Broccoli is one of my favorite vegetables. I love cooking with it, growing it, and eating it. When I was a child, I loved devouring it because I felt like a brontosaurus munching trees. To be honest, I still kind of feel like a dinosaur eating the tiny broccoli trees.
Growing broccoli is usually pretty straightforward. It has simple needs and grows quickly. But occasionally, growing broccoli can present a gardening challenge.
One of the most common and most frustrating problems when you’re growing broccoli is “buttoning” – and the brontosaurus ends up eating stubbly shrubs instead.
What is Broccoli Buttoning?
Properly grown, broccoli plants produce a large head with thick florets growing out from one large stalk. This thick, green “tree” of broccoli is technically the flowering part, but we harvest it before it blossoms. This head is what we want to produce in our gardens.
But in the wrong conditions, your broccoli plant will “button up” and the head won’t form properly.
Instead of producing a large head with close, thick branches that create the classic compact broccoli head, buttoned broccoli produces multiple small, separate branches that are spread out.
You don’t have one compact head when broccoli buttoning happens. Instead, you have multiple smaller, button-like heads that will never merge into that marvelous head that we all want to see.
When broccoli buttons, you get less harvestable broccoli, and the visual quality is reduced. No one is buying your heads at the farmer’s market when your broccoli is buttoning.
Broccoli buttoning is different from bolting. Bolting is when the head goes to flower. Buttoning might also involve bolting, but it’s a separate issue and one that is often caused by some of the same things.
5 Causes of Broccoli Buttoning
Broccoli buttons either because it lacks the nutritional resources to produce a compact head or because it is trying to produce at least a few small heads that will survive to reproduce.
When young broccoli is missing out on some important nutrients or is undergoing environmental stress, it will often button up. Moisture issues, the wrong temperatures, and other stressors can cause broccoli buttoning.
We’ll talk about temperature first.
1. Temperature
One primary cause of broccoli buttoning is temperature. Broccoli does best when the temperatures stay between 40-80°F. If it dips below this or climbs above this, especially when the broccoli is still young and developing, broccoli buttoning may occur.
A surprise drop in temperatures when plants are young can impact developing heads. Hot summer temperatures can also cause buttoning and bolting. If you plant your broccoli in summer, the heat will damage broccoli’s ability to form healthy heads.
If your growing season is short and there are extreme temperature ranges, you may need to bring shade covers to protect your plants from both the cold and hot sun. You might also want to start them indoors to give them a longer growing period in the right temps.
2. Nitrogen
Another cause of buttoning is excess nitrogen in the soil. Nitrogen is an essential nutrient for plants and is included in most fertilizer blends.
The letters NPK on fertilizer bags refer to the macronutrients nitrogen (N), phosphorus (P), and potassium (K) – essential parts of every healthy plant’s diet. But each plant has different nutrient needs. And soil varies from place to place.
Some plants, such as peas, make their own nitrogen. However, some gardens already have a lot of nitrogen in the soil, and adding more will just overload it.
Sometimes, too much of a good thing can be damaging.
When broccoli has too much nitrogen in the soil, it can encourage buttoning. This is because nitrogen tends to support leaf growth over flowering.
So, your broccoli plants are getting too much of a leaf boost and not enough phosphorus and potassium to encourage healthy flowering. A 6-8-8 fertilizer is perfect for keeping your broccoli plants nourished but not giving them too much nitrogen.
But before you even consider fertilizing, you should test your soil. There’s no point in adding 6-8-8 food to your soil if it’s already full of nitrogen and completely devoid of phosphorus. Soil testing is cheap and provides a ton of insight, so don’t skip it.
3. Watering Issues
Doughts stress out many plants. Broccoli is no exception. When your plants don’t have enough water, they do the bare minimum to survive. That means that when it comes to producing flowering heads, your broccoli plants will produce fewer, smaller heads.
In other words, a lack of water during the growing process is a sure road to broccoli buttoning.
Broccoli plants need regular watering. They do best in rich, well-draining soil that receives consistent watering to maintain a moist but not sodden moisture level. The soil should feel like a well-wrung-out sponge at all times.
Broccoli plants have a shallow, small root system, so they can’t dive deep into the soil to find water. They need easy-to-access moisture in the topsoil. Without it, broccoli plants will be stressed and will not produce the compact heads you want.
Over watering can also cause stress to your plants. If you’re having a wet season, you may want to cover up your broccoli plants to allow the soil time to dry. If the soil is moist from rain when it’s time to water, delay your watering a day or two and then check again.
