Growing Broccoli

Romanesco Broccoli.
Latest Update 3rd November 2016.

Broccoli (Calabrese)
  • Waltham broccoli produces a firm tasty head followed by smaller floret side shoots extending harvest beyond a month.  Romanesco broccoli produces a beautiful spiraling cone shaped very pale green head, but I have never left one long enough to test whether it sends out small florets.
  • Broccoli is a healthy vegetable containing lots of dietary fibre, minerals and vitamins.
  • We don't grow many in our garden as its a seasonal vegetable and occupies a lot of limited Ecobed space.  Normally I would grow just 2 Waltham and 2 Romanesco each year.
  • I have frozen surplus broccoli in the past, but we prefer it fresh and steamed for 10 minutes with a nice dressing of a herb and vegetable based sauce. 
Waltham Broccoli.

  • Binomial Name:                                       Brassica oleracea.
  • Family:                                                    Brassicaceae.
  • Variety:                                                    Waltham and Romanesco (main head only). 
  • Crop rotation group:                                  Heavy feeders.
  • Garden bed type:                                      Garden Ecobed.
  • Recommended soil pH:                              6.0 - 7.0. 
  • Minimum sun per day:                               4 hours.
  • Plant spacings (centres x rows):                750 x 500 mm.  
  • Weeks to harvest:                                     12-20 weeks.
  • Climate:                                                   Warm temperate.
  • Geography:                                              Southern hemisphere.
  • This food is very low in saturated fat and cholesterol. 
  • It is a good source of protein, vitamin E (alpha tocopherol), thiamin, riboflavin, pantothenic acid, calcium, Iron, magnesium, phosphorus and selenium, and a very good source of dietary fiber, vitamin A, vitamin C, vitamin K, vitamin B6, folate, potassium and manganese
  • More from nutrition
Growing Conditions.
  • They grow best in full sun in the cooler months but need shadecloth protection from hot sun in the waremer months. 
  • Broccoli prefer firm, well structured soil containing plenty of organic material.
  • The soil must be kept moist at all times. 
Soil Preparation.
  • Remove old straw mulch and any other organic waste and apply a 60mm layer of hot compost.  Cover the compost with 50mm of fresh straw mulch.
Growing Instructions.
  • Sow Broccoli seeds In February on the surface of an organic seed raising mix in a mini pot, and cover lightly.
  • Soak the mini pot for 30 minutes in a tray containing 10mm of dilute seaweed extract (preferably rainwater based).  The water will wick up into the soil without flooding it. 
  • Sink the mini pots up to their rims in an Eco-propagator.  This keeps the soil moist until the seedlings are ready to transplant.
  • After 4 weeks transplant the seeds individually into organic potting mix in small jiffy pots and returned them to the propagator.
  • When the seedlings are big enough, plant them still in their jiffy pots in the prepared bed at 750mm centres along rows 500mm apart.
  • Expose a small area of soil by pushing the mulch out of the way and burying the pots deeply covering most of the plant's stem to maximise its stability in high winds.
  • Water in generously and return the mulch so that all the soil is covered.
  • Apply a foliar spray of aerated compost tea every 4 weeks with all the other edible plants.
Harvesting and Storage.
  • Harvest the broccoli from June.
  • Waltham broccoli produces a large firm head, which should be harvested before it starts to flower.
  • Allow the broccoli to continue growing and it will reward you with a succession of edible side shoots.  Harvest them regularly before they flower and they will continue to produce for several months in a warm temperate climate.
Organic Pest Control.
  • Slugs and snails.
    • Broccoli should be protected against slugs and snails using self adhesive copper tape bonded around the base of your Ecobeds.
    • If these molluscs get into your Ecobed as eggs laid in your compost, kill them with organically approved iron based snail pellets as soon as you discover them.  You should only need to use a small number of pellets.
  • Cabbage white butterfly caterpillars.
    • The best deterrent for caterpillars is exclusion netting.  My Ecobeds have built-in frames and attachments for easy mounting of exclusion netting.  However, because I grow broccoli as a winter crop, butterflies are not a serious problem, and I usually don't use the netting
    • If the butterflies become a problem spray the crop thoroughly with Bacillus thuringiensis (Dipel in Australia)  This natural soil dwelling bacterium once ingested by the caterpillars produces toxins which paralyse their digestive system causing it to stop feeding.  They die within a few days.
  • Greenhouse whitefly.
    • Whitefly breed on the backs of broccoli leaves and can be seen as 1 centimeter diameter white colonies in their pupae form.  I look for these and scrape them off with my fingernail.  If left, they will breed rapidly when the warmer weather arrives, and become a major pest in your garden. 
  • Aphids (greenfly).
    • Spray greenfly with organic horticultural oil as soon as they appear.  Be vigilant as they can return, and make sure you spray the insects themselves as the oil blocks their breathing tubes and smothers them.
  • Root knot nematodes.
    • Organically active soil is the best deterrent for root knot nematode.  The beneficial microbes protect a plant's root surfaces by colonising them, and predatory microbes control their numbers in the plant's root zone.
  • General.
    • Regular applications of aerated compost tea boost the natural defences of broccoli by colonising the leaf surfaces with beneficial microbes.  They defend the plant against airborne pests and diseases.
    • Similarly, proper soil preparation including regular applications of home made compost boosts the community of beneficial microbes, which defend the plants roots against plant pathogens.
    • Wire net tunnels stops birds digging up worms in your Ecobed, and protect the seedlings until they are large enough to withstand this behaviour.