What are preflowers?

Preflowers, as opposed to full blown flowers, generally appear after the fourth week of vegetative growth from seed. Check carefully above the fourth node. Please note that preflowers are very small and and almost impossible to differentiate without magnification. A photographer's 10x loupe is handy indeed when examining preflowers.

As the images below demonstrate, the female preflower is pear shaped and produces a pair of pistils. Frequently, the female preflowers do not show pistils until well after the preflowers have emerged. Thus, don't yank a plant because it has no pistils. Pistillate preflowers are located at the node between the stipule and emerging branch.

Also, some female preflowers never produce pistils. A female preflower without pistils is difficult to distinguish from a male preflower. Thus, hermaphodite issues should not be resolved by the appearance of preflowers, without pistils, on a plant otherwise believed to be a female.

The male preflower may be described as a "ball on a stick." However, its most recognizable feature is its absence of pistils. Sometimes, a male plant will develop mature staminate flowers after prolonged periods of vegetative growth. These appear in clusters around the nodes.

The following image shows a male plant in early flowering. Staminate flowers are located at the node between the stipule and emerging branch.

How can I identify a female by seeing its pre-flowers?

These pictures and quotes were donated from a sexing thread about identifying females by their pre-flowers (primordia) which was authored by "Crazy Composer". The pictures alone speak a thousand words...

Note: The plant parts marked with an "X" are called "stipules", they appear on both male and female plants.

This diagram shows the difference (on a slightly more mature plant) between genuine pre-flowers and actual bud sites, which are - in fact different animals altogether.

From a further distance, but quite clear-cut.
I know how it is for some of the newer growers who are eagerly anticipating their first view of an actual marijuana flower. Well, this is what it looks like, play your cards right and you'll have thousands of these hairs clumped tightly together and covered in crystals that will smell so nice. Don't worry, it's coming.

Flower Biology

As you can see in the pic, this cola is composed of several sub-units that are will fill out before reaching maturity. In this phase, the plant has finished the stretching phase and is developing bud sites.

Depending on the strain, bud development may start in the middle of its flowering period.

Every single sub-unit is itself a cluster of single female flowers. New Flowers are formed throughout the flowering period. You can see new flower production on top of each sub unit.

In this pic, you can see (above the yellow lines) where the single sub-units develop new single flowers. You can recognize them because the new pistils in formation have tiny stigmas.

Let's see a single flower!
This pic is a pre-flower but is alright for our purposes. It explains how a single female flower formation occurs.

This single flower is called a pistil and the two hairs coming out of it are called stigmas. Male pollen reaches the stigmas and make their way to the female egg cell which is located inside the pistil. This pollination process will produce the seed. Growers tend to prefer seed-less (non-pollinated) sensimilla!

Resin is produced on female flowers and on the leaves near them. It is produced by a particular structure called a glandular trichome.

In this pic you can see on the leaf that resin is produced in some kind of ball over a thin neck. if you have a magnifying glass, you can look in the ball and see color changes (from transparent to white to gold/brown) and determine when resin production and THC % has peaked. Rough handling of buds will break the trichomes off.

Young pistil.
Let's see now how a pistil evolves during the flowering period. Above the yellow line you can see a young pistil. It is thin and has white hairs.

Stipule
Here is a pic of an older pistil. The body has enlarged. The stigmas are still looking for some pollen. The small leaf under the pistil is called a stipule (Stipules are more evident with pre-flowers.)

This is probably two or three days later, as you can see hairs are becoming (starting from the top) brown/red. Probably at this stage it can still receive male pollen.

In this pic I've underlined three pistils that are as mature as the one in the previous pic (more or less). Other stigmas have dried up, probably due to rain and wind. In these conditions some stigmas lose their vitality and start to dry and to become brown/red. This is not a sign of ripening, just a normal event

On the left of this pic, you can see two pistils fully mature. The stigmas are totally colored and dried. The body of the pistil is now fat and is beginning to lose its turgidity. On the right you can see a cluster with pistils in various stages.

The pistil after a couple of days. It has lost its turgidity and probably is not receptive to pollen. it is dying. When all 70/80 % of all the pistils of a bud are at this stage, resin production has slowed if not stopped.

Gradual ripening.
The maturation of the pistils in a bud is not synchronized but gradual. As you can see in this pic, you have lots of pistils at different stages of development. See the dimension of the bodies. At harvest, you will probably see lots of brown hairs, but also some white at the top of each single sub-unit where the new formed pistils are.

