6 Easy Steps To Winterizing Fern Plants: Complete Step-By-Step Guide

I killed three Boston ferns my first winter as a plant owner. Left them on my covered porch thinking “covered” meant “protected.” Came outside in March to brown, crispy, completely dead plants. Each fern had cost me $24. That’s $72 wasted because I didn’t know ferns can’t handle cold.

Last fall, I actually researched how to winterize ferns before the first frost. Followed six simple steps. All eight of my ferns not only survived winter but came back fuller and healthier than before. Some even produced baby ferns in spring.

Here’s what actually works for keeping ferns alive through winter. This applies whether you have Boston ferns, maidenhair ferns, bird’s nest ferns, or any other popular variety. The process takes about 30 minutes per plant and costs almost nothing if you already have basic supplies.

Understanding Why Ferns Die In Winter

Most popular ferns are tropical or subtropical plants. They evolved in warm, humid environments without freezing temperatures. Boston ferns are native to tropical regions worldwide. Maidenhair ferns come from humid forests. These plants have zero cold tolerance.

Frost kills fern fronds immediately. The water inside plant cells freezes and expands. This ruptures cell walls. The damage is permanent. You can’t revive frozen fronds. They turn brown and die.

Even temperatures above freezing but below 50 degrees stress most ferns. Growth stops. Fronds turn yellow. The plant goes dormant or declines. Extended exposure to cold damages roots even if fronds survive initially.

My covered porch got down to 28 degrees several nights that first winter. The roof kept snow off but didn’t prevent freezing air. My ferns never had a chance.

Different fern varieties have different cold tolerance. Hardy outdoor ferns like autumn ferns and Japanese painted ferns survive freezing and come back from roots in spring. But the popular hanging basket ferns sold at garden centers are tropical. They need protection.

Know Your First Frost Date

Everything depends on timing. You need to winterize before the first frost. After frost damage occurs, you’re too late.

Google “first frost date” plus your zip code. Various sites provide average first frost dates for your area. In my Zone 6b location (southern Pennsylvania), average first frost is October 15. I winterize by October 1 to be safe.

First frost dates are averages. Some years, frost comes two weeks early. I learned this the hard way Year One. Waited until mid-October. Frost hit October 8. Three dead ferns.

Set a calendar reminder for two weeks before your average first frost date. That’s your winterizing deadline. Earlier is better than later. Moving plants inside when it’s still 60 degrees at night won’t hurt them. Waiting too long kills them.

Watch local weather forecasts starting in late September. If a frost warning appears, move plants immediately regardless of your planned timeline.

Step 1: Decide Which Ferns To Save (Be Honest)

Not all ferns are worth the effort to overwinter. Some are in rough shape. Some are too large to manage indoors. Some you’re honestly tired of.

I had ten ferns going into my second fall. Two were straggly and sparse from pest damage over summer. One was absolutely massive (4 feet across) and would take up half my living room. I composted those three and focused on the healthy, manageable ones.

Here’s my decision criteria:

Save these ferns:

• Healthy plants with good color and full foliage
• Plants you genuinely love and want back next year
• Manageable sizes that fit your indoor space
• Varieties that are expensive to replace ($20+ plants)

Let these ferns go:

• Plants with significant pest damage or disease
• Plants that struggled all summer despite good care
• Enormous plants that won’t fit anywhere inside
• Cheap varieties you can replace for $10 in spring

Boston ferns cost $24-30 at garden centers. Worth overwintering. The $8 discount store ferns that barely grew all summer? Not worth the hassle. Compost them guilt-free.

Be realistic about space. One large fern indoors takes up the room of five small houseplants. If you don’t have space, don’t try to cram ten ferns into a tiny apartment. Save your favorites and let the rest go.

Step 2: Inspect And Clean Your Ferns (15 Minutes Per Plant)

Before bringing ferns inside, deal with any pest or disease issues. You don’t want to introduce problems to your other houseplants.

Check the entire plant carefully. Look under fronds. Check where stems meet the soil. Inspect the pot exterior and drainage holes.

Common pests on outdoor ferns:

• Spider mites (tiny dots, webbing between fronds)
• Scale insects (brown bumps on stems)
• Aphids (small green or black bugs on new growth)
• Fungus gnats (tiny flies around soil)

I found spider mites on two of my ferns last fall. Caught them early during inspection. Sprayed the plants with insecticidal soap (bought at Lowe’s for $9). Let them sit outside for three more days. Sprayed again. Brought them in only after confirming mites were gone.

Remove any dead or damaged fronds. Cut them at the base with clean scissors. This improves appearance and removes potential disease sources.

Wipe down the pot exterior with a damp cloth. Remove dirt, cobwebs, and any bugs hiding on the pot. Clean the saucer or drip tray too.

Check the soil surface for weeds. Pull any weeds growing in the pot. Outdoor pots often accumulate weed seeds over summer. You don’t want weeds sprouting indoors.

