Harvest and postharvest
Maturity
Indications of garlic maturity are:
- The stems have not fallen down, but leaves have started to die back and are still slightly green.
- Bulbs are of good size.
- Cloves are seen easily from outside the bulb.
- In cross-section, the skin between the cloves becomes thin and well-developed rather than fleshy.
- Internal clove colour is creamy rather than white.
- The neck softens above the bulb.
- Bulbs develop in the neck or on top of hard-necked varieties.
Do not allow bulbs to over-mature in the field, as too many skins will be discarded and bulbs will discolour, open up and become sunburnt or rot.
Pull the bulbs by hand. Harvesting with an onion machine can cause excessive bruising. Some harvesting is now done with a modified carrot harvester. Undercutting with a back blade to ease pulling and reduce labour is most common.
If the plants are uniformly mature and well-cured, they can be topped and tailed at harvest. However if they are still green, most of the stem will need to be retained to allow the cloves to mature as the plant dries. Topping and tailing too early without sufficient curing can promote storage rots.
If the plants are to be lifted whole, place them top over tails (to prevent sunburn) in rows in the sun for up to two weeks if no rain is imminent. This produces white shiny bulbs, allows deeper stacking of plants on pallets in sheds and aids cleaning.
If it is necessary to store bulbs immediately after harvest while the plants are green, care must be taken not to stack them too deeply and cause rotting.
Just before marketing, top and tail with secateurs or knives. Clean the bulbs of all loose scales and roots and grade them for size. Cleaning aids include brushes to remove loose scales.
Continuous handling of garlic may cause skin dermatitis in some people.
Storage
If kept dry and well ventilated, garlic will keep well as whole bulbs at ambient temperatures for two to five months. They may shrink if kept too long.
Long-term storage at 0 to 1°C, at a relative humidity lower than 60 per cent will keep garlic in good condition for up to five months. It can rot if the relative humidity is too high and bulbs can sprout above 5°C.
Eriophyid mites can be a problem in storage, especially if the relative humidity is too high. These mites cause brown sunken spots on the cloves.
Marketing
Market garlic in 10kg cartons. Well-presented, large garlic attracts the best prices. Supplies from all sources are fairly evenly balanced throughout the year.
Grading will maximise returns. Voluntary grading standards for bulb diameter in Australia are: medium 35 to 45mm; large 45 to 55mm; extra large 55 to 65mm; jumbo 65 to 75mm; and super colossal, more than 75mm.
Organic garlic
There is potential to increase supplies of organic garlic for the domestic market and to develop export markets in Asia. The best prices are obtained for organic produce. However, this may have lower yields and smaller bulbs than conventionally-grown garlic.
Organic garlic is grown without synthetic fertilisers and pesticides and is best grown under the directions of an organic certifying organisation such as the National Association for Sustainable Agriculture, Australia or the Biological Farmers of Australia.
Garlic shoots
Some garlic is marketed on the domestic market from May to September as ‘fresh garlic shoots’ or ‘garlic leek’, of which the edible part is the stem. This should be 10 to 20cm long, with no sign of bulb swelling. Italian Pink is a good variety for this purpose. The Giant Russian or elephant garlic may also be used to supply ‘garlic leeks’ on the domestic market. Garlic shoots are washed, trimmed, cleaned and graded. They are used as a garnish, in stir-fries and soups.
Storage in oil
Storing garlic in oil is not recommended because of the risk of botulism. Botulism is a potentially fatal food poisoning caused by a toxin produced by the bacteria Clostridium botulinum in the absence of oxygen. Commercial preparations of garlic in oil contain acidifying agents that prevent the growth of the Clostridium bacteria. Freezing or pickling in vinegar is a safer alternative for preserving garlic in the home.
Acknowledgement
This information is based on a DAFWA Farmnote prepared by John Burt.
Further information
AGIA (Australian Garlic Industry Association)
Email: info@garlicaustralia.asn.au
Web: www.garlicaustralia.asn.au
Perth Markets Ltd (PML), Market City website for production and prices at www.perthmarket.com.au