When stigmas are dried and pistil is dying , the hairs will easily break and fall down.

Last modified: 05:19 - Feb 02, 2005

How can I determine the sex of seed plants with clones?

As compared to the observation of preflowers, forcing clones is an almost foolproof method of determining sex. This method anticipates that the grower has started a batch of plants from seed. After several weeks of vegetative growth, the plants should have branched enough that cuttings may be taken. The cuttings should have at least one node and be at least an inch and a half long.

1. The seed plants are numbered or otherwise made distinguishable from each other.

2. Take 2 cuttings from each seed plant. Each of these are given the same number as their donor plant.

3. Root these cuttings and pot separately.

4. One representative clone of each plant is placed in a separate light proof flowering area and the photoperiod there is changed to 12/12. Please note that since these clones will be discarded after they show sex, that practically any light source will serve our purposes here.

5. The other clones remain in vegetative growth. By the time the flowering clones show sex, the now-identified as female vegetative clones are sexually mature and ready to flower themselves.

6. For larger crops, retain both the donor plant and the non-flowering clone for vegetative growth. Both may be used as mother plants to provide clones for harvest oriented flowering.

After 10 days flowering what does a male look like?

The following image displays a male plant at about 10 days flowering.

How do I sex using a paper bag?

Get a small paper bag or something similar that is lightproof (a paper bag will not be suitable for strong H.I.D lighting), and a plastic coated twist tie.

Select a plant that you would like to sex and choose a growing tip. Take the paper bag, place it over the top of the selected tip and seal with the twisty tie. Then, to simulate the flowering phase, simply remove the bag after the 12hr dark period, and replace when the 12hr day cycle ends.

After 7-14 days, the growth-tip you covered should start showing signs of its sex.

"There is plenty of air inside the paper baggage because it would hold its own blown up shape...sorta balloned over the branch tip."

This is for people that dont have room for clones or just want to know the sex of there plant without takeing and rooting early cuttings.

• 1 can of black spray piant
• 1 box of plastic ziplock baggie (sandwich bag size)

Take the plastic baggie and spraypaint the outside of the baggie, then find one of the lower branches that is furthest from the light (this will insure that light reflection on the black paint isnt too intence for heat buildup)and just simply slip the baggie over the branch for 12 hours of darkness.

If you have painted the whole baggie, then no light will get through to the branch when the lights are on. You will see sex on that one branch in 7 to 10 days in most cases.

I have done this many times on inside and outside plants.

Should I force flower my plants to determine sex, then revert them to complete vegetative growth once the sex is known?

No, forcing flowering to determine sex, then reverting to vegetative growth stresses the plant, delays the eventual harvest and causes the plant to stretch unnecessarily.

The better course is to either flower numbered clones or to observe preflowers in vegetative growth.

What does an emerging MALE preflower look like?

Identifying a true preflower is way to tell sex before 12/12. That way you can take clones from the known females without wasting the time and space on males.

Note:
(Kifit) "do not try to sex a seedling based on the very first preflower you see with a 25x times microscope.....wait and make sure. The time between using a 25x to spot the very first preflower sex and the plant dropping pollen is at least 10+ days away and so it's safe."

"It's best to cull a male only after you are 101% sure - when you see 2 or 3 (or more) immature male flowers bunched together on the internodes or the top growing tip - this is a male, for sure, females preflowers have white " spears " that appear in a vee. ..but "every now and then a sexually indistinguishable flower appears" (Ed Rosenthal)

After a few weeks in veg, plants will begin to show their sex. Usually the males show first. The male preflower is a miniscule ball. It appears that there is a small piece of foliage that covers the ball and protrudes outward when the male preflowers first appear.

The following pics show MALE preflowers the FIRST day they show their future pollen distribution centers.

Many times preflowers will appear at the fourth or fifth node, whereas the plant is on the 7th or 8th node. These preflowers usually don't develop into full flowers, but are only an indicator of the plants sex.

Female on left, male on right. Im only certain about the sex cause I watched them several more days. 25X magnification.

After 10 days flowering, what does a female look like?

The following image clearly displays a female plant at about 10 days flowering, using a 400w HPS. NOTE: Indica dominant strains will flower faster than Sativa varieties.