This inspection and cleaning process takes about 15 minutes per plant. Seems tedious but it’s worth it. One infested plant brought inside can spread pests to your entire houseplant collection. Ask me how I know.

Step 3: Trim Back Leggy Or Damaged Growth (10 Minutes Per Plant)

Ferns get ratty looking by fall. Long summer growing seasons create leggy fronds that drag on the ground. Stems get damaged by wind or rain. The plant looks messy.

I trim my ferns before bringing them inside. This makes them more compact and encourages fresh growth indoors.

Use clean, sharp scissors or pruning shears. Cut damaged or excessively long fronds back to the base of the plant. Don’t be shy about removing up to one-third of the total fronds.

For Boston ferns and similar varieties, I typically remove the outermost ring of fronds that hang down past the pot. These are usually the oldest, most damaged fronds anyway. The plant looks instantly neater.

Don’t scalp the plant. Leave a good amount of healthy growth. The fern needs foliage to photosynthesize and maintain itself through winter.

Some people recommend cutting ferns back severely before overwintering. I tried this approach and had mixed results. Some ferns bounced back great in spring. Others struggled and took months to fill back out. Now I remove about 20-30 percent of fronds. That balances neatness with keeping enough plant mass for healthy indoor survival.

After trimming, the pot is lighter and easier to move. The plant looks groomed and attractive. It takes up less space indoors.

Step 4: Move Ferns To Appropriate Indoor Location (The Most Important Step)

Location determines success or failure with overwintering ferns. Get this wrong and your ferns decline no matter what else you do right.

Ferns need three things indoors: moderate light, high humidity, and temperatures between 60-75 degrees.

Light requirements:

Ferns prefer bright indirect light. A north or east-facing window is ideal. They can handle a few hours of gentle morning sun but not harsh afternoon sun through west or south windows.

I keep mine in my bathroom with a north-facing window and in my living room about 6 feet from an east window. Both locations provide enough light without being too intense.

Low light locations like interior rooms with no windows don’t work. The ferns will gradually decline and lose fronds. They need to photosynthesize to stay healthy.

Humidity requirements:

This is where most people fail with indoor ferns. Our houses are dry in winter. Heating systems remove moisture from air. Ferns hate dry air. Their fronds turn brown and crispy at the tips when humidity is too low.

Solutions that actually work:

Group ferns together: Plants release moisture through transpiration. Grouping them creates a more humid microclimate. I have five ferns clustered on a plant stand in my bathroom.

Use a bathroom location: Showers and baths add humidity to bathroom air. My bathroom ferns look way better than the ones in drier rooms.

Add a humidifier: I bought a small cool-mist humidifier on Amazon for $28. Run it near my ferns in the living room. Makes a noticeable difference in frond health.

Pebble trays: Put a layer of pebbles in a wide tray. Add water to just below the top of the pebbles. Set the fern pot on top of the pebbles. As water evaporates, it increases humidity around the plant. This works but requires refilling water frequently.

What doesn’t work: Misting. People love to recommend misting ferns daily. I did this religiously for a month. Made zero difference. Misting provides humidity for maybe 10 minutes. Then it evaporates. Not worth the daily effort.

Temperature requirements:

Keep ferns away from heating vents, radiators, fireplaces, and drafty windows. Temperature extremes and hot dry air kill ferns faster than anything except frost.

My living room stays 68-70 degrees all winter. Perfect for ferns. My bedroom gets down to 62 at night (I prefer sleeping cold). Also fine. Anywhere in the 60-75 range works.

Step 5: Adjust Your Watering Schedule (This Changes Everything)

Outdoor ferns need frequent watering. Summer heat and air circulation dry them out quickly. Indoor ferns in winter need way less water.

This is where people overwater and kill their ferns. They continue the summer watering schedule indoors. The soil stays constantly wet. Roots rot. The plant dies.

Indoor ferns in winter are semi-dormant. They’re not actively growing much. They’re just maintaining themselves. Water needs drop dramatically.

Here’s my indoor fern watering schedule:

Check soil moisture every 5-7 days. Stick your finger 2 inches into the soil. If it feels dry at that depth, water thoroughly. If it still feels moist, wait another few days.

Water thoroughly but infrequently. When you water, soak the soil completely until water drains from the bottom. Then let it dry out partially before watering again.

Never let ferns sit in water. Empty the drip tray or saucer 30 minutes after watering. Soggy soil kills ferns.

I water my indoor ferns about once per week in winter. Sometimes it stretches to 10 days. That’s normal. Resist the urge to water more frequently just because you’re used to summer’s schedule.

The one exception is if your humidity is really low. Dry air can dry out soil faster. But even then, check before watering rather than following a rigid schedule.

Step 6: Skip Fertilizer Until Spring (Seriously, Skip It)

Ferns don’t need fertilizer during winter dormancy. They’re not actively growing. Feeding them pushes weak growth that struggles in low winter light.

