How to: Tell when a plant is ready to harvest

25 06 2008

Apart from referring to the given flowering times, one of the best indicators of a female cannabis 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 marijuana 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.

How to: Distinguish between a male and female cannabis plant

24 06 2008

Female cannabis flowers are distinguished by their white hairs, which first appear in pairs at the top of the stem and branches and at the internodes where branches emerge from the stem. These hairs will increase in number, thicken into clusters and change colour from white to orange as flowering progresses.

Difference between Male and Female Cannabis plants

Male cannabis flowers may be recognized by the pairs of tiny pods (initially, smaller than a match-head) in the same locations. They too will quickly increase in number. Soon after forming, these pods will open into mature male flowers which will then distribute pollen.

How to: The difference between the growing and flowering fase

24 06 2008

The number of light-hours a cannabis 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.

Cannabis 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.

How to: Germinate Cannabis Seeds

23 06 2008

How to germinate cannabis seedsWhat is the best way to germinate cannabis seeds?

Basically, you’ll need two saucers or plates and some moist tissue.

– Line the bottom of the first plate with a few layers of wet tissue and drain any excess water from the plate.
– Next, place your seeds on top of the tissue, allowing each seed as much space as possible.
– Place another few layers of moist tissue on top of the seeds, again allowing excess water to drain off.
– Lastly, cover everything with the second plate, upside down, to form a ‘clam-shell’ shape – this will create the dark, moist environment necessary for germination.
– Place the plates somewhere warm (21ºC) and away from direct light.

Your seeds are now on their way to germination.

– Check your seeds every day to ensure that the tissue does not dry out. Spray the tissues with water if necessary.
– Within a few days you should see the first seeds open and a root emerge. It is uncommon, but some seeds may take up to 10 days or even two weeks to open.
– When the first few millimeters of root have emerged from an open seed, you should then CAREFULLY (preferably with tweezers) transfer it to a small container of growing medium (soil or rockwool). Make a hole 2-3mm (max 5mm) deep in the medium, place your seed, root first, into the hole and cover over.
– Your seedling should emerge from the medium within 1 to 3 days.

What are the best conditions for seedlings?

Seedlings will benefit from a bright (though not, initially, under lamps or in direct sunlight), warm (21ºC) and humid environment. A propagator is the easiest way to achieve these conditions. A propagator may be bought or built. It is, basically, a box with a transparent top which allows light in but stops humidity escaping. The simplest form of propagator would be a waterproof box with clear plastic sheeting over the top. The advantage of shop-bought propagators is that they often have built-in heating and/or vents in the cover to allow humidity regulation. They also usually allow more light to reach the seedlings.

Place your propagator next to a window to give the seedlings light, but avoid direct sunlight for the first couple of weeks.

When can seedlings be put under lights / in the sun?

When seedlings have grown their second or third set of serrated leaves (not counting the round cotyledons that initially emerge from the seed) they are usually hardy enough to flourish in direct sunlight or beneath a grow-lamp (preferably metal halide or fluorescent tubes). Always keep your grow-lights at least 50cm from your seedlings.

When can I tell whether they are male or female?

Cannabis will only show its sex once flowering has begun. Cannabis begins to flower when it receives 12 hours of light and 12 hours of uninterrupted darkness in each 24-hour cycle. Once this light cycle (or photoperiod) is initiated, the first flowers should be visible within 2 weeks.

Inside, it is the decision of the grower when to alter the photoperiod and induce flowering. This is achieved by simply adjusting the timers on your lights.

Outside, the grower must wait until the natural daylight hours have decreased to 12 per day. Exactly when this occurs will, of course, vary depending on your locality. In Northern Europe it happens around mid-to-late July.

It is possible to induce flowering outside by allowing your plants 12 hours of daylight each day, then covering them or taking them inside. This must, however, be done every day without fail.

How to: Make Cannabis Clones

23 06 2008

how to clone a cannabis plantThe art of cloning plants could be the most useful of all ‘indoor’ techniques. Cloning allows growers to make the most of every female plant and it’s a skill that anyone can master with a little practice.

Outdoor growers who clone their plants are able to identify gender early in the season and multiply their female plants during the long vegetation period. With low-powered artificial lighting, a promising female can even be preserved for next year’s outdoor crop.

Due to its common association with indoor growing and hydroponics, cloning might appear to be a complex process. In fact, nothing could be further from the truth.

Just as cannabis seedlings will take advantage of the smallest chance to grow, cuttings will quickly make roots and become healthy small plants if a few conditions are met.

Good cuttings are made from strong, green stalks, preferably the growing shoots of the stem and branches.

