This is the most detailed and comprehensive guide on broccoli growing. Besides planting you’ll also find caring tips including choosing the best variety, potting mixes, propagation, planting time, fertilizer application, and much more.
Broccoli is a cool-season crop that is best grown in the spring or fall. As a biennial plant, it can overwinter in mild climates and provide a spring harvest.
The crop is rich in minerals and vitamins and is a good source of Vitamin A among other essential elements. Besides, broccoli is one of the easiest vegetables to grow for beginners, producing bluish-green heads that are harvested in the summer or autumn, depending on the time it is sown.
If you would like to learn how to grow and care for this nutritious Cole crop, then you’ll love this article.
Let’s get started:
Tips for Broccoli Growing and Care
1. Use appropriate potting mix for growing broccoli
Broccoli growing is best done in well-drained soils with a texture between sandy and clay loam. However, the soil must be rich in compost and its pH should be between 6.0 and 6.8.
Amend your potting mix with 10-10-10 (NPK) fertilizer as you follow the directions on the package for best performing pot-growing broccoli. On the other hand, amend your garden soil with well-rotted manure or compost to help conserve moisture and increase soil porosity.
The compost amends the soil naturally as it breaks down, releasing important macro-and micronutrients while feeding the beneficial biological organisms in the soil. Moreover, the slow release of nutrients from compost enhances the healthy growth of your broccoli.
Learn how to improve the drainage of your potting soil.
2. Pick the right broccoli variety
The type of broccoli you grow is determined by where you grow your broccoli. If you are growing broccoli in containers/ indoors, you should go for the fast-growing/ maturing broccoli varieties such as De Cicco, Waltham 29, or Atlantic.
This way, you will be able to maintain an efficient container garden in which you can harvest full-size broccoli heads in approximately 50-65 days from sprouting.
For growing broccoli outdoors, you need to first consider the weather in your area, then select the appropriate broccoli variety. For example, the Belstar variety is good for the south (more temperate climates), or the Eastern Magic broccoli variety for the North-Eastern region of North America.
3. How to propagate your broccoli
There are 2 ways in which you can propagate your broccoli.
Broccoli propagation by seed
This is where knowledge on USDA hardiness zones comes in handy. For example, if you are in zones 3 and 4, you need to sow your broccoli seeds indoors 6 to 8 weeks before the last frost date and, transplant the seedlings outdoor 5 to 6 weeks later.
In zones 5 and 6, direct sow your seeds in spring as soon as the land is workable. As for zones 7 to 9, we recommend that you sow your broccoli seeds 3 to 4 months before your first frost date (fall sowing)
Check out the Quick Gardening Tips for Zones 4 to 9
Vegetative propagation of broccoli - e.g. from stems
In this case, cut the stalks off and then cover the roots with water without submerging the top of the cutting. Keep the top of the cutting moist by occasionally misting it with water.
Leave the cutting in a sunny location with their roots in clean water. After a few days (about a week), new leaves and roots will appear. You can then transplant the young plants in the garden or into a container.
4. Plant your broccoli at the right time
Broccoli is a cool weather plant. Therefore, plant your broccoli in early spring or mid-to-late summer. These cool-season plants get stunted under hot temperatures hence your goal should be to harvest mature broccoli before or after high summer temperatures.
Should you go for a fall planting of broccoli, sow your seeds outdoor in about 80 to 100 days before the first fall frost. This time the soil temperatures are high and this helps in speeding up seed germination and development. Alternatively, start your seeds in late May.
For spring planting of broccoli, start your seeds outdoors or indoors a few weeks before the last spring frost date. To start your broccoli outdoors, sow the seeds outdoor 2 to 3 weeks before your last frost date (or as soon as the soil can be worked on). As for starting broccoli indoors in spring, start seeds indoors 6 to 8 weeks before your last frost date.
5. Prepare the planting site for your broccoli
Broccoli requires exposure to full sun therefore, select a site where your broccoli will be able to get at least 6 hours of sunlight a day otherwise they will produce thin, leggy plants with weak heads.
Then work in 2 to 4 inches of rich compost or a thin layer of manure in early spring to increase fertility before you plant your broccoli.
If you started the seeds indoors, plant 4 to 6 weeks old transplants(have 4 or 5 leaves) outdoors at a spacing of approximately 12 to 20 inches apart. Make sure the planting holes are slightly deeper than the transplants’ container depth.
For outdoor starting of broccoli, sow the seeds in ½ inch deep holes at a spacing of 3 inches apart. Once seedlings reach approximately 2 to 3 inches tall, thin them out such that plants are approximately 12 to 20 inches apart.
Pro Tip: Broccoli rows should be 3 feet apart otherwise your broccoli will produce smaller main heads and more secondary heads.
6. Water your broccoli regularly
Broccoli plants like steady moisture for fast and healthy growth, so apply about 1 to 1.5 inches of water per week. This applies to both container-grown broccoli and those grown outdoors but remember to regularly check your potted plants as they tend to lose water faster than those in the garden.