I made this mistake Year Two. Thought I was being helpful by giving my ferns a dose of liquid fertilizer in January. They responded with pale, weak fronds that looked sickly. Learned my lesson.

Stop fertilizing in September when you bring ferns inside. Resume in April when you move them back outside or when you see vigorous new growth starting.

When you do fertilize, use half-strength liquid fertilizer designed for houseplants. I use Miracle-Gro Indoor Plant Food diluted to half the recommended strength. Feed monthly during the growing season.

What To Expect During Winter

Your ferns will not look as lush and perfect as they did outdoors in summer. That’s normal. They’ll lose some fronds. New growth will be slower and less vigorous. Some fronds might brown at the tips despite your best efforts.

This is fine. The goal is survival, not perfection. A somewhat sad-looking fern in March that’s still alive will explode with growth once you move it back outside in spring.

I typically lose about 20-30 percent of fronds over winter. The plants look a bit thin by March. But within three weeks of moving them back outside in April, they’ve already grown noticeably. By June, they look better than the previous year.

Don’t panic if a few fronds turn brown or yellow. Remove them and carry on. Panic only if you’re losing massive amounts of fronds rapidly (more than half the plant). That indicates a watering issue or pest problem that needs immediate correction.

Transitioning Back Outside In Spring

Don’t rush this step. Wait until nighttime temperatures stay consistently above 50 degrees. In my area, that’s usually late April.

When you move ferns back outside, do it gradually. Put them in a shaded location for a week. This lets them adjust to outdoor conditions without shock. Then move them to their final location with appropriate light.

Water more frequently as temperatures warm and growth resumes. Start fertilizing monthly. Within a few weeks, your ferns will look like their outdoor summer selves again.

Alternative: Garage Or Basement Overwintering

If you don’t have good indoor space, you can overwinter ferns in an unheated garage or basement. This works only if temperatures stay above 40 degrees.

The plants will go fully dormant. They’ll lose most or all fronds. Water very sparingly (once per month) to keep roots from drying out completely.

I tried this method with two ferns as an experiment. Both survived but took until July to recover and fill out. The ferns I kept actively growing indoors looked great by May.

Garage overwintering is better than losing plants entirely. But if you have indoor space, that’s the better option for faster recovery.

Frequently Asked Questions

Can I leave ferns outside if I cover them?

Not for tropical ferns like Boston ferns. Covering protects from frost but doesn’t prevent freezing temperatures from killing the plant. Hardy outdoor fern varieties can overwinter outside with mulch protection, but hanging basket varieties need to come inside.

How much light do indoor ferns need?

Bright indirect light. A north or east-facing window is ideal. They can tolerate lower light but will decline over time. Avoid direct afternoon sun through south or west windows.

Why are my fern fronds turning brown indoors?

Usually low humidity. Increase humidity with a humidifier, pebble tray, or bathroom location. Brown tips can also indicate underwatering or salt buildup from fertilizer.

Can I keep ferns in my bedroom?

Yes, if the room has adequate light and stays between 60-75 degrees. Bedrooms tend to be drier, so you may need a small humidifier for best results.

Do I need to repot before bringing ferns inside?

Only if the fern is severely rootbound. Otherwise, wait until spring to repot. Fall is not ideal timing for repotting since plants are entering dormancy.

How do I know if my fern has spider mites?

Look for tiny webbing between fronds, stippled or pale fronds, and tiny moving dots on leaves. Hold a white paper under the plant and shake it gently. Mites will fall onto the paper and be visible.

Can I propagate ferns in winter?

You can, but success rates are lower. Better to wait until spring when plants are actively growing. Boston ferns produce runners with baby plants that root easily in spring.

What if I don’t have space for all my ferns?

Save your favorites and healthiest plants. Let the rest go. You can buy new ferns in spring for $10-30. Not every plant is worth the indoor space commitment.

Why is my fern losing fronds?

Some frond loss is normal during winter dormancy. Excessive loss indicates overwatering, underwatering, too much direct sun, or pests. Check soil moisture and inspect for bugs.

Can I cut my fern all the way back before bringing it inside?

You can, but I don’t recommend it. Removing all fronds is harsh and makes recovery slower. Remove damaged fronds and trim for neatness, but leave at least 70 percent of healthy growth.

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Winterizing ferns isn’t complicated. The six steps above take about an hour total per plant. That’s a small time investment to save plants that cost $20-30 each.

The difference between dead brown ferns in spring and lush green plants ready to hang back outside is knowing what ferns need and providing it before winter arrives.

Pick one fern to start with this weekend. Follow these six steps. See how well it does over winter. Next year, you’ll know exactly what works and you’ll confidently overwinter every fern you own.

Which step are you starting with today? The inspection and cleaning step is perfect for a Saturday afternoon. Your ferns will thank you all winter long.