How to Overwinter Ferns
Every fall I get the same question: can my ferns make it through winter? The answer depends on which fern you have. Kimberly Queen, Boston and Macho ferns are tropical and are not cold hardy, so they need to come inside. Autumn ferns planted in the ground are true perennials and can stay right where they are all winter. Here is exactly how to overwinter your ferns so you can enjoy them for years to come!
Which ferns need to come inside for winter?
Kimberly Queen, Boston and Macho ferns need to come inside for winter because they are not cold hardy and will not survive a hard freeze. These are the ferns most of us buy in containers and hanging baskets every spring. They only stay outside year round in the warmest zones, 9 through 11.
Kimberly Queen is my favorite fern, and she is the one I tell clients to use in containers. Boston ferns are my pick for hanging baskets. Both are worth saving, because a fern you overwinter comes back bigger and fuller than anything you can buy in April.
Find out how to tell the difference between a Boston fern and a Kimberly Queen in this video.
Which ferns can stay outside all winter?
Autumn ferns planted in the ground can stay outside all winter because they are perennials that come back year after year. You do not need to dig them up, cover them or bring them in. Just leave the fronds on through winter, add a layer of mulch around the base, and trim off any ragged fronds in late winter before the new growth unfurls.
This is exactly why I reach for autumn ferns when I plant after spring. They last the whole season and then keep going for years. Holly ferns and Christmas ferns are two more in-ground ferns that handle winter outside in most Southern gardens.
A quick note on Macho ferns: they are big and beautiful in the ground, but outside of zones 9 through 11 they will not come back. Treat them like your Kimberly Queens and Bostons and bring them in.
When should you bring ferns inside for winter?
Bring your ferns inside before nighttime temperatures drop to 40 degrees. Do not wait for the first frost. By then the damage is already done. Watch your ten day forecast in the fall and move them in as soon as you see those 40 degree nights coming.
How do you get ferns ready to come inside?
Get ferns ready to come inside by hosing them off, soaking the pot, then spraying with neem oil, and cutting them back. This keeps you from bringing pests into the house along with your plants.
How to Bring Ferns Inside for Winter
Hose, soak, then neem. Give the whole fern a good hosing, soak the pot, then spray with neem oil. Neem takes care of any little hitchhikers hiding in those fronds.
Cut them back. Each fern gets a different haircut:
Boston ferns: cut back by 1/2
Kimberly Queen ferns: cut back by 1/3
Macho ferns: cut back by 2/3
I know it feels drastic, but cutting them back is what keeps them manageable indoors and sets them up for strong new growth in spring.
How much do you cut back ferns before winter?
You need to give your ferns a MAJOR haircut before bringing them inside.
Wondering how much you need to cut back on your fern fronds? It depends on the fern. As scary as it sounds… Cut them back by A LOT. I shear mine down to about 3-4” above the root, but if you’re concerned, you can shear your ferns using these guidelines-
Boston ferns: cut back by ½
Kimberly Queen ferns: cut back by 1/3
Macho ferns: cut back by 2/3
Do it right before they come in, ahead of those 40 degree nights. It feels drastic, but a good haircut keeps them manageable indoors and sets them up for big, full growth come spring.
There are a few reasons for this.
1. It helps the roots hunker down over winter and not expend energy out to the fronds
2. All those brown fallen frond leaves stay messy outside, not in my sunroom!
MY BEST FERN HAIRCUT ADVICE:
Use a pair of small hand-held electric grass shears to make it fast and easy. These grass clippers are affordable and work great for the home gardener.
I’ve got a demo of how I give my ferns a haircut on my Youtube channel. Make sure you’re following along over there for all the good gardening tips.
Where should you keep ferns over the winter?
Keep ferns in a spot that is either cool and dark or has bright, indirect light. A cool, dark garage or basement lets them go fully dormant. A room with bright, indirect light keeps them green and growing slowly. Both work. Just avoid a hot, dry spot right next to a heating vent.
SHOP FERN CARE FAVORITES
Find all my favorites for fern care, fertilizing, and overwintering here:
How often do you water ferns in winter?
Water ferns only about once a month while they are dormant. This is where most people lose their ferns. Ferns rot far faster than they dry out, so less is truly more in winter. Let the soil dry down between waterings and never let the pot sit in standing water.
When should you stop fertilizing ferns in the fall?
When you stop fertilizing ferns depends on your zone. As the weather cools, ferns slow down and do not need the food. I use Jack's liquid feed at 1/2 strength on my Kimberly Queen, Boston and Macho ferns, and here is my fall feeding schedule by zone:
When TO Stop fertilizing ferns by zone
Zones 3 to 7: Stop feeding on the first day of fall (September 22).
Zone 8: One last feed, done by October 1.
Zone 9: Feed every 2 to 3 weeks through October.
Zones 10 and 11: Keep feeding, and go to once a month as it cools.
When do you bring ferns out of dormancy?
Wake your ferns up in February by repotting them and starting a 1/2 strength feed. Fresh soil and a light feeding give them a head start, so by the time it is warm enough to move them back outside, they are already pushing out new fronds. By summertime, they will need lots of fertilizer!
Watch this video to see my four week fertilizer schedule once the warmer weather hits.
Should you use Epsom salt on ferns?
Yes, but SPARINGLY and not until Spring. Be sure to follow the fertilizer timeline above and dilute completely in a big pitcher of water so you don’t burn them.
Click here for my Secret Sauce to Happy Ferns and Flower recipe using Epsom salt.
Quick recap: how to overwinter ferns IN POTS
Move them in before nights drop to 40 degrees.
Spray with neem. Hose them off, soak the pot, then spray neem oil.
Cut them back. Boston by 1/2, Kimberly Queen by 1/3, Macho by 2/3.
Pick a spot that is cool and dark, or has bright indirect light.
Water monthly in dormancy. They rot far faster than they dry out.
Wake them in February. Repot, then start a 1/2 strength feed.
And if your autumn ferns are planted safely in the ground, you are off the hook. They will be fine without coming indoors. Let them be, and they will greet you again in spring.
Looking for More Fern Care Advice? LEARN MORE:
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