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Basic Cultivation Instructions

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    Posted: 27 May 2005 at 12:00

What are the advantages of growing indoors?

- Indoor cultivation allows the grower control over all the factors governing plant growth - light, water, nutrient, heat, humidity, airflow and so on. When these factors are effectively managed the usual result is a more potent crop achieved in a shorter space of time than would be possible with outdoor growing.

- Similarly, indoor cultivation allows the grower to decide exactly when to induce flowering, giving more control over the speed and size of the crop.

- Grow-lights allow plants to enjoy the benefits of direct, intense light for their entire 'daytime' life. This is not possible when growing with sunlight. More direct light generally results in denser, more resinous buds and a more compact plant.

- The resin that coats the flowers of indoor plants need not be affected by environmental factors such as wind and rain - which can damage the glands

- Indoors, there is a smaller range of pests that may prey on or damage plants. However, the sealed environment of a grow-room also removes the possibility of naturally occurring beneficial insects (which prey on pests) and, unchecked, may result in a far more serious infestation than is likely outdoors.

- Indoor cultivation allows the grower to work simultaneously with plants at different stages of growth. This can be achieved by having two or more growing areas, typically one on a 12/12 photoperiod for flowering, the other on 18/6 for vegetative growth. This set-up allows a 'rolling' or perpetual harvest (where a number of plants are put into and harvested from the flowering area every week or fortnight)

- Perhaps most importantly, having a two-cycle growing area allows the possibility of keeping 'mother-plants' and making clones. Cloning enables a grower to retain the individual genetics of one favourite plant for years, if desired. Keeping a female plant in a perpetual 18/6 photoperiod allows it to continue vegetating indefinitely. Any shoots cut from this mother plant can then be rooted and transferred to the flowering area. This means the grower is able to flower many exact copies of the mother while retaining the 'master copy' in the vegetative area.

Indoors, what are the advantages of growing in soil?

- The difference here is similar to the difference between indoor and outdoor cultivation. Soil growing requires less equipment, investment and, generally, less work to control the various factors influencing growth.

- The only specialist equipment required for the simplest indoor soil set-up would be seeds, organic nutrients, a light and a timer. The remaining equipment - soil, pots, fans, reflective materials and such should be easily available in most countries.

- As an organic compound, soil is less sensitive to changes and small variations than a synthetic medium like rockwool. It could be called a self-regulating environment. Thus, pH testing equipment is usually not required.

- Similarly, organic nutrients are gentler to plants than the concentrated salts and minerals of hydroponic feed mixtures. Therefore, while it is still possible to over-fertilise an organic system, such a mistake is less likely to 'burn' or kill plants. An EC meter is not required for soil growing

- In short, soil growing is easier and more forgiving of growers' mistakes. Therefore it is a highly advisable method for the first time indoor grower.

Indoors, what are the advantages of growing hydroponically?

- Indoor cultivation allows more control over a plant's life cycle than outdoor. In the same way, hydroponic cultivation allows the grower an even greater level of control.

- Since plants in a hydroponic setup are growing in a synthetic, neutral medium the grower is able to dictate exactly which nutrients are given to a plant, and at what levels. Of course, this requires more care than organics and usually necessitates the use of a pH meter (to measure acidity in water) and an EC meter (to measure the level of nutrient in water by means of its Electrical Conductivity).

- Hydroponic growing mediums are less bulky and heavy than soil, often easier to handle and possibly easier to dispose of. Pests and fungus are less likely to flourish in rockwool or similar mediums, and are almost never endemic to newly bought synthetic mediums.

- Hydroponic nutrients, since they are highly concentrated, take up less space than organics, especially for large crops. They are usually pre-mixed and do not require the grower to supplement them or combine several different formulas. Also, they will often smell less than organic nutrients.

- In short, the more in-depth control available with hydroponics, when managed effectively, allows for a bigger, more potent and sometimes even faster crop. While such systems are not recommended for first-time indoor growers, those who have experienced success with soil cultivation indoors may wish to try this as the next step in refining their technique.

What are the advantages of growing outdoors?

- Outdoor cultivation requires less equipment, expertise and labour.
For the first few weeks of life, outdoor plants need the same care and attention as indoor ones. However, once a few basics have been well established, outdoor plants may be left (in a good, sunny spot) to take care of themselves. They may need to be regularly watered and fed and, occasionally, pruned but most of their development will be accomplished simply by allowing them to grow over spring and summer.

- This feature of outdoor cultivation is what makes 'guerilla growing' possible. Established plants may be placed outside in remote or wild areas and left to their own devices throughout the growing season. The guerilla grower need only visit them a few times in this period, or even just the once, at harvest time.

