Wednesday, February 20, 2013

How to Grow Broccoli in the North

Coronado Crown
Broccoli grows very well in the north because it’s a cool-season vegetable but due to the short growing season, it’s important to choose an early variety. (See below) It’s best to use nursery bought transplants or start seeds indoors. I’m happy to report that last year I harvested broccoli well into November before my plants died off.

Plant Type: Annual
Genus: Cabbage Family
Name: Brassica oleracea
Zones: 3-10

How to Start Broccoli Seeds Indoors

Supplies Needed

  • Starter Trays or Pots
  • Broccoli Seeds
  • Mix of Sandy, Loamy Soil w/Organic Matter


  • Start broccoli  indoors 2-3 weeks before last spring frost
  • Fill trays or pots ¾ of the way with soil
  • Plant 2-3 seeds per pot according to depth instructions on back of seed packet
  • Loosely top with soil
  • Water 
  • Keep seedlings watered. If soil hardens and cracks, water more often
  • After seedlings sprout, thin to 1 per pot or every 1-1 ½ inches
  • Harden off broccoli seedlings at 6-8 weeks old before transplanting outdoors

How to Grow Broccoli Outdoors

When to Plant: Transplant up to 2 weeks after last scheduled spring frost

Light Requirements: Full sun

Soil Type: Mix of loamy/sandy soil mixed with compost or year-old manure

Spacing: Space broccoli seedlings 24” apart - do not cage

Watering: Keep soil moist and well-watered. Spare heads while watering to prevent rot

Fertilization: Fertilize with organic matter 3 weeks after transplanting

Weeding: Take care when weeding to not disturb shallow broccoli roots

Mulching: Mulch 2-3 inches around and in between broccoli plants to keep weeds down and retain moisture in soil. Mulch also helps keep soil temperatures cooler

Garden Pest and Disease Control

Imported Cabbageworms: Look for larvae (caterpillars) that are green in color with  yellow stripes down their backs. Adults are 1 ½ inch butterflies. Imported cabbageworms leave behind large holes in broccoli leaves and green-black frass (droppings). Handpick worms and cocoons from backside of leaves and drown in soapy water.

Cabbage Loopers: Larvae are 1 ½ inch long worms with two white or yellow lines down their backs. Control using the same method as imported cabbageworms.

Aphids: Look for tiny, pear-shaped yellow, green or brown insects with long antennae and legs. Treat by spraying with a mixture of 1 tablespoon vegetable oil and ½ teaspoon of liquid soap mixed into a quart of water (shake well before using).

White Flies: Look for powdery-white, ½0 of an inch long flies on the undersides of leaves. They leave behind clusters of white rings with dark centers. Control with yellow sticky traps or insecticidal soap.

Flea Beetles: Adults are 1/10 of an inch long and bronze, brown or black in color with long legs. They leave behind lots of small holes in broccoli leaves. Gently cultivate soil around plants to kill flea eggs. Control adults with floating row covers.

Downy Mildew: Look for yellow patches on leaves. Mildew is typically caused by too much moistness. Avoid spraying broccoli leaves when watering. Plant downy mildew resistant varieties.

Nitrogen Deficiency: Leaves yellow starting at the bottom and working up. Treat deficiency with composted manure, a fertilizer high in nitrogen but low in phosphorus or Blood Meal.

Clubroot: Caused by a fungus. Stop fungus from spreading by digging up and removing all broccoli roots and tendrils. Place in plastic bags and dispose - do not add to compost or fungus may be left behind. Test soil pH and raise above 7.2 if need be.

How to Harvest Broccoli

Harvest the main heads of broccoli while buds are tight and before they yellow or flower. Cut stems at a slant 5 inches below heads with a sharp knife. Continue cutting all side shoots to encourage an extended harvest.


Rinse and dry heads before storing in fridge for up to 5 days. Blanch and freeze up to a year for longer storage.

Last year I had what I thought was a bright idea at the time. After transplanting my seedlings in the garden, I placed a tomato cage around each plant. My reasoning was, since broccoli plants have shallow root systems and mature plants tend

Related Articles

Apollo Broccoli
There are plenty of broccoli varieties to grow in the north. The best one’s have shorter days to maturity. Always start seeds indoors 4-6 weeks before the average last frost date or buy transplants from the local plant nursery for a healthy and productive harvest in the north.

