depends first on when it starts flowering. Second step is identifying as indica dominant or sativia dominant. Indica goes 7-9 weeks sativa goes up to 15 weeks flowering. To judge when a plants ready we go off tric color.
"What the hell does this mean?
When growing Indica hybrids, unless you want to end up on the couch, it’s best to harvest when the trichome heads are fully formed but before they start to cloud over and turn amber. According to the maturation time of the specific strain this could take as little as five days or as long as two weeks. If you allow an Indica to go too long you can dramatically affect the taste and high. Fortunately going too long is not a real problem for most people. I like to study close-up photos taken with a high resolution digital camera; however an inexpensive hand-held microscope works wonders. It almost looks like you are in an alien world when looking at resinated buds using fifty-times-power.
With the Sativa dominant hybrids you want to make sure that all the trichome heads are fully formed and also about thirty percent amber. Letting a plant mature beyond this will risk flavor as well as, the finished smoke may be harsh with very little “high”. There are exceptions as I mentioned; Haze has three different harvest windows all being very late into flower. It is every grower’s job to learn what he or his patients prefer in the terms of “High”.
We have not yet addressed yields because if you are at the third stage of floral maturity with fully form trichomes, then we will have to assume most strains have packed on all their final weight. Even then, there are variables but we can use the guide-lines spelled out below to help gauge the best harvest window for your plants based on the trichomes.
1. Fully formed but still clear will provide a cleaner ‘up’ high with less sedative effect; this is the best window for heavy Indicas.
2. Fully formed and turning slightly cloudy or milky; this is probably the best time to pick most hybrids available today.
3. Fully formed completely cloudy or milky with at least thirty percent of the heads turning amber; this is usually best window for the late maturing Sativa’s such as Haze. This is also a good window when using the plant primarily for Hash production."
http://www.drugs-forum.com/growfaq/1529.htm
http://www.drugs-forum.com/growfaq/12.htm
17.5 Sinsemilla
Sinsemilla ((The word "sinsemilla" comes from the Spanish, and means "without seeds." It is also spelled "sansimilla.")) is any marijuana consisting of seedless female flower buds. Sinsemilla is not a variety of marijuana; it is the seedless condition that results when the female flowers are not fertilised with pollen.
In the United States, most sinsemilla comes in the form of Thai sticks that are imported from Southeast Asia and Japan. Thai sticks are made up of seedless buds wrapped around a sliver of bamboo or a long wooden matchstick. The buds, which may be on one or more stems, are secured with a hemp fibre wound around the stick. A growing amount of fine sinsemilla now comes from domestic sources, such as Hawaii and California. The grass is usually boxed or bagged with pure buds that are manicured (extraneous leaf removed). Infrequently sinsemilla comes from Mexico and, rarely, from Colombia.
Sinsemilla has a reputation as high-potency marijuana, with a sweet taste and mild smoke. It doesn't have the harsh, gagging qualities of the usual Colombian and Mexican grasses. These qualities, however, have nothing to do with sinsemilla as such. The potency of any grass depends primarily on the variety and development of the plant, and the taste and mildness of the smoke depend on the condition of the plant when harvested and the cure. Heavily seeded grass can be as mild and sweet-smoking as sinsemilla when it is properly handled.
When buying grass, remember that sinsemilla indicates a conscientious effort on the grower's part to bring you the best possible product. Sinsemilla is almost pure smoking material with no wasted weight in seeds. An ounce of sinsemilla has about twice as much smoking material as a typical seeded ounce. Also, any marijuana that is fresh, with intact buds, indicated less deterioration of cannabinoids. {Figure 80. Thai Sticks.}
Sinsemilla is becoming a preferred form of grass with homegrowers, many of whom believe that a seedless female is more potent than a seeded one, reasoning that the plant's energy goes to the production of resin rather than seed. There seem to be no scientific studies on this point. Many experienced growers believe the difference is small, perhaps 10 percent.
From observing the resin glands on the bracts, one sees that they continue to develop in size after pollination. Any difference from the unseeded state is not apparent. Whether pollination does in fact hamper or lessen resin production or potency is questionable. but the effect on the plant as a whole can be dramatic. Usually when the female is well-pollinated, growth noticeably slows, and the plant enters the last phase of life, which is seed set. Seed set is a period of incubation, in which the seeds grow and reach their mature state. New growth forms more slowly and lack the vitality of the bloom before pollination. The plant's reaction to pollination is relative. The more thoroughly pollinated the female is, the more pronounced the change in rhythm from vigorous to incubation. A plant on which only a few flowers have been fertilised continues to actively form flowers as sinsemilla.