- Outdoor plants will usually yield more than indoor ones. This is simply because they are able to grow larger. Few indoor setups are able accommodate plants larger than 180cm. Assuming that detection is not a problem, outdoor plants may comfortably grow to 2 or 3m in height. It is possible for a single plant of this size to produce 500g or more of dried bud.
Germinating seeds early in the growing season (March or April in the Northern hemisphere) will allow your plants a long vegetative period before flowering is triggered by the shorter days of late summer.

- Sun, air, wind and rain are free!

- Some people prefer the taste and effect of organically grown cannabis. Many cannabis lovers insist they can easily differentiate between buds grown with soil and sun and those produced with hydroponics and grow-lights. This, however may simply be the result of their smoking over-fertilised indoor cannabis, or even the fact that indoor buds can taste very different, due to their containing an uncommonly high level of THC that is simply not attainable outdoors.

I have a growing area of X m³, how many plants can I fit in here?

There is no single correct answer to this, no matter how big or small the area in question. There are many other variables to consider, most importantly the intended size of the finished plants and the type of lighting used.

The height of the ceiling in a grow-room probably affects the potential number of plants more than the floor-area. The height of the ceiling dictates the maximum height at which grow-lights may be suspended. Bearing in mind that lamps should never be closer than 50cm (80cm for 600w lamps) to the tops of plants, it is possible to work out the maximum height to which a plant may be grown in a particular area. Large plants obviously need more floor space than small ones.

For example, a growing area with a ceiling height of 3m (10ft) and a floor area of 3m x 3m could accommodate plants nearly 2m tall(probably the maximum practical height for indoor growing). Such plants would each require at least 1m² of floor space. So, assuming the grow-lights in this room were sufficiently powerful (two 600w or better) to penetrate the foliage and illuminate the lower sections of large plants, this area could comfortably accommodate 6 such plants (and a maximum of 8).

The same area, with smaller plants (around 1m) and the lights hanging lower could hold 50 or more individuals, as each would require only about .4m² of floor space. Such a garden could also be illuminated with three or four 400w lamps, as the light does not need to penetrate so far downwards.

It is down to the individual grower which of these two set-ups would produce a larger harvest, though the odds are for greater success with more, smaller plants.


What is the difference between the growing and flowering phases?

The number of light-hours a plant receives in each 24-hour cycle is the chief determinant of whether that plant is in its growing or flowering phase.
Plants that receive 18 hours or more of light in each 24-hour cycle are in their growing or vegetative phase and in nearly all cases will remain in this state until the number of light-hours drops. They gain height quite rapidly. Vegetating plants will often display pre-sexing spurs at their internodes, but will very rarely show their gender. Their foliage is generally a lighter green than that of flowering plants. How long vegetation continues depends on the grower, the growing area, the variety being grown or the natural light cycle. There is no set length of time for the vegetative period.

Plants that receive 12 hours of light and 12 hours of UNINTERRUPTED darkness per 24-hour cycle for a period of two weeks or more will enter their flowering phase. Flowering Indica varieties will slow their upward growth in favour of producing female or male flowers. Sativa varieties will often continue their upward growth while producing flowers. Flowering plants (especially Indicas) often turn a darker green as they mature. The flowering period for each variety of cannabis is a set length of time, usually between 6 and 12 weeks.

What is the light-cycle for growing?

Sensi Seeds recommends a vegetative photoperiod of 18 hours light, 6 hours darkness in each 24 hour cycle. Some literature advises that lights should be left on 24 hours per day for the vegetative cycle, but we have observed no growth advantage from using this photoperiod. It burns 25% more electricity and does not allow vegetating plants their natural dark period (where they switch to consuming oxygen instead of the CO2 used during the 'day').

Which is the best light to use in the growing phase?

Ideally, cannabis should be given light in the blue/white spectrum during its vegetative period. The best source of such a spectrum is a Metal Halide (or mercury vapour) High Intensity Discharge Lamp .
Next in effectiveness are fluorescent lights (3 or more 1m long 'cool white' tubes).
Growers who wish to use only one light for growing and flowering should consider a 400W High Pressure Sodium ballast running a 400w SON-T-PIA- AGRO bulb . The SON-T sodium lamps are usually intended for flowering, but the AGRO version has an increased blue/white spectrum that allows it to be used for vegetation as well.

What sort of nutrients should I use in the growing phase?

