Growing Marijuana - an introduction
Location, heating & ventilation
Lighting Systems & Techniques
Flowering stage, harvesting & curing
All plants start, originally, from seed. Choose a variety that is advertised to grow in the conditions that you have planned. Good seeds will be firm to the touch and not 'pop' when squeezed between thumb and forefinger. Avoid those which look undersize or very pale in colour.
Some books advise soaking the seeds between sheets of blotting paper and then transferring to a growing medium when they have sprouted; this is not strictly necessary, just poke the seeds, individually, into small plant pots containing a commercially produced seed compost to a depth of about 1cm. Water the compost, until it is damp - not sodden, with a solution of traditional copper fungicide or Cheshunt Compound. Place in a warm (15C to 25C), light place out of direct sunlight, keep moist and they should show their first true set of leaves within three weeks. At this stage, transfer the seedlings with as much of the seed compost as possible to individual containers, being careful to handle them by the leaves (not the stem) and avoid as much root damage as possible.
If you use small, biodegradable peat pots for sowing then the entire pot can be planted into the bigger container. Some growers transplant several times using progressively bigger pots but I find it better to transplant to the final growing container as soon as possible. Anyone not familiar with germination techniques should practice on bird seed or fish bait hemp before attempting to grow their very expensive 'Sensi' seeds!
SKD don't actually agree with the germination section above. We would strongly advocate the pre-germination
technique. Using distilled water (boil some water it and let it cool), place a few layers of tissue
of kitchen roll on a saucer, pour some of you distilled water on to it, place the seed/s on to
it, and cover with more wet tissue/kitchen roll.
Then take another saucer, and place over the top to keep it dark, then seal the whole setup into a freezer bag or similar. Place all this into an airing cupboard or somewhere warm. The freezer bag should keep the paper moist, but don't let it dry out.
Check every 12 hours or so, but within 1 -3 days, you'll see the seed/s begin to split, and what looks like a small beansprout will appear at the seed base, this is the root. Here again some people argue that the seed should be planted immediately, however, we prefer to wait until the "beansprout" is about 5mm long.
Once the root is 5mm, place the seed/s into a small potting container. Poke a small hole about 10mm deep (a chopstick is great for this), and place the seed in it - beansprout downwards - this is the root after all! Be careful to handle the seed by the pod not the new root growth.
It is also important to reduce your handling of the seed as much as possible, when replanting from the potting container, it should be planted into the final growing container.
The vegetative stage
Most varieties need to be grown for about 40 days minimum before they are mature enough to produce flowers. Of course, you can grow them for longer and produce much bigger plants but this is not always convenient. Smaller plants are more easily hidden or disguised. A four metre monster will look rather obvious between the rows of tomatoes!
During the vegetative stage, the plants need to get as much light as possible for as long as possible. This precludes starting your outdoor crop in September. Mid, to late May is usually a good time to plant out your seedlings.
Choose a growing site which faces south (for maximum sunlight) and is not overlooked by nosy neighbours. Plants can be disguised by growing between other tall plants such as runner beans or tomatoes.
Prepare the soil in your growing patch by digging in a bucket full of garden compost or well-rotted farm manure per planting position a few weeks before planting out. If the soil is sticky clay then dig in some horticultural grit to prevent the soil becoming waterlogged.
Seedlings that have been sprouted indoors require a period of 'hardening off' before planting outside. This involves gradually acclimatising them to outdoor conditions over a period of several weeks. Start by leaving them outside in a sheltered, sunny spot during the day and bringing them in again at night. Gradually increase the time they are outdoors until they are outside 24 hours a day. Without hardening off, the plants will suffer shock and their growth will be temporarily retarded.
Plant out with a space of at least a metre between each plant and water in well. There should be no need for extra fertiliser until the plant reaches at least a metre in height. In some areas, rabbits and deer can be a nuisance; the only answer is to build a fence to keep them out.
Some varieties of cannabis can grow to 4 metres in height; if this is a problem they may need to be pruned or trained. Pinch out the growing tip when the plant has produced 4 sets of true leaves; this will make the plant branch into two main stems. Pinching the growing tips again will further increase branching. Be careful not to overdo this process as the plants are stressed by pruning and their development may slow down unacceptably or they may even exhibit hermaphrodism. Upper branches can be bent horizontal (carefully!) and tied to canes with garden twine. This encourages budding at the leaf nodes and reduces the overall height of the plant.
During the summer, the plants will need watering occasionally. Don't keep them waterlogged; allow the soil to dry out somewhat between waterings. If the soil has not been prepared with plenty of compost or manure, then apply a garden flower fertiliser such as Miracle Gro according to the directions on the packet. It is better to under-fertilise than to over-fertilise; if growth seems satisfactory, either use no fertiliser or quarter strength fertiliser.
Greenhouse growing is a significant improvement on outdoor methods. Plants will grow more rapidly under glass and the buds will suffer no wind or rain damage. The flowering period can be extended because of the few degrees of frost protection.