Mini Broccoli Varieties (Broccoli X Gailon)

Happy Rich: Produces large florets sweet in flavor. Plants are dark green with lots of side shoots. 55 days.

Atlantis: High yield potential. Florets are even bigger than “Happy Rich.” Harvest mature head to encourage side shoots to grow for an additional 4-6 weeks. Slightly sweet flavor. 60 days.

Broccoli Raab Varieties

Sessantina Grossa: Early variety. Shoots and buds are thick and tender, resembling “mini” versions of full-sized broccoli. Best when used for an early harvest. 35 days.

Spring Raab: Best pick for growing and harvesting all season long. Large plants mature late. Great for pairing with Sessantina Grossa for extended harvest. 42 days.

Spigariello Liscia: Leaf variety grown similar to broccoli raab. Individual leaves or bunches can be harvested. If left to mature, mini broccoli heads will form. Sweeter taste. 45 days, 70 days for mini heads.

Full-Sized Broccoli

Green Goliath: Great garden variety. Produces bluish-green heads with tight buds and lots of side shoots. Large heads can be harvested over a 3 week period. 53 days.

Calabrese: Heirloom variety. Produces dark, bluish-green heads averaging 5” across on large 30-36” plants. 60-90 days.

Green Duke: Great southern variety. Vigorous grower producing high yields of dome shaped heads. Tolerates heat well. 70 days.

Broccoli Hybrids

Blue Wind: Early variety. Produces medium-sized blueish green heads. Uniform in size. Easy to harvest. 49 days.

Flash: Early variety. Produces bluish-green heads sweeter in flavor than most. Tolerates heat and Downy mildew. 50 days.

Amadeus: Early variety. Produces medium-sized heads blueish-green in color. Produces lots of side shoots. Attractive heads look good at markets with fine beads and uniform shape. Plants are medium-sized and vigorous. 56 days.

Green Magic: Early variety. Produces smooth, uniform heads that are attractive to look at in markets. Plants are medium-sized. 57 days.

Packman Broccoli
Packman Broccoli: Early Variety. High-yielding. Produces  8” dark-green domed heads with medium-large beads. Lots of side shoots. Freezes well. Tolerates heat. 57 days.

Premium Crop: Early variety. Produces 9” heads with tight beads. Plants can grow up to 2’ tall. Flavorful. 58 days.

Gypsy: Early variety. Produces uniform, well-domed heads with a medium-large bead size. Stems are medium in size. Produces a good amount of side shoots. Plants grow large and resist downy mildew well and have a good heat tolerance. 58 days.

Coronado Crown Broccoli
Coronado Crown: Great northern/southern variety. Produces solid, dome-shaped heads with tender, stringless stems. Produces lots of side shoots. Tolerates heat well. Freezes well. 58 days.

Green Magic: Produces blueish-green heads uniform in size and full of flavor. Tolerates downy mildew. Freezes well. 60 days.

Bay Meadows: Adaptable variety. Produces blueish-green heads with good domes. 60 days.

Arcadia: Cold variety. Produces firm, dark-green heads with a frosted look. Grows vigorously maturing mid to late season. Resists downy mildew, head rot & brown heads. Tolerates stress and cold well. 63 days.

Batavia: Produces dark-green heads with tight, medium beads. Adapts well. Resists powdery mildew. Heat and cold tolerant. 65 days.

Belstar Broccoli
Belstar: Adaptable variety. Produces medium-green heads with good domes and medium beads. Good shoot production. Tolerates stress well. 66 days.

Diplomat: A great variety for the north. Produces dense, dark-green heads medium-large in size with small beads. Good for bunching or crown cutting. Resists downy mildew well. 68 days.

Marathon: Fall/winter variety. Matures late in the season. Tolerates cold very well. Harvest in late summer and fall. 68 days.

Apollo: A cross between Calabrese and Chinese Kale. 24” tall plants are great for small gardens. Produces long, tender stalks. Harvest main head for lots of side shoots. Heavy producer. 80 days.

Open Pollinated Broccoli

De Cicco: Italian variety. Produces clusters of 3-4" main heads and lots of side shoots for an extended harvest. Good for spring and fall production. 48 days.

Resources: Johnny's Selected Seeds, Gurney's Seed and Nursery Co., Park Seed Co., Generic Seeds 

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