Not all plants react alike to pollination. When the weather is good and the plant vigorous, even a well-seeded plant may bloom a second or third time before the rate of growth starts a final decline.
To put this in perspective, the main advantage to growing sinsemilla is that the plant remains in a flowering state for a longer period of time. Flowers may rapidly form for four to ten weeks. The flower buds develop larger and more thickly along the stems, yielding more top-quality grass (more buds) than in the seeded condition.
Anyone can grow sinsemilla. Simply remove the male plants before they release pollen. Given a normal spring planting, males usually flowers in August and September, but may being to flower as early as mid-July. Under artificial lights, males sometimes flower after only three months, and before the grower has shortened the photoperiod. Even though the females are not flowering, remove the males from the room before any flowers open. Indoor, the pollen will collect as dust and can fertilise the females weeks later.
Male flowers mature quickly, in about one to two weeks after the immature buds are first visible. Check each plant about twice a week to make sure you harvest all the males before any shed pollen. If you can't visit your garden consistently, then thin the garden, using the preceding section on "Sexing" as a guide. Even though you may not get all the males, the females will be more lightly seeded. Actually, even in carefully watched gardens, the females may have a few seeds. Pollination may come from on occasional male flower on a basically female plant, or a female may reverse and form male flowers. And pollen may come from a neighbour's garden, a problem that is becoming more common. But in practical terms, an occasional seed makes no difference. The female can form thousands of flowers, and when only a few are pollinated, there is little impact on the plant's growth.
20.4 Harvesting Female Buds
The decision of when to harvest females can be simplified by understanding that you want to pick the buds after they have developed fully, but before degradation processes begin to lower potency. There are two criteria you can use to tell when the plants have reached full bloom. The first is recognising the rhythm, with which the plants are blooming. A second is the condition of the flowers as judged by the health of the stigmas and the colour of the resin.
Sinsemilla
Since sinsemilla flowers are not pollinated, the flowering period may last for many weeks. The most common rhythm for sinsemilla is that plants go through a stage of rapid bud formation, and the plants do indeed bloom. This bloom often lasts four to five weeks. The bloom ends when the rate at which new flowers form noticeably declines. At his time you should be able to sense that the bloom is completed. Buds are at their peak potency about one week after flower formation slows. This is the time to harvest. True, the plant may continue to grow slowly, but the main harvest is ready and should be taken.
With sinsemilla, some marijuana varieties have an extended bloom that may last more than two months. With this rhythm, the rate at which the buds form is drawn out, and progresses at a slower but steadier pace. The point at which the bloom is essentially over may not be as obvious as in the first case. Here, use the condition of the buds to make your decision. Stigmas wither first at the base of the buds (older flowers). Those stigmas at the top of the buds (younger) will still be white and healthy, although their tips are often brown. Harvest the plants when about half the stigmas in the buds have withered. The coating of resin glands should still be clear or white, with only a few golden or browned gland heads.
A third type of flowering rhythm is sometimes seen on plants from Thai seed. Flower buds bloom and ripen at different times. These plants also have an extended flowering stage that can last for over two months. You may choose to harvest individual buds, colas, or branches as they ripen.
Seeds
If your primary interest is seeds, the plant should be harvested after the seeds have developed their mature colour. Mature seeds can be seen splitting their sheaths or bracts. When enough seeds have ripened, the plants should be harvested. If the plants are left in the ground and die, many of the seeds will fall from the plant.
For most growers, potency will be of primary interest, seeds only a secondary. With seeded marijuana, flowering is initially rapid until the plant is well-pollinated. If pollination occurs early in flowering, the plants often bloom for another week or two. Generally, you want the plants to flower for at least four weeks before picking, and usually longer, about six to seven weeks.
With seeded marijuana, the bloom is of shorter duration than with sinsemilla. Once growth slows, wait another two to three weeks before harvesting. All the seeds may not be matured, particularly at the top of the bud. But potency of the buds should be about maximum at this time.
some usefull info for you.
i harvest when the trichomes are cloudy/milky and it is a far better smoke/stone in my opinion than waiting untill the trichomes/t.h.c. are degrading(amber trichomes).
sinsemilla is the best buds you can smoke it takes half the product of overharvested/seeded buds to make a joint and is much more potent.
hope this helps.
LUDACRIS.