Growing Broccoli

mmm...Broccoli. Rich in nutrients, broccoli is a tasty and healthy snack that's fun to grow and looks pretty cool while doing it. :) But did you know that both its florets and stem are edible?

Here's what we'll be covering today:

  • Glossary of broccoli terms

  • Varieties of broccoli

  • Starting your broccoli seeds

  • Caring for broccoli

  • Mulching and/or Fertilizer

  • Transplanting best practices

  • Companion Plants do’s and don’ts

  • Common problems and their solutions

  • Potential pests and diseases, plus what to do about them

  • Harvesting and storing Broccoli



  • FLORET: A flowering stem branching from the main stem of a broccoli head. These are the broccoli pieces that look like little trees!

  • COLE CROP: Vegetables from the brassica family that grow best in cool, temperate climates. Fun Fact: The word “Cole” is derived from the word “caulis”, which is the Latin word for the stem or stalk of a plant.

  • BROCCOLINI/SPROUTING BROCCOLI: A type of baby broccoli that grows in smaller, individual florets with longer stems instead of large heads.

  • ROOT BALL: The mass of soil and roots of the seedlings you transplant. We recommend that you carefully loosen the root ball before transplanting it into the ground, which will encourage those roots to develop properly.

  • BUTTONING: This is what happens when broccoli plants produce heads prematurely, resulting in poor head development. Buttoning can happen in mature plants as well, often because of water or nutrient deficiencies or high salt concentrations in the soil.

Close up of the Head of Broccoli


There are quite a few different varieties for you to choose from!


Broccoli: Arcadia Variety

A cold-tolerant variety that produces dark green heads with a signature “frosted” appearance. It’s also known to have impressive side-shoot development. This variety is not heat tolerant and takes about 60 days to mature. Marathon - An extremely cold-tolerant variety that grows well in the fall, and can be grown over winter in southern climates. This variety takes about 68 days to reach maturity.


Broccoli: Romanesco Variety

A unique, heirloom variety with light, bright green heads and beads that grow in beautiful spiral shapes. They have a unique nutty flavor that’s best when eaten raw. This variety is slow-growing, taking more than 70 days to mature.


  • Keep in mind that broccoli is most successful when transplanted, rather than being directly sown!

  • Seeds germinate in darkness, and their ideal soil temperature for germination is between 60- 85°F (16-30°C). Germination is possible in soils with temperatures as low as 40°F, but keep in mind that you might have lower success rates this way.

  • When it comes to air temperature, they can tolerate a maximum of 85°F (30°C) and need a minimum of 40°F (4.4°C). However, temperatures above 95°F (35°C) for four consecutive

  • days can damage broccoli heads and cause uneven bud development. It’s also important to note that poor soil moisture can also result in uneven bud development, while temperature extremes promote bolting and buttoning.

  • Broccoli grows best in full sun, and when its soil has a pH between 6.0-6.8. It also tends to like soils that are rich in organic matter.

  • You’ll want to start your broccoli seeds indoors about 8 weeks before transplanting. To get them started, sow 3-4 seeds per pot, or 2 seeds per cell (for a tray) at a quarter-inch deep. Once your seedlings have emerged, place your pots/trays in a window that gets a lot of direct sunlight. As your seedlings grow, thin them so that only the best plant is left in each pot/cell.

A Close up of Broccoli


In this section, we’ll tell you everything you need to know about preparing your soil, watering, fertilizer and mulch best practices, plus thinning. We’ll also cover transplanting, companion planting, and your growing structure options!


  • Keep your soil moist after seeding indoors, and water well after transplanting – in general, broccoli plants need at least 1 inch (2.5 cm) of water every 5-7 days.

  • They need consistent water for proper growth and head development, so be sure to give them enough water during dry spells.

  • It’s also important not to over-water your broccoli, as this can cause loose heads and encourage diseases to develop and spread.


  • Aside from thinning seedlings when they’re still in their trays or pots, broccoli doesn’t need to be thinned.

  • Transplanting your broccoli removes the need for extra thinning!


  • Find a spot that gets full sun with well- draining, rich and moist soil. This spot shouldn’t have been used to grow brassicas in the past 3 years.

