You can Bud or Flower Marijuana by introducing dark cycles of 11-13 hours that simulate the oncoming winter in the fall as the days grow shorter. As a consequence, it works out well indoors to have two separate areas; one that is used for the initial vegetative state and one that is used for flowering and fruiting. There is no other requirement other than to keep the dark cycle for flowering very dark with no light interruptions, as this can stall flowering by days or weeks. Once a plant is big enough to mature (12" or over), dark periods are required for most plants to flower and bear fruit. This will require putting the lamp on a timer, to create regular and strict dark periods of uninterrupted light. In the greenhouse, the same effect can be created in the Summer (long days) by covering it with a blanket to make longer night periods.
A strict schedule of covering the plants at 8pm and uncovering them at 8am for 2 weeks will start your plants to flowering. After the first 2 weeks, the schedule can be relaxed a little, but it will still be necessary to continue this routine for the plants to completely flower without reverting back to vegetative growth. Outdoors, Spring and Fall, the nights are sufficiently long to induce flowering at all times. Merely bring the plants from indoors to the outside at these times, and the plants will flower naturally.
In late Summer, with Fall approaching, it may be necessary only to force flowering the first two weeks, then the rapidly lengthening nights will do the rest. Give flowering plants high P plant food and keep them on a strict light regimen of 12 hours, with no light, or no more than a full moon during the dark cycle. 13 hours light, 11 dark may increase flower size while still allowing the plant to go into the flowering mode. Use longer dark periods to speed maturity toward the end of the flowering cycle if speed is of the essence. (8-10 days) This will however, reduce total yield. Two shelves can be used, one identical to the other, if strictly indoor gardening is desired.
One shelf's lights are set for 12-13 hours, and one is lit continuously. Plants are started in continuous light, and are moved to the other shelf to flower to maturity after several weeks. This flowering shelf should be bigger than the "starting" or "vegetative" shelf, so that it can accommodate larger plants. Or, some plants can be taken outside if there is not enough space on the flowering shelf for all of them near harvesting. A light tight curtain can be made from black vinyl, or other opaque material, with a reflective material on the other side to reflect light back to the plants. This curtain can be tied with cord when rolled up to work on the garden, and can be velcroed down in place to make sure no light leaks in or out. If the shelf is placed up high, it will not be very noticeable, and will fit in any room.
Visitors will never notice it unless you point it out to them, since it is above eye level, and no light is being emitted from it. Flowering plants like very high P level foods, such as 5-50-17, but 10-20-10 should be adequate. Nutrients should be provided with each watering when first flowering. Trace elements are necessary too; try to find foods that include these, so you don't have to use a separate trace element food too. Home improvement centers sell trace element solutions rich in iron for lawn deficiencies, and these can be adapted for use in cultivating the herb. Prices for these mass produced fertilizers are significantly cheaper than the specialized hydroponic fertilizers sold in indoor gardening shops, and seem to work just fine.
HYDROPONIC FLOWERING SOLUTION, per gallon: 1 tspn high P plant food, such as 15-30-15, or 5-50-17, etc. 1/2 tspn epsom salts 1 tspn Oxygen Plus Plant Food (Optional) 1 tspn Trace Element food I cannot stress enough that during the FLOWERING PHASE, the dark period should not be violated by normal light. It delays flower development due to hormones in the plant that react to light. If you must work on the plants during this time, allow only as much light as a VERY pale moon can provide for less than 5 minutes.
Keep pruning to a minimum during the entire FLOWERING PHASE. A green light can be used to work on the garden during the dark period with no negative reactions from the plants. These are sold as nursery safety lights, but any green bulb should be OK. It is best to keep the dark hours a time when you would normally not wish to visit the garden. Personally, I like my garden lit from 7pm to 7am, since it allows me to visit the garden at night after work and in the morning before work, and all day long, while I'm too busy to worry about it, it lies unlit and undisturbed, flowering away... Flowering plants should not be sprayed often as this will promote mold and rot. Keep humidity levels down indoors when flowering, as this is the most delicate time for the plants in this regard.
Early flowering is noticed 1-2 weeks after turning back the lights to 12 hour days. Look for 2 white hairs emerging from a small bulbous area at every internode. This is the easiest way to verify females early on. You can not tell a male from a female by height, or bushiness. 3-6 weeks after turning back the lights, your plants will be covered with these white pistils emerging from every growtip on the plant. It will literally be covered with them. These are the mature flowers, as they continue to grow and cover the plant. Some plants will do this indefinitely until the lights are turned back yet again. At the point you feel your ready to see the existing flowers become ripe ( you feel the plant has enough flowers), turn the lights back to 8-10 hours. Now the plant will start to ripen quickly, and should be ready to harvest in 2-3 weeks.
The alternative, is to allow the plant to ripen with whatever natural day length is available outside, or keep the plants on a constant 12 hour regimen for the entire flowering process, which may increase yield, but takes longer. Plants can be flowered in the final stages outdoors, even if the days are too long for normal flowering to occur. Once the plant has almost reached peak floral development, it is too far gone to revert quickly to vegetative growth, and final flowering will occur regardless. This will free up precious indoor space sooner, for the next batch of clones to be flowered.
Look for the white hairs to turn red, orange or brown, and the false seed pods ( you did pull the males, right?) to swell with resins. When most of the pistils have turned color (~80%), the flowers are ripe to harvest. Don't touch those buds! Touch only the large fan leaves if you want to inspect the buds, as the THC will come off on your fingers and reduce the overall yield if mishandled.