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. If you are stocking up, a balanced liquid fertilizer is the first thing I would pick up.
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:
- Days 1 to 3: Set the fern in full shade for 2 to 3 hours, then bring it back in.
- Days 4 to 6: Leave it out most of the day in a sheltered, shady spot.
- 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 w