Pre-Flowering

Marijuana Grow Basics by Jorge Cervantes

Marijuana is a dioecious plant, being either male or female. however, intersex (aka hermaphrodite or bisexual) plants with both male and female flowers can also occur.

Pre-flowers are the first sign of a plant’s sex. The pre-flowers grow at branch internodes just behind the leaf spur or stipule about the fourth week of vegetative growth, when the plant is six to eight weeks old. This is the point of sexual maturity, the first sign a plant is preparing for flowering – the next stage in life.

You can see pre-flowers with the naked eye, but a 10x to 30x magnifier will make viewing easier. You can accurately determine plant sex after eight weeks. Using this method, you can distinguish sex before inducing flowering.

Plants grown from seed under an 18/6 day/night photoperiod will generally show pre-flowers before plants that are given a 24/0 day/night photoperiod. Once pre-flowers are distinguishable as male or female, plants can be induced to flower with a 12/12 day/night photoperiod.

Male Pre-Flowering

Male pre-flowers are normally visible when plants are six to eight weeks old, after the fourth week of vegetative growth. The pre-flowers emerge behind the stipule at the fourth to fifth branch internodes and generally do not turn into full flowers.

Early male flowers are easy to spot with the naked eye. They are located at branch internodes. Male pollen sacks hang like little balls. Each pollen sac has enough pollen to pollinate all the females in the average grow room.
,br>Remove and destroy male plants grown from seed as sn as you can verify male pre-flowers. Removing male plants now ill virtually ensure an all-female crop sinsemilla.

Female Pre-Flowering

Female calyx formation initiates about the fourth week of vegetative grwth when they developed female pre-flowers. The appearance of pre-flowers does not respond upon photoperiod. It occurs when a plant is old enough to show signs of sexual maturity, about six to eight weeks from seed germination. The pre-flowers emerge behind the stipule at the fourth to fifth branch internodes.

A pre-flower looks like a regular female flower; most have a pair of white fuzzy pistils. Pistils normally emerge after the light green seed bract part of the pre-flower has formed. Wait until pistil have formed t ensure the plant is female and not male. The pre-flowering stage lasts from one to two weeks.

Plants grown from seed under an 18/16 day/night photoperiod will usually shw pronounced pre-flowers before plants given a 24/0 day/night photoperiod. And, under a 16/8 day/night regimen pre-flowers show more quickly and are often more pronounced. Once pre-flowers are distinguishable as female, plants can be induced to flower with a 12/12 day/night photoperiod.

Always wait to induce flowering until after pre-flowers appear. Inducing flowering with 12 hours of uninterrupted darkness and 12 hours of light before pre-flowers develop will stress the plant. This stress could cause odd growth, and plants might grow into hermaphrdites. Inducing flowering before pre-flowers form will not speed flowering. Flowering will occur about the same time as if you had waited for pre-flowers to show!

Vegetative seedlings are now ready to start flowering. Male and female flowers will form and are easy t see.

1 comment to Pre-Flowering

  • rellarachi

    hey anybody out there knows about lighting mistakes? I was in the hospital for two and a half days and my fiancé put my plants on a 12/12 for reasons beyond me. my plant is in week two pre flower> can go back on 16/8

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