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GARLIC GROWING GUIDE
The ten stages of growing garlic
Harvesting garlic is all about timing. Harvest too early and the bulbs will not be fully developed and will lack flavour, harvest too late and the bulb wrappers will lack layers and the garlic will not keep. It is a tricky task to pick the right time, but a little knowledge makes this task much simpler.
When to Harvest
When to Harvest
Climate and Garlic Type
Garlic is generally harvested in NZ between November and February. When to harvest garlic depends on the type of garlic, the climate zone, sunlight hours, and any local micro-climate conditions. Seasonal variations can made a huge difference - one particular garlic group can vary up to three weeks between years depending on the weather conditions prior to harvest.
The first step in knowing when to harvest is to determine your climate zone and the type of garlic you are going to grow by following our charts below.
As a general rule, there is an order in which garlic groups are ready to be harvested. The turban garlic group is normally the first to be harvested followed closely by the asiatic type. Then artichoke then creole and purple garlics. Next is the remaining hardneck garlics of porcelain, rocambole and the purple stripe groups. Finally it is the turn of the silverskins.
There is about 2-3 week harvesting gap between the early, mid and late harvesting garlics irrespective of the climate zone. Some hardneck garlics are ready when the scape finishes coiling and begins to straighten up. To further refine when garlic is ready to be harvested is the second step of counting the remaining green leaves left on the plant as the leaves brown off.
The stem of plants are elongated in colder conditions and the leaves are a little narrower. The false stem is a good indicator of bulb size. As a general rule by measuring the first leaf near the ground if a stalk is 10mm it should have a 40-60mm bulb, 20mm stalk should have a 60-80m bulb and a 30mm stem should have a 80-100mm bulb.
Remaining Green Leaves
One of the best ways to determine when a garlic bulb is mature is by counting the number of green leaves remaining on the plant. Once the maximum number of leaves is obtained (10-12 depending on the climate zone), the plant puts its energy into bulbing for between 8-10 weeks. As the bulb grows the lower leaves die off. The last week before harvest the cloves tend to get their colour.
Each leaf represents one outer skin on the bulb, if garlic is left too late in the soil there might not be any leaves to protect the cloves during curing and storing. Thus do not wait until all the leaves are browned off. It takes about a week for each leaf to brown off so it is easy to determine the likely harvest week. There are two indicators for counting leaves; one for softneck and the other for hardneck garlic.
Softneck garlic (silverskin & artichoke) is harvested when 6-7 green leaves (we go with 6 fully green leaves) remain on the plant. This will ensure that the bulbs have three bulb skin layers to protect the cloves from drying out during storage.
Hardneck garlic is harvested when 4-5 green leaves (we go with 4 fully green leaves) remain on the plant. This will ensure the bulbs have at least three bulb skin layers after cleaning the bulbs to protect the cloves from drying out during storage.
There is a good reason behind the difference in harvesting based on green leaves between softneck and hardneck garlic. Softneck garlic have three internal leaves that wrap around the internal bulb between cloves, while hardnecks has one internal leaf for this purpose. These internal leaves also become the final top leaves but do not wrap around the outside of the bulb. Thus it is necessary to have more green leaves on the softneck at harvest in order to get the same amount of wrappers protecting the outside the bulb in curing and storage.
Pre-harvest Bulb Inspection
If you are unsure as to whether a bulb is ready for harvest it is possible to gently inspect the bulb. Dig beside bulbs without affecting the roots of a few representative plants.
Taking care not to touch the bulb or significantly affect the roots and using only your gloved hand gently remove the topsoil near the bulb.
Bulbs should be plump but still should have a few bulb wrappers surrounding the bulb. The diagram above illustrates the different stages of bulb development. If the bulb wrapper (skin) is perished and the cloves are starting to appear the harvest is too late.
How to Harvest
How to Harvest
Harvest during fine weather. A grower can delay the harvest if needed, but not to the point which will affect the protective bulb wrapper around the cloves. Wet plants and soils encourage mould and decay and it is more challenging to practically remove and clean the crop before curing.
If harvesting in mild-winter areas where the clove was planted shallow and is in light soils then the bulb should pull out easily without digging.
In heavy soil or if the cloves were planted deeper for colder-winter areas then it is necessary to insert a garden fork or trowel. Use the tool to dig down into the soil under the bulb to loosen and carefully lift up the bulb taking care not to mark it. Do not put too much pressure on the false stem (pseudostem), particularly with the softneck and semi-bolting garlics like turbans, asiatics and creoles, as the bulb may separate from the neck.
Once out of the soil hold the bulb in one hand and use your other hand to gently rub the roots to dislodge as much soil as possible. Do not use water as this is likely to encourage disease and drying will take longer. During this process look for defects, disease and any unusual development in the neck, bulb or roots.
Whatever approach you take, ensure you take care of the bulb and prevent bruising by not banging or damaging them before transporting them to be dried. Likewise, keep the bulbs out of direct sunlight as it can damage the bulb wrapper. Remarkably, sun damage can occcur after less than an hour's exposure ito direct sunlight.
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