Garlic harvest!

Tuesday, August 1, 2017

Wrapper leaves snug around cloves.
Garlic harvest is upon us, and if you haven't already started harvesting your garlic, now would be the time to start planning it.  Different varieties will mature at different times, so it's always good to check on bulb development of few bulbs of each variety.  One way to determine harvest-readiness is by looking at the number of green leaves.  Each leaf corresponds to a wrapper leaf around the bulbs.  Wrapper leaves protect the cloves from light, moisture, heat, etc.  For best storability, it is suggested to harvest with five to six green leaves.  That way, if a wrapper leaf or three is lost in harvesting and cleaning, there will still be two to three wrapper leaves around the bulb to protect it from storage rots, desiccation, etc.

Stem and bulb nematode damage
Green leaves should be used as a guideline, but not a rule.  Sometimes on a particularly healthy plant, the leaves can remain green despite harvest-readiness.  Alternatively, if there is heavy thrip damage, high stem and bulb nematode populations, etc. the leaves can brown prematurely.  It is always best to pull a few bulbs and check to see how the cloves are filling the wrapper leaves.  Give the bulb a squeeze, and if there is any give, then the garlic isn't quite ready yet.  You should also cut the bulbs in half perpendicularly to the stem.  Each clove should be tight in the wrapper leaves.  If the wrapper leaves seem a little loose around the cloves, then wait a little longer to harvest.  The cloves in harvest-ready garlic will also start to pull slightly away from the stem, especially in hardneck varieties. 

Cloves starting to pull away from stem.
Hardneck varieties (Allium sativum var. ophioscorodon) produce scapes.  Hardneck types, as a general rule of thumb, produce larger cloves, but have a shorter storage life, which can be greatly influenced by harvest timing.  If you leave harvest for too long, the wrapper leaves will start to decay, and the cloves will continue to grow and pull away from the stem and the bulb will split open, rendering the bulb unmarketable.  Softneck varieties (A. sativum var. sativum) do not produce a scape, and typically have a longer storage life.

Garlic harvested too early might not have fully developed its yield potential or flavour profile, and will tend to shrivel when cured.  Late-harvested garlic is more likely to have poor storability, particularly the hardneck varieties, as the wrapper leaves start to deteriorate, exposing cloves.  It is often better to harvest a little early than a little late.

Target harvest for early in the morning on a dry day for best results.  Do not leave garlic in the sun for long as it can scald, and the cloves will quickly deteriorate.  Handle garlic gently as it is sensitive to bruising.  The higher the moisture or relative humidity when you are drying your garlic, the slower the garlic will dry down and cure, resulting in high disease potential.

Post-harvest handling can dramatically affect garlic quality and storability.  Recent research from Cornell University suggests that root trimming does not have any impact on bulb quality, weight, or disease incidence.  Washing garlic post-harvest, while resulting in good looking bulbs initially, ultimately resulted in more discolouration after drying and curing.  For more details about post-harvest handling of garlic, check out Cornell's Garlic Post-Harvest Study.

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