Keep the soil moist always but never soggy.
To check if your broccoli needs water, stick your finger about an inch into the topsoil. If it feels moist, you don’t need to water the plants but if it feels dry, you need to water your broccoli.
Skip watering for a few days whenever it rains and move your container grown broccoli to a sheltered place when there is a heavy downpour. This way the soil won’t be waterlogged.
Add a layer of organic mulch of compost, finely ground leaves, or finely ground bark to help keep the soil cool and moist especially when temperatures heat up. A light-colored mulch like straw also helps reflect heat away from the soil thus creating a cool environment for your broccoli to thrive.
On the other hand, when its’ too cold (in a cold climate), you may need to plant your broccoli through black plastic in early spring to help warm the soil and do not mulch.
7. Fertilize your broccoli
Broccoli is a heavy feeder hence a dose of well-balanced fertilizer every couple of weeks is important for good performance. Therefore, use a balanced granular fertilizer for example 14-14-14- or 10-10-10 (at the rate recommended by the manufacturer) when the transplanted seedlings are about 4-5 inches tall.
Scatter the granules around the broccoli plants without letting the granules touch the plant as they might burn them. Make sure you water your broccoli well after fertilizer application for uniform absorption.
Another way to fertilize your broccoli is to use a water-soluble fertilizer. Mix the fertilizer in a watering can or a hose-end sprayer as per the manufacturer’s instructions and apply it when you water your broccoli. You should do this as soon as you transplant your broccoli.
Interested in growing broccoli organically?
It is important to first work some well-rotted manure or compost into the soil before planting to improve soil fertility as well as soil structure.
Then use a balanced organic fertilizer or fish emulsions to fertilize your broccoli plants.
Mulching is critical to broccoli growing since broccoli likes cool soil.
Mulch is very helpful in maintaining soil moisture and protects your broccoli from drying out quickly. It also helps in suppressing weeds thereby reducing the weeding frequency thus protects the plant's roots from getting damaged during weeding. Here’s a list of the best weed killers for the garden.
Organic mulch such as pine straw and shredded dry leaves is common to most gardeners and it has shown to work well in broccoli.
9. Plant other beneficial plants alongside your broccoli
Intercrop your broccoli with carrots, celery, cucumber, chard, beet, bush beans, peas, and lettuce to create a harmonious garden for higher yields and improve disease resistance. Also try growing strong-scented herbs like basil, rosemary, mint, garlic, thyme, dill, and sage to help repel pest insects that may attack your broccoli.
Note: We recommend that you check with the companion planting chart before interplanting your broccoli.
10. Control pests and diseases
Common pests in broccoli
Aphids – Aphids are tiny insects that feed on the underside of the broccoli leaves causing them to be wrinkled and discolored. Control aphids in broccoli by use of strong water spray from a hose. But under severe infestations treat your broccoli with neem oil or insecticidal soap.
Cabbage worms– These include the larvae of moths and butterflies. Cabbage worms feed on broccoli leaves causing serious damage. Control young cabbage worms’ larvae on broccoli by spraying the plants with an insecticide that contains spinosad or Bacillus thuringiesis.
Flea beetles – Flea beetles are tiny, black insects that feed on the broccoli leaves, leaving behind numerous small holes on the foliage. Use a flea beetle insecticide to control these pests. Learn how to get rid of flea beetles.
Common diseases in broccoli
Alternaria leaf spot – This is a fungal infection that is characterized by small round or angular dark spots on the leaves. To control Alternaria leaf spot in broccoli, use pathogen-free seeds, practice crop rotation and apply an appropriate fungicide.
Club rot – Just like Alternaria leafspot, club rot is a fungal infection that causes slow plant growth and stunted growth. It also leads to distorted and swollen roots. To manage club rot in broccoli, you must avoid field-grown transplants unless they have been produced in a fumigated bed. In addition to this, make sure to use certified broccoli seeds only. You can also apply lime to the soil to reduce fungus sporulation.
Powdery mildew – This is a fungal infection that causes small white patches on the lower and upper sides of broccoli leaves. These patches then coalesce to form a dense powdery coating on the leaves and lead to leaf chlorosis. Apply sulfur sprays, dust, or vapors along with regular weeding and crop debris removal for powdery mildew management.
Damping-off (wirestem) - Wirestem is a fungal infection that causes seedling death after germination. The seedlings may remain upright but the stems are constricted and twisted. To manage damping-off in broccoli, use disease-free seeds or use transplants that have been produced in sterilized planting media/soil.
11. Harvest mature broccoli at the right time
Before you harvest your broccoli you need to check if it has reached its peak size and texture. Closely monitor your broccoli when the center head starts to form.
The tiny buds that make up the head should remain tightly closed and as the buds begin to swell up, you should be able to see some yellow peaking underneath the buds. This is the right time to harvest your broccoli regardless of the head size.