To check the soil, stick your finger into the soil. Even if the surface soil is dry, the soil right under the surface may feel wet to the touch. If so, wait a day or two and test again. Don’t let the soil dry out completely, but wait to water until the soil feels cool and slightly moist, not wet or waterlogged.
4. Exessive Salts
All soils contain salts, which are a natural part of the earth’s makeup. Depending on the region you live in and the geologic history of that soil, you could have very salty soil or depleted soil. Salts also enter the soil through irrigation and fertilizing.
A little salt in the soil is great for soil health. However, too much salt can produce a stressful growing environment for your plants. Remember, stress can cause broccoli buttoning.
If you see signs of stress in your garden, including broccoli buttoning, but don’t know why, get the soil tested for excess salts. Most local extension offices will do this for cheap.
If you have excess salts, you may have to amend the soil significantly to fix the problem, or you could start growing in containers or raised beds with healthy soil until you can gradually fix the issue.
Removing excess salt from your soil is a long-term project and one that sometimes requires professional support. That’s okay. Raised beds and containers are an excellent option for growing broccoli.
5. Transplanting Stress
Sometimes, starting seeds indoors is the best way to give them enough time to thrive. But other times, the process of transplanting can stress the plant. If the plant is stressed when it’s young, broccoli buttoning may follow.
Broccoli plants do well when started indoors, but they can also button up if the transplanting is done too late or too roughly for the plant to tolerate.
If you’re starting broccoli plants indoors, there are a few ways to protect your plants from transplant buttoning. First, don’t wait too long to transplant. Don’t wait til your young broccolis are root-bound in their pots or halfway to heading up.
Consider starting broccoli seeds in decomposable pots, so you can just plant the whole pot in the soil. That will reduce the stress your broccoli plants are under. CowPots are an excellent option because they’re made out of manure and readily decompose in the garden while adding nutrients. Grab a pack at Amazon.
Water well during and after transplanting. Ideally, transplant on a cloudy day when the weather is not too hot or too cold. Be sure to harden off your plants before transplanting to prevent shock.
Hardening off is an easy process. It’s simply the process of gradually introducing your plants to the more extreme conditions of the outdoors. Your plant is used to the easy life inside, and it needs to be toughened up a bit.
Learn about the process in our guide.
Other Stressors in the Garden
Because broccoli buttoning is primarily a stress response by the plant, it can happen for a variety of reasons. The causes above are the most common, but anything that stresses your plant can result in broccoli buttoning and those small, separate heads.
Diseases, heavy pest infestations, weeds, poor soil, and other stressors can also cause your broccoli plants to button. Do your best to support your plants and prevent this issue.
Preventative Care
When it comes to gardening, the best offense is a good defense. Start by building a garden that can nurture the plants you want to grow.
Keep your garden clean, remove plant debris, weed regularly, and test the soil before you plant. If you find imbalances in your soil test, take the time to build up the soil before you bring in plants.
Remember that when and where you choose to plant depends on your particular climate. If you live in northern New England, like I do, a March planting will almost certainly be buried in snow.
But in Alabama, March may be the best season to get your broccoli in the ground before the summer heat makes the garden too stressful for your sensitive plants.
If you’re growing in a hot climate, use row covers to offer sun protection for your plants. If you’re growing in the cool north, use row protection to keep the chill away.
Remember to water weekly. Give your broccoli plants a heavy soaking of water, about two inches, each week. If you get over an inch of natural rainfall in the course of a week can you skip the weekly watering.
Of course, if you have a wet growing season and regularly get over an inch of water each week, your plants are fine. Don’t overwater by continuing to soak your broccoli plants weekly, despite abundant rain.
Can I Eat Buttoned Broccoli?
You can eat buttoned broccoli. Unfortunately, it tends to have a poorer flavor. Buttoned broccoli can taste a little bitter and tough. Often, gardeners who end up with buttoned broccoli treat it like boccoli-rabe and cook it with plenty of garlic to improve the taste.
Using buttoned broccoli in flavorful soups is another way to minimize the disappointing flavor without wasting produce.
Don’t try to sell buttoned broccoli at a farmer’s market unless you’re willing to sell it at a discount and are clear about the downsides. Honesty and transparency are the best ways to deal with market customers, build trust, and find ways to use up less-than-ideal produce.
For more tips on standing out at the farmer’s market, visit our guide.