So, you want to grow some Brussels sprouts over the winter.
Did you know that brassica oleracea can withstand even freezing temperatures for short periods? And that they love the cold?
In fact, it makes them taste even sweeter as they turn the plant starch into sugars!
But some people who live in colder areas (I’m looking at you, zones 4-7) need to do some TLC to keep them warm and grow them over the winter.
Others (zone 8) don’t need to do anything and can enjoy them all winter long.
Regardless, let’s dive in and see how to care for Brussels during the cold season.
How to care for Brussel sprouts over winter
Good news: Brussel sprouts are naturally a cold climate vegetable!
They’re well adapted for growing and producing over the winter as they are in the summer, spring, or fall.
Most people won’t have to change their gardening habits or strategies at all to keep Brussel sprouts healthy throughout the winter.
Brassica oleracea can tolerate cold chill down to 20F for short periods of time, but they generally do best in temperatures ranging between 40-70F for optimal production.
Similar to collard greens, they produce a tastier and sweeter crop when they’re exposed to some degree of cold.
Yup, that’s right.
The cold is good for them, but only when it’s not cold enough to kill them- as obvious as that sounds.
Exposing your Brussels to some cold will help make it tender to chew on and provide you with a sweeter taste rather than the bitter one.
If your sprouts always taste bitter, perhaps you haven’t been giving them enough time in the cold?
Or maybe your hardiness zone just doesn’t get cold enough for the best flavor.
When winter rolls around, the plant will destroy the starch in the plant leaves which turn into sugar.
This is why Brussels that have been through a few light chills taste much juicier with sweet flavor rather than that ugly bitter one.
I know. Some people can’t produce the temperature dips low enough o get that flavor.
Others are freaking out because their temperature is too low and the frost will kill their Brussel sprouts. The rest are somewhere in the middle.
Depending on your hardiness zone, the optimal flavor and production varies.
Do I need to do anything to protect Brussels over the winter?
This hardy cabbage does fine in the northwestern region of the US and people in these regions don’t need to do much of anything different compared to the summer.
If you’re growing them in zone 8 or higher, there’s not much you need to change for winter vs. summer growing.
Very little effort is needed in areas with the temperature above freezing. Even just tossing some mulch around the plant can be enough.
However, if you’re in a region such as zones 4-7, you’ll need to be careful. Brussel cabbage love the cold, but when it’s too cold, they can’t tolerate it.
That’s what this guide is for. You’ll find a variety of methods to keep them warm such as mulching, row covers, green-housing, and other means to keep your plant warm.
Brussel sprouts do best in USDA hardiness zones 3-9 with some going down to zone 2 and up to 10.
Some hardier variants are well suited for the colder regions and are bred to sustain extended frost at extreme temperatures.
But even then, you shouldn’t just leave them outside unprotected in the cold. If it’s too cold, protect them.
A cold snap is all it takes to kill them. And then you’ll end up with no harvest at all.
If you live in a warmer region with mild winters where the temp rarely dips below 40F, you’re set.
You don’t need to do anything special to care for your Brussel sprouts over the winter.
They’ll just do fine in the cold. Enjoy your sweet-tasting, tender sprouts!
However, if you’re in a colder region where the temperatures may drop below 40F, you’ll have to do some extra work.
It’s not much, but it’ll help protect and shield your sprouts from the harshness of winter so you can enjoy your harvest.
And that’s why you’re here. So let’s get on it.
Protecting your Brussel sprouts from the winter cold
Here are some tips to optimize your yield and keep your sprouts healthy and warm over the cold harshness of winter.
Most care remains the same, but you’ll make some adjustments to keep them protected.
Choose the right spot to plant
The location is everything.
You can create a nice microclimate to keep your Brussels safe and warm even if the outside temperature is very cold.
This works best for zones that are cold down to the mid-30s, but not extremely cold.
How it works is you choose a place in your garden that’s slightly warmer and shielded than other areas.
Believe it or not, your garden is not the same temperature all around. Usually, areas that are next to structures are a bit warmer than open areas.
Here are some places you can use to create microclimates:
- Next to your home’s exterior walls
- Fences or brick walls
- Plant edging
- Slabs of brick, concrete, or stucco
Pretty much anything that soaks up sunlight during the day and stores it well overnight into the cold.
This is basically an object that is resistant to quick temperature changes- it heats up slowly in the day and cools down slowly during the night. Just like a reptile.