If possible, cuttings should be 10-20cm long and a few millimetres thick. Avoid stems that are turning woody or hollow, as these are less likely to root. If the aim is to produce a few strong cuttings from each plant, growers should select 12cm sections of the healthiest top shoots. Larger cuttings have more energy and have a better chance of surviving.

If the aim is to make as many clones as possible, any 5-10cm piece of green stem with a growing shoot and a leaf or two can be used. A 30cm branch can be cut at each internode, making 3-6 clones. Tiny cuttings can also turn into clones, though they may take too long to grow to a decent size after rooting. Nevertheless, pieces of stem 3cm long and 1mm thick can root with vigour in bright, humid conditions.

Before planting, treat cuttings with rooting hormone in powder or gel form.

While a good soak in rooting solution is enough to get many clones started, a final treatment with a rooting aid that clings to their stems will increase success rates.

With a razor blade, make a diagonal cut to remove the last millimetres of stem, then dip the cutting in hormone powder/gel. To encourage rooting, many growers gently scrape the lower stems before dipping. A disposable safety razor is a good way to remove a couple of ultra-thin slices from the stalk.

Place treated cuttings in a moist, airy medium that holds them firmly – expanding peat tablets, a 50/50 mix of soil and perlite, cocoa-fibre or rockwool, if available. Clones have no problem rooting in a small rockwool block, then being transferred to soil.

After planting, outdoor clones are given the natural light cycle. Some growers shade rooting clones during the hottest part of the day, while others adopt a ‘survival of the fittest’ attitude. Viable clones will appreciate direct sunlight, and should root quickly.

In hot, dry climates, rooting clones may require a transparent covering to retain humidity. Keep the clones’ medium moist, but not saturated. In good conditions, clones should root in 10-20 days.

Cloning for Sex

The first clone taken from a plant can reveal the parent’s gender with 100% accuracy. It’s easy to reduce the light cycle of cuttings – allow them 12 hours of daylight, then cover them or move them to a dark area. This is much simpler than covering a single branch of a large plant to reveal gender.

When seed-plants reach 30cm, they can yield a cutting or two, which can be given a 12/12 light cycle immediately upon being planted. They will show their gender in 10-14 days, and in many cases they’ll root as well.

It’s fine if these first clones don’t become healthy small plants. Their purpose is to reveal the gender of the parent early in the season, allowing males to be eliminated and all subsequent cuttings to be taken from female plants.

As an added bonus, cloning for sex causes seed-plants to be ‘topped’ early in the season, leaving plenty of time to regenerate a strong double-stem.

Cloning to Multiply

Outdoor growers with plenty of space may clip plants to train them into huge bushes, while balcony growers often cut plants solely to restrict their size.

In both situations, cloning allows extra plants to be made from foliage that is normally discarded.

To keep a balcony plant around 1m by the end of flowering might require quite a lot of pruning. Instead of throwing away over 50% of a female plant during the growing phase, the removed foliage can be made into dozens of copies that plant, all of which will finish under the required height.

Growers who prune plants to make them large and bushy can produce huge numbers of clones. Branches are clipped at regular intervals throughout the vegetative phase to encourage them to split and grow in two directions. As plants increase their size and number of branches, each pruning will yield more cuttings than the last. While this might eventually produce more cuttings than most growers could use, remember that a rooted female clone makes a lovely gift.

Late Cloning

Indoors, cuttings are almost always taken while plants are in the growing stage, as the aim is to preserve a plant in its vegetative state. Outdoors, it is even possible to take clones during the initial weeks of flowering, when the first single flowers begin to show. Cuttings from plants that have begun to flower will often root more quickly than normal clones and should continue blooming at the same rate as the parents.

This means that even in the final, pre-flower trimming (where lower and inner branches with little budding potential are clipped), outdoor growers can clone any viable pieces of stem that are removed from plants.

Every green section of stem with a healthy internode can become a small plant when treated with kindness. Six branches cut from a medium-sized plant in July or August could be turned into 10, 20 or 30 cuttings. Even with a low survival rate of 20%, the result can be a few bonsai flowering plants.

If you’re growing outdoor plants this year and you’ve never made clones, you could try the following experiment just to see how easy it is to produce them, even if you have no particular need to multiply your harvest.

  • Fill a few small pots with moist, airy soil.
  • With sharp scissors, cut a few growing shoots or minor branches from your plants – nothing that you or the plant will miss – just enough to make ten or twelve cuttings of 5-10cm.
  • Give the stems of the cuttings a gentle scrape with the scissors, or your fingernail (some growers use their teeth), and plant a few cuttings firmly in each pot.
  • Leave the pots in the sun and make sure they don’t dry out.
  • In two or three weeks, you should have a few rooted clones as a result of 20 minutes’ work.
  • Any extra care and attention given to future cuttings will greatly improve their survival rate.

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