  • Clear your bed or container of all weeds and large stones.

  • Then, turn your soil over – mixing in some organic matter as well as anything else you may need to adjust your soil’s pH or texture.

  • Finally, level and smooth the soil surface.


  • After transplanting, when your broccoli plants are about 8-10 inches (20-25 cm) tall, push the soil up around their stems to the first (bottom) true leaf. This will promote the development of side shoots!

Full Broccoli Being Held



  • Broccoli is a fairly heavy-feeder, so you’ll need to give it a nutrient boost a few times during the growing season.

  • Use a fertilizer that has a higher concentration of potassium and phosphorous, and a lower concentration of nitrogen.

  • While transplanting, add your fertilizer to the dug holes before you plant your seedlings.

  • Amend with fertilizer again once your plants are about 6-8 inches (15-20 cm) tall, and then again once they’re 12-15 inches (30-38 cm) tall.

  • You’ll want to monitor your broccoli’s head development closely, since you’ll want to fertilize your plants one last time just as the heads are forming.

  • Avoid fertilizing after head development though, because this can encourage the growth of diseases.


  • You can add a layer of mulch 1-2 inches (2.5-5 cm) thick after transplanting, to promote water retention in your soil and to discourage the growth of weeds.

  • Just remember to leave room around the stem of your plants! Too much mulch too close to the stem, it can promote fungal and bacterial growth.


  • Transplant 8 weeks after sowing, when your seedlings have at least 2 sets of true leaves (ideally, they will have 5-6 true leaves).

  • Before transplanting, though, you’ll want to first harden-off your broccoli seedlings by getting them used to outdoor conditions.

  • One week before transplanting, bring them outside, and place them in a sheltered spot where they’ll be protected from wind and harsh sun.

  • If there’s any threat of frost overnight, be sure to bring them inside. Then, simply put them back out in the morning!

  • When your broccoli plants are ready, find a spot in your garden that gets full sun and has rich soil. We recommend amending your soil with organic matter first, before transplanting.

  • Turn your soil over at a depth of 8 inches (20 cm) and then smooth the top to create an even, flat surface.

  • Then, plant your broccoli seedlings 18-24 inches (45-61 cm) apart in rows that are spaced 30-36 inches (76-91 cm) apart.

  • You’ll want to dig holes deep enough to cover the root ball, so that the surrounding soil is level with the top of the root ball. Just be careful not to damage your plants when removing the seedlings from their pots/trays.

  • Once they’re out, gently loosen the root ball before planting to promote good root development.

  • After they’re planted, firm the soil around each plant, then give your seedlings a good watering by letting water soak into the soil.

  • Broccoli plants that have been hardened-off can tolerate temperatures as low as 32°F (0°C) for up to 36 hours - and also tolerant of light frosts


Broccoli needs at least 12-18 vertical inches (30-45 cm) of soil to grow. As long as your soil is deep enough, has the required nutrients, and there’s ample space (about 30-36 inches in between plants), you can successfully grow broccoli in containers, garden beds and raised structures.

Broccoli Cut and Placed in a Bowl



  • Bush beans, carrots, celery, cucumbers, lettuce, pole beans, scallions, spinach, and Swiss chard are all great broccoli companions!

  • As well, aromatic herbs like thyme, dill, mint, rosemary, sage, and chive will help repel common pests of broccoli.

  • Onions improve broccoli’s flavor, while crops like beets don’t mind broccoli’s tendency to hog calcium in the soil.


  • Peppers and tomatoes prefer acidic soils, so they shouldn’t be planted in the same soil as broccoli, which prefers more neutral soils.

  • As well, strawberries and squash are heavy feeders like broccoli. That means your soil can’t support both at the same time, and either one or both crops will end up struggling.

Broccoli Pulled Apart into a Smaller Piece


There are a number of issues, pests, and diseases that can potentially harm your broccoli plant. Not to worry – we’ve listed them below, as well as how to either avoid or fix the problem.

  • BUTTONING: When broccoli plants produce their heads prematurely, so they’re not well-developed.

  • HOLLOW STEM: When gaps form in the inside stem tissue, which then slowly get bigger.


