in the afternoon, and hose down the porch floor nearby to cool and humidify the air around the plants.

In dry Southwest heat, a light mist in the morning helps for a short while, though steady soil moisture does more.

Move Baskets to Safety During Severe Weather

Thunderstorms, hail, and hurricane winds can shred fronds and knock baskets off their hooks. When the forecast calls for severe weather, take baskets down and set them on the porch floor or in a garage.

Heavy rain can also overload pots. After a long soaking storm, tip saucers out and let the soil drain before you water again.

If an early cold snap is coming in spring or fall, bring the fern in for the night or cover it with a frost cloth. Pull the cover off in the morning so the plant doesn’t overheat.

Which Pests and Problems Should You Watch For?

Spider mites, mealybugs, and scale are the main insect pests on outdoor Boston ferns, and slugs show up often on ferns near the ground. Many problems that look like pests turn out to be watering or light issues, so a close look comes first.

Check Fronds for Spider Mites, Mealybugs, and Scale

Look at the undersides of fronds and along the stems once a week. Each pest has its own signs:

• Spider mites: Fine webbing, tiny moving specks, and dull, speckled, yellow-gray fronds. They thrive in hot, dry weather.
• Mealybugs: White, cottony clumps where leaflets meet the stem, plus sticky residue.
• Scale: Small brown or tan bumps that don’t move, often with sticky honeydew and black sooty mold.
• Slugs: Ragged holes in lower fronds and slime trails, with most damage overnight.

Start with the gentlest fix. A strong spray of water knocks off mites, and a cotton swab dipped in rubbing alcohol removes mealybugs and scale.

Ferns are sensitive to oils and soaps, so test any spray on one frond and wait two days before treating the whole plant.

For slugs, pick them off in the evening and set out slug traps or iron phosphate slug bait (used per the label) around in-ground plants. My guide to spider mites on indoor plants has more control steps that work on porch ferns too.

Tell Pest Damage from Watering Problems

Before you treat for bugs, rule out care problems. Here’s how the common symptoms line up:

What you see	Most likely cause
Crispy brown tips	Dry soil, dry air, wind, or overfeeding
Yellow fronds, soggy soil	Overwatering or poor drainage
Pale or light green fronds	Too much sun or not enough nitrogen
Leaflets shedding	Dry soil, drafts, or a recent move
Speckled fronds with webbing	Spider mites
Sticky fronds	Mealybugs or scale

If there’s no webbing, no white fluff, and no sticky residue, check your watering and light first.

How Do You Plant Them in the Ground in Warm Zones?

In zones 9 to 11, plant Boston ferns in a shady bed with rich, loose soil that drains well. Spring is the best time, so roots settle in before summer heat.

Prepare a Rich, Well-Draining Shady Bed

Pick a spot with shade from noon on, such as under trees or along the north side of the house. Turn the soil and mix in 2 to 3 inches of compost, leaf mold, or finely chopped bark.

Set the fern at the same depth it sat in its pot, firm the soil gently, and water deeply. Spread 2 inches of mulch around it, keeping the mulch an inch away from the crown.

In zone 9, cut frost-damaged fronds back in late winter and add fresh mulch over the roots. Boston ferns spread by runners in the ground, so give them room or edge the bed if you want to keep them in place.

Pair Ferns with Other Shade-Loving Plants

Boston ferns look great next to plants with broad or colorful leaves. Caladiums are a top pick in warm zones, since their bright pink, red, and white leaves stand out against fine fern fronds.

Hostas also work where they grow well, mostly in the cooler edges of zone 9. Other good partners include impatiens, coleus, begonias, and peace lilies in frost-free areas.

Choose companions that like the same steady moisture. Drought-loving plants and Boston ferns won’t both be happy in one bed.

When and How Should You Bring Them Back Inside?

Bring your fern in when nights start dropping toward 50°F, which falls in September for much of the North and October or later farther south. Clean it and check it for pests first so you don’t carry bugs inside.

Bring Pots In Before Nights Fall Below 50°F

Watch your forecast starting in late August. Once nights dip into the low 50s, start the move indoors, and have it done before nights hit the 40s.

Reverse the spring routine. Move the fern into deeper shade and closer to the house for a week, then bring it in. A sudden move from a humid porch into a dry heated house is the top reason for leaf drop in fall.

If you’d like a regional calendar, my guide on when to bring ferns inside lays out timing by area.

Inspect, Clean, and Isolate Ferns Before Rejoining Houseplants

Follow these steps before the fern comes indoors:

1. Trim yellow, brown, or straggly fronds at the base. Remove no more than a third of the plant.
2. Hose it off with a gentle spray, including the undersides of fronds.
3. Check for webbing, white fluff, brown bumps, and slugs under the pot.
4. Wipe the outside and bottom of the pot.
5. Isolate the fern in a separate room for 2 to 3 weeks before placing it near other plants.

If you have pets, see my post on Boston ferns and pets.

How Do You Care for a Boston Fern Through Winter?

Give your fern bright, indirect light, humid air, and cooler temperatures between 60 and 75°F. Water less than you did in summer and skip fertilizer until spring.

Give Indoor Ferns Indirect Light and Humidity

Set the fern a few feet back from an east window or near a south or west window with a sheer curtain. Keep it away from heat vents, radiators, and cold drafts by doors.

Indoor winter air is dry, and Boston ferns want 50% humidity or more. A humidifier works best. Misting helps for only a short time, and pebble trays help a little.

Expect some leaflet drop during the first few weeks inside. As long as new fronds keep coming from the center, the plant is adjusting.

If your house runs hot and dry, the dormant method is a fine choice. Keep the fern in a cool, dim garage or basement that stays between about 45 and 55°F and water it once or twice a month.

Reduce Watering and Stop Fertilizing Until Spring

Growth slows in winter, so roots use less water. Check the top inch of soil and water only when it feels dry, which may be once a week instead of daily.

Soggy soil in a cool room leads to root rot fast. Empty saucers after watering, and use room-temperature water.

Hold all fertilizer from fall until you see fresh fronds in spring. Then start half-strength feeding again and get ready to move the fern back outside once nights stay above 50°F.

Frequently Asked Questions