Good question!
My temps have been a bit lower than usual anyway because of our recent cooler weather. Day time temps have still been in high 70's at canopy level while drooping to mid 60's at night.
Not sure what I'd have to do to bring out dat purple.
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As the irritating Liberty Mutual guy says, I’m glad you asked!
From alchimiaweb.com at
In this post we show you which methods you can use to avoid the cold in an indoor cannabis crop. There are various modes to keep a stable temperature during the winter so you can choose the resolution that best suits to your indoor or greenhouse crop for personal use.
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Taking advantage of the cold in cannabis growing
As already mentioned,
cold temperatures can be highly detrimental to cannabis plants, especially in their early stages of development. In this first period, the seedlings require 20-24ºC to grow properly; however, in the last weeks of flowering things are a little different.
Extra concentration of trichomes
If the plant is flowering in a well-controlled growing environment, the genetics will be able to express themselves fully, blooming without problems and forming beautiful and elegant buds with a high resin concentration.
The natural function of the resin gland is to essentially protect the plant and it's developing seed from extreme conditions like UV rays, cold weather, pests etc, and this way it works to preserve the genetic reproduction (the seeds) and ensure the continuation of the line. Taking this into consideration, it is possible to find a way of taking advantage of cold conditions and, if the timing is right,
harness the low temperatures to increase resin production in the flowers.
Detail view of a leaf with a lot of resin
The cold, being a considerable stress upon the plant, triggers changes in the plant's metabolism which, when they occur in the final stages of flowering, can lead to an increased resin production. If we
gradually lower temperatures to around 16-17ºCduring the last two weeks of bloom, once the buds are fully grown and only need to mature, it's possible to achieve a
much greater and higher quality resin coverage in exchange for only a very slight sacrifice in production weight.
Pearl effect on cannabis plants
The cold and it's effect on flavour and colour
It's also worth mentioning that encouraging lower temperatures during the later stages of flowering will retain a
higher terpene content and can lead to harvesting
more aromatic and flavour-full flowers. Higher temperatures during flowering, drying and curing means that the evaporation and subsequent loss of
terpenes can seriously alter and degrade the organoleptic properties of the buds produced.
Bud with a lot of resin and colored due to low temperatures
For lovers of bright colours another advantage of cold weather in relation to cannabis cultivation is the
wonderful array of autumnal shades that the low temperatures provoke in certain genetics. Many plants will change the colour of their foliage to a beautiful
deep purple, blue or red in cold conditions during the last weeks and when this is combined with the natural 'fade' colours of senescence the display can be truly spectacular and a fitting finale to a successful grow!
Variety showing deep purple leaves
Here we have a couple of examples of the color changes produced in different cannabis genetics, in particular those belonging to the
Blue family of varieties. In these cases the low temperature at the end of flowering has affected the plants, provoking a very
notable color change and an
increased trichome concentration on the buds.
Plant with red leaves
Cannabis plant with yellow leaves
Resuming, it's clear that if properly done, and at the adequate moment, cold temperatures can be used to a positive effect when cultivating cannabis; however, for normal cultivation, during the majority of the plant's life cycle
it is imperative to keep the temperatures within the parameters for healthy growth, between a minimum of 20ºC and a maximum of 26ºC.