  • CABBAGE MAGGOT: Also known as the cabbage fly, adult flies lay eggs on the lower parts of broccoli plants. The larvae tunnels into the root system to feed, stunting the growth of your broccoli plant.

  • APHIDS: These tiny pests come in a variety of colors (mostly green, though they can also be yellow, pink or even black) and mainly feed on the undersides of leaves. Sometimes, they also feed on stems and broccoli heads. What they’re actually feeding on is the sap in your plants, which ends up damaging your plants.

  • CUTWORMS: These pests are grey worms that chew on the root and shoot systems of broccoli plants.

  • FLEA BEETLES: These are small black beetles that feed on seedlings and jump when they’re disturbed. Their feeding damage can potentially kill your young broccoli seedlings.

  • CABBAGE LOOPER: The caterpillar that can cause the most amount of damage to your broccoli. They’re green with two white stripes running down their backs, and feed on your plant’s leaves.

Heads of Broccoli



  • This fungus lives in the soil and causes deformed roots, which then leads to poor water and nutrient uptake by your plants.

  • Clubroot can actually remain in your soil for as long as 10-20 years under the right conditions – which impacts the growth of your Cole crops for many seasons.

  • To limit its growth, make sure not to plant brassicas in your soil for 7 years. Disinfect all equipment used on the infected soil, and amend your soil to raise its pH, since clubroot thrives in moist acidic soils.


  • A fungal infection that leaves patches of white fuzz on the undersides of leaves, stems, and broccoli heads.

  • As the disease spreads, there might also be dark streaks that show up inside of your broccoli heads, while leaves will change from purple to yellow or brown.

  • If you’re looking to avoid this disease, Gypsy broccoli is one variety that has some resistance to downy mildew.


  • A soil-borne fungus that’s known to cause damping-off and wirestem in broccoli.

  • Damping- off can cause seeds to decay in infected soil, or it can cause seedlings to unexpectedly wilt and break.

  • Wirestem is a continuation of the damping-off process, and causes the stem to decay. Wirestem might not kill your plant, but it will likely affect its growth and quality.


  • This is caused by a soil-borne bacteria that reaches the broccoli head.

  • Instead of water forming droplets on the waxy coating, florets will appear water-soaked, and they might also have black lesions and appear sunken.

  • To avoid this issue, you’ll want to make sure you avoid having high nitrogen levels in your soil especially after your broccoli’s head development.


  • A soil-borne bacteria that causes lesions around the outsides of leaves.

  • These lesions turn yellow and travel inward on the infected leaves, typically in a V shape.

  • Leaf veins will then turn dark, and the stems of your broccoli plant might become discolored as well.


Follow these easy tips to significantly reduce the risk of diseases affecting your broccoli!

  • Practicing crop rotation is really important with brassicas in order to avoid diseases. What crop rotation means is that you do not plant broccoli in soil that has been used to grow another brassica in the past 3-4 years.

  • As well, plant with certified disease-free seeds or transplants when possible. Control all the weeds around your broccoli crop, but especially weeds from the mustard family.

  • It’s also very important to follow the recommended spacing – this ensures good air flow around your crops.

  • Finally, broccoli needs to be planted in well- draining soils and watering should be done in the morning to give them enough time to dry off during the day.

Broccoli in Colander


  • Once the head has fully developed (when compact buds have formed, but before they have flowered), harvest the central head with at least 6 inches of stem attached to it.

  • You’ll want to use a tool with a sharp blade to do this. By removing the central head, it will encourage smaller heads to grow, which can then be harvested later on.


Broccoli can be enjoyed either raw or cooked!

  • For fresh consumption, store your broccoli for 3-5 days unwashed, in a loose bag, in your fridge’s crisper. It’s important that your broccoli is dry when refrigerated because if it’s wet, it becomes soft and prone to mold.

  • Broccoli can also be stored in the freezer to be enjoyed later. Cut your broccoli into florets, blanch them in hot water, then store them in airtight freezer bags.

  • Keep in mind that broccoli is sensitive to ethylene, a ripening hormone/gas that’s produced by some fruits like apples and bananas – so just make sure to store your broccoli away from these fruits!

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