Harvest time is here! As plants mature growth characteristics change. Branches elongate, leaves grow fewer “fingers,” internode length between branches decreases and fertilizer needs change. Plants use more phosphorus and potassium and less nitrogen during flowering. Male plants should have been harvested already. Female calyxes develop small hair-like pistils. Resin production increases.
Some varieties –
Ruderalis crosses, early indicas, Early Skunk, Early Pearl, Early
Durban, etc. – will be ready by the end of September to the first
of next month. The hardest part now is to wait for harvest and not
pick the plants before they are at peak ripeness. Most other
varieties will be ready to harvest in October or November.
Indica varieties are
more prone to disease problems during late maturation than sativa
varieties. The main reason is that indica buds are compact and
dense, which allow little air flow. This environment gives Botrytis
spores a sheltered place to grow. Sativa buds have more air between,
which provides a difficult environment to start growing.
Botrytis (bud mold), rain,
cold temperatures and wind are the main obstacles plants must
overcome for a heavy harvest. Here is how to help your plants
through this difficult time.
Botrytis grows best
on weak damaged foliage in humid (above 50 percent) cool autumn
weather. It is difficult to distinguish at first because it starts
deep within the bud. The grey fuzzy mold and brown rot grows slowly
at first. Once it develops, botrytis spreads rapidly.
If you see botrytis
(see photo) cut it out with scissors that have been dipped in alcohol
to sterilize. Remove 3-5 cm above and below the infected part.
Throw the infected bud away, far from the garden. Do not smoke!
with real nasty sounding names – 1-methyl-cyclohexanecarboxylic acid
(2,3-dichloro-4 hydroxyphenyl)-amide (IUPAC) or
(CAS), from the chemical group Hydroxyanilide, and Dicarboximide as
well as Benzimidazole fungicides are registered in America for
botrytis prevention/control. Botrytis develops resistance to
with sprays of natural Gliocladium roseum and Trichoderma
species. I am also experimenting with a nettle juice that smells
like anaerobic cow manure to prevent botrytis. These natural
substances form a protective coating on foliage that prevents
botrytis from entering the plant system. They appear to work quite
well, but they must be applied before botrytis starts.
the contact (not systemic) Bordeaux mixture (water, copper
sulfate and lime (calcium hydroxide) arrests (stops) botrytis but
cannot be applied near harvest and it can burn foliage if applied in
hot weather or if applied in a high concentration.
Prevent botrytis by
heating and ventilating greenhouses to create a hostile environment
for growth. Often venting in the morning and evening when humidity
If you are growing
in a greenhouse or other enclosed environment, try using evaporated
sulphur. I have seen outstanding results in Switzerland. Look for
sulphur evaporators at greenhouse supply stores.
botrytis by keeping the garden area clean. Remove debris from soil
surface and remove all debris from the garden. A single spore of
botrytis can infect a plant. More than 60,000 spores fit in one
Keep plants healthy
and unscarred. Bud mold starts on bruised and damaged foliage and
stems first. Weak foliage provides a place for botrytis to start and
leaking plant fluids provide a food source. Once started, botrytis
invades healthy plant tissue. Over-fertilization and spray damage
also open the door to botrytis.
Remove weak inner
branches and weak leaves to provide extra air circulation. Reeferman
(www.reeferman.com) from Canada recently explained to me how to
carefully separate the individual buds on a flower top to provide
more air circulation to prevent botrytis. This works very well, but
you have to be careful not to bruise buds.
If you see me at the Hanf
Fair (name correct???) in Berlin this year, please show me you