Unless your plant variety is known to be short and bushy, don't start too early or the plants will be pushing the roof off by September. Decent sized plants can be grown from a June sowing.
It is possible to use the soil in a greenhouse border but this may contain pests and diseases. A much better option is to use commercially produced potting compost in containers. Use a general purpose soilless compost like 'Levingtons' and add about 30% grit, perlite or vermiculite to improve aeration and drainage. Perlite and vermiculite are better for aeration but are light in weight, some added grit will make the pots heavier and less likely to fall over. 12" pots seem about right for most plants but you can use bigger ones if you have the space.
Large plants will transpire large amounts of water when the weather is warm and sunny, so be sure to water regularly. Be careful not to over water; let the top few inches of compost dry out before watering again. In some areas, the tap water has high levels of calcium carbonate dissolved in it (hard water) and this can lock up nutrients in the compost. Use rainwater collected from the greenhouse guttering where possible. If you spend weekends away, it may be wise to invest in an automatic watering system. Ventilate the greenhouse in hot weather to keep the temperature and humidity down; high humidity can promote the growth of fungal infections. Buy an automatic roof vent opener (£15 to £20) and, if you can afford it, a louvred pane and automatic opener (£50 to £60).
Soilless composts have enough nutrient added for several weeks growth but you will need to feed with Miracle Gro or similar when this is exhausted. Organic growers can add blood, fish and bone mixture to the compost or water with fish emulsion. Use caution with fertiliser and don't over feed. Dilute to half or quarter strength to be safe.
In open ground, the wind thickens the plant's stem by bending it back and forth. In the greenhouse the plants may grow less substantial stems so tie the main stem to a cane with garden twine to stop it falling over. You can also train the main stem(s) by tying them to a horizontal cane; this will induce budding along the stem's length.
Automatic mains timers should be used to switch the lamps on and off. Some indoor growers keep the lights on for 24 hours per day although 18 hours should be sufficient and may produce sturdier plants (and result in a smaller electricity bill!). Make sure that the dark period is truly dark; just a few minutes of light interrupting the plants' "night" may induce hermaphrodism.
Plant your seedlings in suitable containers such as 10" or 12" diameter flower pots. Square section pots will waste less floor space than round ones. If you use old food or detergent containers then make sure that they have drainage holes in the base and that they are opaque. Follow the advice for compost, watering and feeding from the greenhouse section.
Main stems will tend to grow spindly under artificial light; tie them loosely to canes to stop them falling over. The lower stems will grow weakly if they are too far from the light source; pinch them out if they look too spindly, they may be used for cuttings. Grow the plants on until they are about two-thirds the intended final height before inducing flowering.
Growing media and feeding
In the opinion of the author (and of the Dutch seed suppliers, Positronics) cannabis grown organically has a superior taste and texture than that grown hydroponically (i.e. without soil). Organically grown plants seem also to be less susceptible to pests and diseases.
The choice of soil based (e.g. John Innes ) or soilless (e.g. Levingtons) compost is largely a matter of taste. Soilless composts are probably easier to carry, mix and handle than soil based.
Whatever your choice of compost, at this stage the pH should be neutral (around 7); this can be tested either by using a pH probe available from any good garden centre or by using litmus paper.
The texture of soilless composts will probably need to be altered because, straight out of the bag, they tend to get too waterlogged. It is important for the roots of the plant to get oxygen and for this reason about 30% to 40% horticultural grit, perlite or vermiculite should be added to open up the texture of the compost. Never use builders sand or anything you brought back from a seaside holiday as it will be either too salty or too alkaline. Perlite is a light, puffed volcanic glass and it is potentially dangerous to breathe the dust particles given off while handling it; therefore you must thoroughly wet it before mixing it. Vermiculite is an expanded mica in granular form; it presents the same risk as perlite so take the same precautions.
Plants need to feed as well as breathe. Growing plants need an adequate supply of nitrogen, phosphates and potash together with small amounts of the trace elements Mn, Fe, Mg, Cu, Zn, Mo, S and B. Nitrogen is necessary for healthy leaf growth, phosphates for healthy roots and stems and potash for producing flowers.
Commercial potting composts have enough nutrients added by the manufacturer for several weeks growth. This can be supplemented by adding pelleted chicken manure, composted cow manure or blood, fish and bonemeal when the compost is first mixed. Follow the instructions on the packet and, if in doubt, use less rather than more. If you are not fussy about following strict organic method, a soluble, chemical plant food can be used instead; this is added to the water in the proportions stated on the packaging.
The percentage of nitrogen, phosphate and potash is stated on the packet. A 15-30-15 mix means that there is 15% nitrogen, 30% phosphate and 15% potash with the rest being an inert filler.
At the vegetative stage, a fertilizer high in nitrogen is required. When the plants start flowering, change to a formula higher in phosphate and potash. Trace elements are included in most commercial formulas or can be added separately by using a chemical mix or a seaweed extract. At the risk of boring the reader I say again, more damage is caused by overfeeding than underfeeding.
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Copyright © 2002 SKD