To harvest your broccoli, use a sharp knife to cut the head at its base and leave the plant to produce small side shoots. These can be harvested and eaten as well or leave them to form small heads and harvest them as soon as the buds start to swell.
After you have harvested the main head (main head harvest) and the side shoots (side shoot harvest), you can now uproot your broccoli and dispose of them.
12. Post-harvest handling of broccoli
Once you have harvested your broccoli, you can either eat it right away or store it in a refrigerator with its heads intact. Sometimes you have a large broccoli crop and to preserve it, it needs to be frozen.
First and foremost, cut the florets off the head and blanch them in boiling water for approximately 2 minutes. Then dip them in ice water for 2 minutes. Drain the florets and put them in an airtight bag/container in the freezer. This will preserve your broccoli for up to 6 months.
13. Common physiological problems in broccoli growing
Broccoli bolting (growing tall and flowering)
Bolting in broccolis is caused by too much heat. Broccoli is a cool weather plant and when the soil is too hot, your broccoli will start to flower earlier than it should be(bolt).
To prevent your broccoli from bolting, always keep your soil cool by frequent watering or by use of a thick layer of mulch on the topsoil around the plants. This helps to keep the roots cool even when the weather heats up.
You can also use row covers to keep sunlight from directly hitting the soil and plants too strongly. Although row covers may slightly slow down your broccoli’s maturation process, they drastically affect the soil temperature and keep your plants from bolting.
This helps keep your broccoli producing for long.
The final and most efficient way to prevent your broccoli from bolting is to harvest your broccoli early and more frequently. Since broccoli is a cut and come again vegetable, it will produce side heads after cutting the main head and these side heads take time to bolt.
Yellow broccoli heads
Like I mentioned earlier, broccoli is a heavy feeder plant and requires high levels of nitrogen. If your broccoli doesn’t get enough nitrogen from the soil, it’s leaves begin to turn yellow.
With nitrogen deficiency, the bottom leaves of your broccoli turn first and the yellowing continues upwards toward the head. Extreme nitrogen deficiency in broccoli leads to yellowing of the entire plant and eventually the plant wilts and dies.
To treat the yellowing of broccoli due to nitrogen deficiency, use a fertilizer that is high in nitrogen and low in phosphorus as you follow the manufacturer’s instructions. For your organically grown broccoli, fertilize the plants with bloodmeal.
Yellow heads in broccoli can also be an indication of maturity (maturity yellowing). Upon maturity, the tiny buds that make up the broccoli head start to swell and if not harvested on time, the heads become more yellow until the flowers burst forth. Therefore, do not wait for so long to harvest your mature broccoli.
Leggy seedlings in broccoli
Broccoli seedlings become leggy when the stems are long, thin, and are unable to hold the plant. There are several causes of leggy seedlings in broccoli including; too much nitrogen that causes the seedlings to produce weak sprouts and, exposure of your broccoli to low light levels.
To prevent leggy seedlings in broccoli resulting from high levels of nitrogen, add a fertilizer that is rich in phosphorus and low in nitrogen, then water your broccoli well and frequently. Also, make sure to place your broccoli in a site that receives at least 6 to 8 hours of sunlight a day.
Broccoli buttoning occurs when a young plant is forced to prematurely enter its reproductive stage. When this happens, your broccoli produces several small buttons–like heads that never mature into one large- tight head.
There are several causes of broccoli buttoning including; exposure of young broccoli plants to several days of cold temperatures (below 40 degrees F), excessive salts in the soil, weed competition, insufficient soil moisture, pests, and diseases as well as too much nitrogen in the soil.
Spindly broccoli (broccoli with loose heads)
Spindly broccoli is characterized by the formation of loose, separate florets, rather than a single solid head. This is caused by fluctuating temperatures, nutrient imbalances, poorly timed planting, fluctuating soil moisture levels and, nutrient imbalances in the soil.
It is therefore important to use well-balanced fertilizers for your broccoli and at the same time, ensure that your plants get the micro and macronutrients that they require. Also, try as much as you can to maintain uniform temperature and moisture levels around your broccoli at all times.
Broccoli not forming heads (producing small heads)
Is your broccoli not forming heads or producing small heads? The reasons for this are many but one of the most common is timing.
Broccoli likes to be kept cool, therefore, set your broccoli in the early spring for a summer harvest and/or in the early fall.
Other reasons why your broccoli won’t head at all includes; overcrowding, damages to the root system (or transplanting seedlings too late with roots that are root bound)
I hope your broccoli growing journey won’t be the same after reading this article.
My last advice would be to bookmark this resource or save it on Pinterest so that you can always refer to it.
There’s so much information included ranging from how to choose the best broccoli variety, deciding the potting mix, propagation, fertilizer application, physiological disorders, and their management.
It is, therefore, impractical to grasp everything in one read.
All the same, I hope you’ve found these 13 tips for broccoli growing helpful. Let me know what you think in the comments and happy gardening!