This will heat your Brussel sprouts overnight during the winter. Protection is key.
If you’re growing Brussels in a container, it’s super easy- just move them.
But if you have them in the soil, you can consider transplanting them into containers for the winter only.
Avoid windy areas
The cold chill is worse than the actual cold temperature in my opinion.
The wind that carries the breeze makes it feel 10x colder than it really is. Avoid any windy or areas that have a draft, such as water or elevated areas that are exposed.
If you can’t, then consider getting something that blocks the wind like a small fence, edging, or just a piece of plywood.
Keep the soil dry
When the cold is here, the water leftover from your previous watering session will be extremely cold to the plant.
Water has a high specific heat, meaning it slowly warms up (or vice versa).
So when you water your Brussel sprouts in the daytime, the water soaked into the soil will sit there overnight.
The ambient temps drop and the water gets extremely cold and stays that way into the break of sunlight.
You’ll want to use well-draining soil, possibly with some kind of supplement added to improve drainage.
Consider adding mulch, perlite, or sand to keep the soil flowing so any excess moisture is released rather than stuck in the plant’s soil.
Plant-based on the last frost date
Similar to collard greens, you can maximize the flavor and texture of your Brussel sprouts by exposing them to a few light touches of frost before harvest.
The best way to do this is:
- Look at your seed packet and find out the days to harvest
- Find out your last frost date
- Plant the seeds so they can be harvested before the last frost, with a few weeks to spare
This will allow the crop to get some chill time hours and be harvested before the last frost approaches, which results in you getting your tasty sprouts and it not dying to the winter frost. Perfect.
This hardy cabbage does best in the cooler temperatures, so planting them at the right time is everything.
Typically, you’ll plant them in the late fall for a winter harvest.
The average Brussel sprout takes about 90-110 days to harvest. So if your last frost date was somewhere in late December, you’ll want to plant in early September.
But don’t rely on averages. Each hardiness zone has a different date for the very last frost of the season.
The time it takes to harvest also varies.
Start sowing seeds about 16 weeks before the last frost date in your hardiness zone. You can transplant them to your yard about 12 weeks before the last frost in the springtime.
Space them about 18” apart in rows that are 3 feet apart. Plant in full sun using a sheltered area from high winds (microclimate) if possible.
Brussel sprouts enjoy well-draining soil with a pH of 5.5 to 6.8 that’s rich in calcium and organic matter.
If you want to eat them over the winter, plant in early fall to late winter. They should be ready by spring.
If you want to eat them in the autumn, plant them in late May for a late fall harvest.
It really is all about timing. Sowing indoors increases the overall success rate rather than starting outdoors.
Use the power of the internet to find out the details you need to know.
Simply putting a plot of organic quality mulch around your plant soil will help keep it insulated.
It blocks out the cold from entering the soil and shields the root system from damage. It also prevents the soil from effectively freezing over a cold night. You can use straw mulch, pine needs, bark, leaves, or corn cobs that have been chopped.
Even regular leaves will help, but make sure they’re free of rot and fungus.
Use 3-4” of mulch around each Brussel sprout stem in a 12” radius from all sides of the plant. If you grow a bunch of them together, then just cover the entire plant bed at once.
Avoid touching the stem of the plant with the mixture when possible.
Use row covers
Row covers are an excellent way to cover your plants and help raise the temperatures or keep them stable. Use floating row covers and secure it at the soil’s surface.
Keep as much of the cover grounded as you possibly can by sealing up all crevices. This will keep all cold air out and trap the warm area inside it.
You can also use some stakes as supports to help keep the row covers erect.
A wire cage, sticks, or even wooden beams also work.
This will prevent any snowfall from coming down on your row covers and ruining your Brussel sprouts. Row covers can be used for chilly periods that last a long time rather than a single cold snap.
You need to watch the weather and act accordingly. If you’re expecting snow, install a row cover system on your Brussel sprouts to protect them.
Combine the row covers, mulch, and microclimate for a powerful combo against the frost of winter.
Consider a greenhouse
A greenhouse would be the top choice for those who can afford it and have space for it. It’ll provide your Brussels sprouts with a temperature-controlled environment- perfect for stabilizing the temperature throughout the winter.
Some greenhouses also have some built-in heaters, which can activate when the ambient air drops to a certain point. Or you can use the old fashioned one with window slits that are manually controlled by you.
