Brussel sprouts may get a bad rap among kids but they can be one of the most exciting, hardy, and delicious vegetables to grow in the garden. But, what does it mean when the plants don’t form the classic sprouts we all know and love?
The main reasons Brussel sprouts don’t form heads are due to nitrogen deficiencies in the soil, too warm of a climate, or plants needing to be topped off. Any combination of these things is likely to leave you with little to no Brussel sprouts.
Luckily, there are some things you can do to remedy these situations and ensure that you have plenty of sprouts to harvest this season. Read on to learn more about Brussel sprout growth and what varieties are the best at forming heads.
How long do Brussel sprouts take to form?
Brussel sprouts can take up to 4 months to reach full maturity. In general, you can expect your sprouts to be ready for harvest between 80 and 120 days after planting. But, you may be able to see the sprouts start to form as early as 50 days after planting.
If you plant your sprouts in early spring, you can expect them to be ready for harvest around June. If you plant your sprouts in early fall, you can expect them to be ready for harvest around December.
Brussel sprouts can even keep producing well into the winter so don’t fret if they’re not quite ready by the time December rolls around.
The key to any successful Brussel sprout harvest is to have patience. Brussel sprouts can take quite a bit of time to form and may leave you wondering if they’re even going to form at all. Most likely, they will!
While golf-ball-sized Brussel sprouts are definitely the most popular and sought-after size, sprouts can be harvested at any size you want. It’s really up to you. Some people like the smaller bite-sized sprouts. They’re delicious in any size!
Reasons for loose heads in Brussel sprouts
The three main reasons that Brussel sprouts form loose heads or don’t form heads at all are likely due to one of three things. A lack of nitrogen in the soil, outside temperatures that are too warm, or plants needing to be topped due to excess leaf production.
In the next sections, I’ll go over each of these in detail and talk about what you can do to prevent or improve these conditions.
Lack of nitrogen
One of the main reasons that sprouts don’t end up forming on the plant is that the soil is lacking nitrogen, a major macronutrient. Nitrogen is responsible for most of the growth that plants do because it is a crucial element in the building of plant proteins.
But, nitrogen is a nutrient that is not readily available in the soil and therefore must be added with fertilizer application or by cover cropping with nitrogen-fixing plants.
Certain cover crops can pull nitrogen out of the atmosphere and add it back into the soil through a process called nitrogen fixation. While this method is the most natural and environmentally friendly, it is not a quick fix and can take a whole season to return your soil’s nitrogen to a good level.
The best additives you can put in your soil to raise nitrogen levels are feather meal, blood meal, and even just a good layer of compost. You can also try a general 10-10-10 fertilizer to increase the overall nutrient composition of your soil.
Not sure how much nitrogen is in your soil? A quick soil test from your local agricultural extension agency should tell you everything you need to know.
Weather too warm
Brussel sprouts are in the brassica family with other crops like broccoli, cauliflower, kale, and collards, just to name a few. The brassica family is notorious for being cold hardy and not very tolerant of hot climates.
Brussel sprouts can be especially sensitive to high heat and won’t form heads if the temps are too high. This makes summer an unideal season for sprout growing. Consistently hot weather will send the sprouts into a panic and may cause them to bolt or go to seed.
Once a Brussel sprout plant has bolted, it’s not going to put much of its energy into growing bigger sprouts anymore. All of its energy is now going toward seed production before it ultimately dies. Clipping off any flowers can slow down this process but won’t stop it completely.
To avoid this, you can either plant your sprouts in spring for an early summer harvest or you can plant your sprouts in late summer for a fall harvest. Brussel sprouts are very cold hardy so don’t be afraid that some colder nights will kill your plants.
Something that I observed in my garden one year was that after we had our first big freeze, the top leaves of the Brussel sprout plant were damaged and became very wilted and drooped over the plant.
But, what this ended up doing was creating a kind of protective tent around the Brussel sprouts themselves which were ultimately not damaged at all by the cold temperatures. I kept them on the plant for about another two weeks before harvesting them.
Many people say that Brussel sprouts aren’t good until they’ve been hit by a good frost first as this causes the plant to turn its starches into sugars as a way to survive cold temps. The result is a much sweeter sprout than you would have had without the frost.
Sometimes, Brussel sprouts can even survive a whole winter. Covering them with some kind of frost cloth will help keep them warm but even without a cover, you may find that your Brussel sprouts are still kicking it come springtime.
Plants need to be topped
To help the plant put more of its energy into sprout production, you can cut off some of the top leaves of the plant. Starting at the base of where the large leaves grow, you can cut off several at a time and slowly work your way up the plant.
Just make sure not to remove every leaf as the plant still needs these to photosynthesize. In my opinion, it’s better to prune too little than too much. You can always come back and cut more off later but you can’t put the leaves back on once you’ve removed them.
Certain varieties of Brussel sprouts actually require being topped to produce sprouts so be sure to read your seed packets carefully to determine if you’re growing a variety that needs to be topped.
Best Brussel sprout varieties for tighter heads
This variety is one of the fastest-growing sprout varieties. They take about 85 days to reach maturity and can be held in storage for up to 6 weeks.
Churchills are also known for their high yields, making them a great option for preservation through freezing or canning.
Dagan sprouts take about 100 days to reach maturity. They are known to form firm and tight heads making them a great option for holding in the field.
Very dependable and disease resistant, this variety is also much less susceptible to lodging. Lodging is just a fancy word for when Brussel sprout plants get too top-heavy and start to tip over.
Topping your plants, which I talked about earlier, can also help prevent lodging among your Brussel sprouts as it helps to remove some of the upper weight.
This variety takes about 100 days to reach maturity. They are bred for their sweet flavor but are also known to have tight and crisp sprout heads.
These stalks tend to be a bit shorter than other varieties of Brussel sprouts but they are much more disease resistant and hardy than other popular varieties.
This red variety of Brussel sprouts is truly special. Its sprouts are a rich crimson that deepens with cold. It does take 30 weeks from sowing to harvest, but it’s well worth it if you want red Brussel sprouts around Christmas. It’s a long cropping variety and your patience will be well rewarded.
Resist the temptation to grow your red sprouts too big. Small sprouts have a lovely nutty flavor and can be eaten raw too.
Not having a good Brussel sprout harvest can be frustrating. Trust me, I’ve been there. To ensure big and beautiful sprouts this season make sure that your soil has enough nitrogen, the weather’s not too warm, and remember to top your plants.
If, after all of that, you didn’t get the sprouts you were looking for this year, it’s okay. The leaves of the brussel sprout plant are also edible and delicious. So all your hard work wasn’t for nothing. If you’re a fan of collards or kale, then you’ll definitely enjoy brussel sprout leaves too.