Vegetating plants need a full range of nutrients - nitrogen, phosphorous and potassium (N, P and K), plus various trace elements. Vegetating plants will benefit from proportionally higher levels of nitrogen.
Sensi Seeds recommends Fish Emulsion for growing on soil.
Sensi Grow (a 2 component feed) can supply all the nutrient needs of vegetating plants in hydroponic systems.
Sensi Boost can benefit the root systems of plants in both soil and hydroponic mediums. Healthy roots lead to better vegetative and flowering growth.

How long should the growing phase continue?

The length of time to vegetate a plant is the choice of the grower.
As a rule of thumb, Indicas should be vegetated to about half their intended final height before flowering is induced.
Sativas need far less time in the growing phase to achieve the same final height as an Indica, as they can continue to gain height all through the flowering phase. It depends on how much Sativa influence a particular plant has, but most Sativas should be vegetated to a third or less of their intended final height.

What is the shortest possible growing phase?

The mostly-Sativa varieties, such as Jack Herer® ), Northern Lights #5 x Haze® , Mother's Finest® and Silver Haze® may be put into flowering while still seedlings - as soon as they are sturdy enough to be exposed to grow-lights (when they have grown their third set of serrated leaves). In the case of clones, these varieties may be put into flower as soon as the cuttings have rooted.


What is the light-cycle for flowering?

The optimum light cycle to induce and continue flowering is 12 hours of light, 12 hours of darkness in each 24-hour cycle. Slight variations on this cycle may be possible, but 12/12 is considered ideal because this photoperiod will induce flowering in all varieties of cannabis, while still allowing 50% of each day for the plants to photosynthesize and grow.

What is the best light to use in the flowering phase?

Ideally, cannabis should be given light in the red/orange spectrum during its flowering phase. The most efficient producers of light in this spectrum are High Pressure Sodium (HPS) High Intensity Discharge lamps .
While fluorescents may be sufficient for maintaining healthy vegetative growth, there is no really effective substitute for a HID lighting during the flowering phase. While it is possible to flower with fluorescents, the amount and intensity of light that reaches the plants during flowering will directly affect the weight and density of the buds they produce. Therefore, an HPS HID lamp will more than pay for itself within a crop or two.
During flowering, larger grow-rooms often employ one MH lamp for every two or three HPS lamps in order to give plants a more complete light spectrum. The same effect can be achieved in small grow-areas with the use of a single SON-T-AGRO HPS bulb (only available in 400w). The AGRO bulb produces high levels of red/orange light, but also has 30% more blue/white light than a normal HPS.

Is there a light I can use for both growing and flowering?

Growers who wish to use only one light for growing and flowering should consider a 400W High Pressure Sodium ballast running a 400W SON-T-PIA-AGRO bulb . The SON-T sodium lamps are usually intended for flowering, but the AGRO version has an increased blue/white spectrum that allows it to be used for vegetation as well.

How early can I begin flowering? Are there strains that can flower as soon as seedlings/clones have taken root?

Cannabis may be flowered at any time in its life, even as a newly emerged seedling. Indica varieties, however, need to vegetate for at least a few weeks if they are to reach a worthwhile height by the end of flowering. Indicas should be vegetated to about half their intended final height.
The mostly-Sativa varieties, such as Jack Herer® , Northern Lights #5 x Haze® , Mother's Finest® and Silver Haze® may be put into flowering while still seedlings - as soon as they are sturdy enough to be exposed to grow-lights (when they have grown their third set of serrated leaves). In the case of clones, these varieties may be put into flower as soon as the cuttings have rooted.
These strains will continue to gain height all through their flowering phase. For example, it is not unusual for a NL#5 x Haze cutting to be flowered at a height of 15cm, and still reach a final height of 1m.

What sort of nutrients should I use in the flowering phase?

Flowering plants need the full range of N-P-K plus trace elements, though they will need more phosphorous and potassium than in the vegetative phase.
For soil growers, Sensi Seeds recommends Seaweed Concentrate® as a soil conditioner. Added every two weeks, it will ensure that soil retains sufficient primary and trace elements for healthy flowering.
Sensi Aarde Bloem® is a bud-booster for soil growers. It is intended for every day use.
Sensi Flower® (a 2 component feed) can supply all the nutrient needs of flowering plants in hydroponic systems.
Although the root-systems of flowering plants tend not to increase in size as rapidly as in the vegetative phase, they may still benefit from Sensi Boost® . Healthy roots are vital to plant development and treating them can help maintain their health even once growth has slowed or stopped.

How tall will my plants grow in the flowering phase?

Indicas can generally be expected to gain 50 - 100% of their vegetative height during flowering.
Sativas can increase their vegetative height by 200 - 300% or even more during flowering.

