Growing Turnips

Latest Update 21st July 2016.

Turnip
  • Turnips are best harvested young (50mm to 75mm in diameter), when the roots are at their most tender and the foliage can be used as a leafy green vegetable.
  • I like to steam or roast the young turnip roots, but I leave some to mature for use in soups and casseroles.
  • Organically grown turnips are full of flavour and very nutritious.
  • I grow a few succession crops from late summer to late autumn.
  • I only grow 2 or 3 turnips at a time, and use them as required in the kitchen.  I don't store them for later use.
  • In my garden, turnips are rarely affected by pests or diseases. 
Details 
  • Variety:                                                    Purple Top White Globe.
  • Trinomial name:                                        Brassica rapa var. rapa
  • Family group:                                           Brassiaceae.
  • Crop rotation group:                                  Heavy feeders.
  • Garden bed type:                                      Garden Ecobed.
  • Recommended soil pH:                             5.5 - 7.0.
  • Minimum sun per day:                               6 hours.
  • Plant spacings (centres x rows):                150 x 150 mm.
  • Weeks to harvest:                                     6 - 9 weeks.
  • Good companions:                                    Peas, nasturtiums.
  • Climate:                                                   Warm temperate.
  • Geography:                                              Southern hemisphere.
Nutrition.
  • This food is very low in saturated fat and cholesterol. 
  • It is a good source of vitamin B6, folate, calcium, potassium and copper, and a very good source of dietary fiber, vitamin C and manganese.
  • More from nutrition data.self.com.
Growing Conditions.
  • They grow best in full sun in cooler months, and like to be shaded from hot sun in summer
  • They prefer well structured firm soil containing plenty of organic material.
  • The soil must be kept moist at all times. 
Soil Preparation.
  • Remove any organic debrit and old mulch from the surface of the soil to be prepared for planting in January.   Apply a 60mm layer of home made compost covered with a 50mm layer of fresh straw mulch.
  • Leave the bed for 4 weeks to build up worm and microbial activity before planting the first crop.
Growing Instructions.
  • Sow turnip seeds In February on the surface of an organic seed growing mix in a mini pot.  Cover the seeds with a light layer of sieved growing mix.
  • Soak the mini pot for 30 minutes in a tray containing 10mm of rainwater.  The water wicks up into the soil without flooding it. 
  • Sink the mini pot up to its rim in the Propagator.  This will keep the mini pot's soil moist until the seedlings are ready to transplant.  Protect the seedlings against frost in the cooler months. 
  • After a few weeks the seedlings are transplanted into jiffy pots containing organic seedling mix and returned to the propagator.
  • Plant them out in February in the prepared bed after making space for them in the mulch.  Without removing them from their jiffy pots, plant them at 150mm centres along rows 150mm apart and water them in generously with dilute seaweed extract.
  • Return the straw mulch, so all the soil is covered, as soon as the turnips are established.
  • A foliar spray of aerated compost tea is applied every 4 weeks with all the other edible plants.
Repeat sowings.
  • Sow more turnip seeds in March, April and May.  At each sowing begin to prepare a new bed for that crop.
  • Turnips should not be grown more than once in the same spot each season.  Follow other members of the crop rotation group instead.
Harvesting and Storage.
  • Turnips can be harvested from May till August, and their leaves can be harvested at the same time as their roots.
Organic Pest Control.
  • Slugs and snails.
    • Turnips 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.
    • If the butterfies get past your defences, spray the crop thoroughly with Bacillus thuringiensis (Dipel in Australia)  This natural soil dwelling bacterium once ingested by the caterpillars produces toxins which paralyse the caterpillar's digestive sytem causing it to stop feeding.  It dies within a few days.
  • Greenhouse whitefly.
    • Aerated compost tea strengthens the plants foliage against whitefly damage.  
    • Exclusion netting is effective against whitefly but they are very small and will occasionally breach your defences, so you will need to check your crop regularly. 
    • Control any infestations by spray your crop thoroughly with an organic horticultural oil (Eco-oil in Australia)
    • Spray again in a few days to ensure second generation whitefly do not survive.
  • Aphids (greenfly).
    • Use the same method as described above for whitefly.
  • Root knot nematodes.
    • A 4 year crop rotation plan is the best cure for root knot nematode.  They do not prosper when their host plant is removed to another bed, and after 4 years, their effectiveness as a plant pathogen is substantially reduced.
General:
  • Regular applications of aerated compost tea boost the natural defences of plants 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.
  • Exclusion netting stops birds digging up worms in your Ecobed, and takes the edge off hot sunshine with a 20% shade factor.