Growing Marijuana - Flowering stage, harvesting & curing

A complete guide to everything you wanted to know about growing marijuana in the UK, but were just too stoned to ask.

By Sensi Sid

Growing Marijuana - an introduction
Location, heating & ventilation
Lighting Systems & Techniques
Germination & Vegetative Stage

The flowering stage
When the day length decreases to about 12 or 13 hours per day, flowering will start. For outdoor and greenhouse plants, this usually starts some time in September but can be earlier in some modern hybrid strains. For indoor plants this is whenever the grower adjusts the lamp timers. Indoor growers using fluorescent tubes may want to swap their cool white tubes for warm white at this point.

Flowering is induced when the level of a particular hormone reaches a critical point. This hormone is produced during the dark period (night) and destroyed by light during the day. It is important, therefore, to ensure that the dark period is totally uninterrupted by any light , even a few minutes could disturb this sensitive process.

Imature Female flowers

After a week or two of short days, look out for the immature flowers where the leaves join the stems. Males look like little green, upside down clubs (the playing card type) about one or two millimeters across and females look like green, slightly hairy hemp seeds with one or two thick, white hairs protruding from the top.

Pull up and throw away the males (or use them for making hash oil) before the flowers open and pollinate the females. The idea is to produce female flowering tops with no seeds and false seed pods oozing THC-containing resins; this is called sinsemillia which means "no seeds". If you are using fertiliser, change to one that is low in nitrogen and high in phosphorous.

The flowering tops will continue to grow, in the hope of receiving pollen, for another 4 to 8 weeks and produce more resins as they get older. When the plants are mature then they are harvested.

Harvesting and curing
Growers often disagree about the timing of the harvest and most have come to the conclusion that it is largely a matter of taste. When the plants are actively flowering, the resins contain a higher proportion of THC than during the vegetative stage. During the later

Imature Male flowers

stages, when flower production has slowed, THC is degrading to other related chemicals such as CBD. It is thought that THC is mainly responsible for the "high" and CBD for the more physical, "stony" sensations such as lethargy. If you want a clear high then harvest when approximately 35% of the pistils (little white hairs) have turned red or brown. If, on the other hand, you prefer the heavier hit you get from something like pakki-black resin then wait until 65% of the pistils have changed colour.

Cut off the flowering stalks with scissors and hang them upside down in a cool, dry, dark place until they are dry enough for the central stem to snap when bent; this may take one or two weeks. Pack the dried buds loosely into zip top bags or airtight jars and store in a cool dark place (the fridge is fine for this). Do not crush the buds any more than you have to as the trichomes holding the little beads of resin will fracture resulting in earlier degradation of the THC. Similarly, do not store the buds in a freezer as this also causes trichome fracture. Flowering tops stored like this can remain fresh for many months.

In an emergency, fresh buds can be dried more quickly by hanging them over a radiator or by spreading them out on a baking tray and putting them in an oven which has been pre-heated to gas mark 1 and then turned off. Naturally dried buds have a much better flavour and are less harsh to smoke than quick dried ones, so try to be patient if possible!

A batch of seeds is unlikely to produce all female plants; even if it does, each individual plant is likely to differ slightly. Cloning can produce many identical plants from one mother with ideal characteristics. Ideally, the process needs to be done under artificial light, indoors.

First, decide on which female to clone. If it has just finished flowering, switch the lights to a 18 hour on/6 hour off cycle; this will usually persuade the plant to revert to a vegetative growth state.

Prepare enough 3" pots filled with a moist 50/50 mixture of commercial seed and cutting compost and horticultural grit. Water them with a copper fungicide solution until the compost is damp, not sodden. Poke a pencil-diameter hole, about 4cm deep, in the middle of each compost filled pot.

Select healthy shoots about 10cm long, remove most of the bigger leaves, and then cut off the whole shoot with a scalpel or razor blade. Immediately drop the cuttings into a bowl of cool water so that the cut ends don't dry out. When all the cuttings have been taken, remove the bottom 1cm from the first cutting, with a scalpel, while it is still under the surface of the water. Remove it from the bowl and immediately dip the end into hormone rooting powder (or solution). Now, place it in the hole in the compost and lightly press the surrounding compost such that the stem of the cutting is held snugly in place, trying to avoid rubbing off the rooting hormone. Repeat this process with the other cuttings.

Put the pots in a propagator or a polythene covered, waterproof box. Put the propagator under artificial light set to a 18 on/6 off cycle. The idea is to maintain a fairly high humidity around the cuttings so that they do not lose too much water through their leaves while they are still growing roots. If the grow room is hot, it may be necessary to increase the ventilation in the propagator or box to avoid fungal growth. The cuttings will not need watering very often as most of the evaporating water is trapped in the propagator.

After a few weeks you should see some new growth at the tip of the cuttings. At this stage, gradually increase the ventilation in the propagator over a period of a few days so the cuttings acclimatise to the lower humidity of the grow room. When a healthy root system has developed, transplant the cuttings to their final growing positions for the vegetative stage.

Sea of Green
Sea of Green is a method developed by indoor growers to increase the frequency of harvests. The basic principle is to grow a larger number of small plants for a shorter length of time than the traditional method.

The growing area is arranged as a series of two or more shelves. Using a two shelf system as an example, the upper shelf is equipped with fluorescent tubes. This is used to grow a number of clones, vegetatively on a 18/6 daylight cycle, until they are big enough to flower. At this point they are transferred to the lower shelf which can be equipped with either HPS or fluorescent light. The lower shelf is operated on a 12/12 daylight cycle and forces the plants into flowering.

Mature Female Bud

The shelves should be shielded from light spill from the adjacent shelf, either by light proof curtains or doors. Each shelf should have it's own timer, of course.

Clones of a single variety should be grown such that the growth rate is the same for each plant. By experiment, it is possible to determine the shortest length of time the plants have to be grown vegetatively before flowering is initiated. The yield from each plant will be comparatively low but the yield per month from the available growing space should be higher that with other methods.

Variations on this theme include a three shelf system where shelf one is used for rooting cuttings, shelf two for vegetative growth and shelf three for flowering.

Bugs and diseases
Keep an eye out for bugs which may attack your plants. If you use an insecticide, be sure to use one based on natural active ingredients, such as pyrethrins; after all, you will be smoking it sooner or later - don't poison yourself.

Aphids can be washed off with a soft-soap solution - cover the plant pot with a polythene bag, tied loosely around the stem, to avoid too much soap getting in to the compost. Whitefly can be controlled by spraying with permethrin at three day intervals until eradicated.

Spider mites can be a real problem when growing indoors. They like hot, dry conditions so try and keep the humidity level up to discourage them. Unfortunately, fungi and moulds like high humidity so, like most things in life, a compromise has to be reached.

Botrytis (Grey Mould) likes humid conditions. Cut off and destroy any infected parts; reduce the humidity by increasing the ventilation and, if necessary, spray with a fungicide which is safe for use on vegetables (read the packet).

Avoid using chemicals whenever possible, especially if you are nearing harvest time. Some insecticides and fungicides are highly toxic, in contrast to THC, and may cause you serious damage. Large scale growers use parasitic insects to control pests but this is probably impractical for the cupboard grower.

Much of the information contained on this website would be illegal were it to be practiced in most countries around the world - including the UK. Our intent is to educate and inform NOT to encourage anyone to break the law.

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