Will plants always finish in the time-period given for flowering?

The flowering times are given as a guide, and are based on the finishing time of a healthy, properly looked-after plant. They are as accurate as possible but a multitude of factors can affect a plant's flowering time.

Why are my plants taking longer to finish?

In general, it is stress during a plant's life that negatively affects its flowering time. Stress, of course is a very general term, covering any unfavourable growing conditions. Some of the most common causes of stress in indoor plants are:
Insufficient lighting
Light pollution (plants receiving light during their 'night' period)
Incorrect pH
Lack of airflow

How can I tell when a plant is ready to harvest?

Apart from referring to the given flowering times, one of the best indicators of a female plant's ripeness is the colour of the hairs covering its flowers.
These hairs start out white, darkening to orange or red as the plant matures. A plant is generally at its ripest when about 75% of the hairs on its flowers have changed colour.
Observed with a high-powered magnifying glass, the resin glands on a ripening flower will undergo the same colour change, darkening from clear to opaque then usually to yellow, amber or orange. As this happens, THC is turning into the more soporific of cannabis' active ingredients, CBD.
Some growers choose to harvest their plants when about 50% or fewer of the hairs have turned orange, reasoning that while the overall amount of resin produced will be less, a higher proportion of it will be THC.
Be patient, is our advice.

Is there any advantage to stressing plants before harvest?

This is a matter of opinion. Ours is to respect plants and we strongly disapprove of any stressing, in any way. Some growers find that deliberately stressing plants a few days before harvest seems to increase the amount of resin on a plant.
It is probably best if growers who are interested in this theory test it on two near-identical plants (preferably clones from the same mother). Stress one of the plants in any number of ways - denying light, water or nutrient are the most common - and leave the other to finish normally. Then compare the dried produce of each plant to see if this theory works for your circumstances.


How do I harvest my plant?

A mature plant should simply be cut at the base of its stem and hung upside down. The largest fan-leaves should be removed immediately, but it may be best to remove the smaller leaves once the plant is drier. This can be done at about a week after harvest. Allowing the rest of the leaves to remain may offer some protection to the still-wet resin glands. Also, trying to remove smaller leaves immediately upon harvest may cause the flowers to be damaged.

Should I flush the growing medium with plain water before harvest?

If a plant is given the correct amount of nutrient throughout its life, flushing should not be necessary, even in hydroponic systems.
The plants on display in The Hash Marihuana & Hemp Museum tend to receive nutrient-water right up until the day prior to harvest, with no discernable negative effects.
In practice, however, it is possible even for experienced growers to marginally over-fertilise their plants, resulting in a less favourable taste. If you are concerned that you may have over-fertilised, it won't hurt to flush your plants' growing medium for, say, two of the three days prior to harvest. It is better not flush on the actual day of harvest, as doing so will allow the plants to take up extra water and therefore extend the drying period.
Flushing for one or even two weeks before harvest is unnecessary, unless the grower is also experimenting with the theory of stressing plants before harvest.

Is it possible to remove only the flowers and "regenerate" a plant?

Cannabis is an annual plant. Once flowering is underway, a plant is nearing the end of its life.
It is possible for a plant at the end of its flowering period to be kicked back into vegetative growth by returning it to an 18/6 photoperiod. However, this can take a long time, sometimes longer than to vegetate a new seedling to the same size.
In terms of time, effort and power, it is usually more efficient to start again with new seeds or clones.
Regeneration is worthwhile when trying to preserve the last example of favourite plant for future propagation.

How do I dry the plant?

Your plants should be hung upside down in a cool, well-ventilated area, away from direct light. The drying area should not be too small, as the plants will be releasing a lot of water into the atmosphere. Confined conditions during drying can lead to fungus in the buds.
They will usually take between one and two weeks to dry sufficiently for long-term storage, though the smaller buds may be dry enough to smoke in less than a week.
NEVER attempt to speed up the drying process by adding heat or light. This will serve only to reduce a plant's overall potency.

How do I "cure" the flowers for long-term storage?

Buds should be allowed to dry completely before storage. A completely dry bud may still be slightly sticky, but will crumble easily between the fingers. The stem of a dry plant will snap rather than bend.
Once this dryness has been achieved, the buds should be placed loosely (not packed) into a glass jar. The jars commonly used for preserving fruit - with a rubber seal and locking closed with a wire lever - are the best type for curing buds.
Seal the jar and store it in a cool, dark place. After a few months your buds will be cured. They should have a drier crust on the surface, but will release their freshly-dried aroma when this layer is broken.

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