Allow air entry during the day for it to heat up and shut them at night to trap in the heat!
Don’t be afraid of checking some designs out. Some greenhouses are extremely small and space-saving for under $50 online.
Or build a cold frame storage
If you’re handy, a cold frame storage solution may be your next project.
Cold frames are small wooden rectangles or squares that provide coverage for flower beds and can be made for cheap (like $20 cheap).
You just need a few pieces of plywood and some kind of protective cover for it to keep the cold out and warm air inside.
There are tons of blueprints online you can find for free.
Or just watch a video and follow the steps. Even if you’re not handy, you can still put something together, right?
Anything you can slap together should provide some degree of protection. Looks don’t matter.
Practice crop rotation
Be sure to rotate your Brussels spouts with other plants regularly.
This will reduce the overall chance of plant disease. Avoid planting another cabbage plant in the same family to stop the spread of infection.
If possible, plant something else entirely in the same plot that’s not even a vegetable.
You can move the Brussels back into the same location after 3 years or so. This will ensure that most of the harmful pathogens are gone and greatly reduce the chance of plant infection.
Brussel sprouts appreciate plant food at least 2-3 times during their growth.
They’re cold hardiness require some feeding to keep them stable during the winter.
Fertilize with high phosphorous plant food that’s rich in nitrogen such as blood meal or fish emulsion when you first plant them. Fertilize again a few weeks later after they establish themselves.
Your soil should be slightly acidic with well-draining soil. You can add some calcium supplement as well if needed.
Brussel sprouts are top-heavy plants, so they appreciate plant stakes or some other plant support to help them stand up.
Best types of Brussel varieties for winter growing
Some cultivars of Brussel sprouts do well in the cold compared to others.
Look for these following these for early winter harvest:
- Prince Marvel
- Jade Cross
These are good choices for those in a cold hardiness zone with harsh winters. You’ll want to harvest before it’s too cold and these varieties will be ready earlier.
If you’re in a zone with a mild winter (zone 8 or higher), you can get a late bloomer which will grow through the winter for that sweet taste and soft texture:
If you’re trying to grow them somewhere that’s extremely cold for extended periods, consider uprooting them for wintertime storage.
For those that live somewhere with temps as low as 10F, you’ll need to either protect them with an outdoor greenhouse or cold frame or extract them to be taken indoors.
They can be pulled by carefully digging the plant out and then stashing the plant into a container with sand. You can damp the sand slightly.
Store the container somewhere that’s dry to avoid excess moisture. This is only necessary if the cold winter in your area is unbearable.
Do this in the fall before the winter. Keep the roots covered by the sand and replant in the spring after the last frost.
Will a freeze damage Brussel sprouts?
Remember that these crops are cold-loving so they do fine even in freezing temps.
But only for a short period. If a single cold snap happened last night or a winter freeze lasting a few days occurs, you don’t need to be worried as long as the dips aren’t crazy low (10-20F).
It’s unlikely that an overnight chill will do any serious damage to your Brussels sprouts as they can tolerate short periods of cold.
But if the snap lasts more than a few days, you’ll have to do something about it to keep your plants warm.
Here are some additional references you may find helpful:
- Brussels sprouts – Wikipedia
- Growing Brussels sprouts in home gardens – UMN Extension
- I can plant seeds in the winter?!?! : gardening – Reddit
Are you going to grow Brussels all winter?
These delicious and nutritious veggies are made for the cold.
You should have a basic understanding now of how to care for, grow, and protect your Brussel sports over winter.
A cold-hardy plant that only gets sweeter with the dropping temperatures.
Perfect for beginners and easy enough to grow all season.
Plus, it beats paying for Brussels at the supermarket when you have your own, juicy, and organic sprouts all around.
These crops are only becoming more popular over time and food good reason. Their nutrition profile is top notch and they’re becoming sweeter and tastier as we home gardeners develop our techniques!
What do you think? Will you be eating sprouts all winter long? Do you have any tips to give other readers? Do you have any questions about raising this crop?
Just post a comment below and let us know!
I took interest into microflora and microgreens before it became mainstream. The idea of growing an entire ecosystem on a tiny scale simply was astounding. That’s where I discovered that I actually like raising plants and wasn’t as much of a black thumb as I thought. Now, I’m relaying what I’ve learned to others who are getting into the hobby in a way that anyone can understand.