gibberellic acid feminized seeds

How To Make Feminized Cannabis Seeds Like The Pros

Growing from feminized cannabis seeds is a space and resource-efficient way of getting all girls, all the time. Find out how to create your own feminized cannabis with Royal Queen Seeds.



Growing cannabis is all about resinous flowers, trichomes, and rich cannabinoid profiles. These splendid characteristics can only be found on the female flowers. Having gardens full of robust, un-pollinated sinsemilla females means jars full of mind and body-friendly, crusty nuggets.

The only bummer, unless you grow from clones, is that cannabis is wired to produce about 50% male seeds and 50% females. It is just the nature of the beast.

Wouldn’t it be sweet if it was possible to grow all females from seed, every plant, every time?

Well, that is where the feminizing technique comes into play: two methods of manipulating the cannabis plant to produce only females from seed, every-time. To be truthful, it isn’t every single time. But 99% of the time is a pretty good number, and could be considered entirely male risk-free.

The general practice behind feminization is that female plants are forced to produce pollen, which is in turn used to pollinate other female plants. The outcome? Resulting seeds will be feminized, with no risk of further pollination.


Feminized seeds are super efficient for indoor and outdoor gardeners. Area, time, and resources aren’t being given to plants that will be thrown away two weeks after the 12-12 flip. Similarly, outdoors where a large plant can consume a lot of time and resources in upkeep prior to the autumn show of flowers, feminized plants are also a good way to reduce guerrilla crop pollinating. There’s nothing worse than bush-bashing out to a well-hidden crop only to find a rogue male or two have impregnated every female plant.


“Applications that reduce the ethylene level in tissues or antagonise the action of ethylene causes the formation of male flowers instead of female ones” — Paraphrase, Byers et al., 1972.

There are a number of solutions that can be sprayed on female plants to create male pollen sacs: benzothiadiazole, gibberellic acid, silver thiosulphate, silver nitrate, and colloidal silver.

Colloidal silver is by far the easiest to source or make. It is non-toxic, non-caustic, and can be bought from a pharmacy or easily online. The other solutions can be dangerous, difficult to get a hold of, and expensive—except gibberellic acid, which can be found in nurseries, but is not as effective as colloidal silver. But if you want to watch some freaky plant growth just for the fun of it, give gibberellic acid a try. It is a growth stimulant and makes plants stretch and stretch.


Colloidal silver is a distilled water-based solution in which microscopic particles of silver are suspended. The nature of colloids means the particles will never settle out and can’t be removed by normal filtering. Colloidal silver is available commercially, or you can make your own if you want to totally geek out (see how-to section at the end). It has numerous uses as an alternative medicine. For example, it is used to soothe burns, as an antiseptic and digestion stimulant in people, and as a fungal control in horticulture.

Be sure the strength is at least 15ppm, preferably 30ppm. Less than 15ppm produces male sacs with little viable pollen.

To begin with, select a plant that has the characteristics you want to preserved. Feminizing clones is the usual practice as the growth, flowering, and resin characteristics from the mother are already known. There is no need for any vegetation time once a clone is well-rooted. Simply pot the clone into a small pot, give it a day or two to recover, and begin a 12-12 light cycle right away. A pollen-producing plant only needs to be small as cannabis produces copious amounts of pollen.

Hint: Make two clones once a plant has been selected, one to be feminized and one to be left for pollination. This way, a separate breeding space is created and accidental seeding of other plants, or an accidental sneeze pollinating a whole grow cupboard, is avoided.

Plants can be induced to grow male sex organs as late as four weeks into flowering. Though spraying one week prior to the light changeover is recommended for clones. If a plant grown from seed is being used, wait until the plant has sexed before spraying so you can be sure it is female.

Spray the plants to be feminized with colloidal silver every day, and three times a day if you can manage. Soak them well. Do this for two weeks, then leave the plants to grow as normal. Some growers report getting results after spraying for only 5–10 days.

When sexing begins, male pollen sacs will develop instead of female calyxes and pistils. Male plants mature much faster than females, and viable pollen can be expected within 3–4 weeks once the plant has been sexed. Some growers will spray until the plant shows sexual growth, just to be sure the method has worked. Make sure these plants are well-isolated from any flowering females. A burst pod can release millions of pollen spores, and it only takes one spore per hair to create a seed.


Once the plants have been sprayed with colloidal silver and the pollen is collected, they are write-offs—86 them and don’t smoke them. Giving them a thorough rinse will not work. The colloidal silver is a systemic treatment absorbed into the plant through the foliage and not a topical application. Be safe and bin them.


Sinsemilla is an unnatural state for cannabis. Without human intervention, it would be rare to find an unpollinated female in the wild—unless it was sterile. When sinsemilla plants are left to go beyond their desirable maturation stage by a number of weeks, the plant, through whatever amazing processes evolution has bestowed, knows it has not been pollinated. As a last ditch effort at propagation, it will produce male pollen sacs in an effort to self-pollinate.

This is not the result of genetic or stress-induced hermaphroditism. They are genuine XX chromosome male bananas. With all the genetic information from the female and no Y chromosome, using rodelized pollen creates female-only seeds, although as with colloidal silver, an occasional male may appear.


There are a number of harvesting methods employed to catch pollen.

  • Cover the top of the pot with plastic or card to catch pollen as it falls, or modify a plastic drink cup to shroud the plant and catch falling pollen.
  • Fix a clear plastic bag, perforated at the top for air exchange, around the whole plant.
  • An experienced eye will remove each flower pod prior to it bursting completely open to be sure of catching every spore.
  • Pollinating a female is the easy bit. Depending on how many seeds you want to make, there are a couple of methods that can be used.
  • Using a watercolour or other fine, soft brush or even a cotton bud, dip into your pollen collection and gently apply to the chosen flower. Although thousands of viable spores will be on the end of the brush, enough to pollinate a whole plant, the trichomes on the surface of the pistils will greedily glue everything you offer them. So dip into your pollen stash a few times as you dust.
  • For lots of seeds, put pollen in a bag and put over a whole branch or a whole plant, shake well, and leave for twenty four hours.
  • It is possible to pollinate different branches with different pollens and have a breeder plant that has 1, 2, or 15 different crosses on it.
  • It is also possible to self-pollinate the plant from which the male parts were created. This won’t produce as many seeds as pollinating a separate plant because less female flowers are produced and many are nonviable because of the feminization process.


Treat feminized seeds as you would any other seed from germination to veg, and veg through flower. Observation is where it’s at now, you want the best plants for your garden. Ideally, setting up a separate vegetation/flower space where a number of plants can be grown lets your standard grow space continue with uninterrupted production.

Plants bred using feminization are homozygous. This can have two effects that can’t be assessed until the seeds are grown. Homozygosity will increase the dominant or recessive traits of the parent in the progeny, so features you don’t want and do want can be amplified. Genetics is a weird, weird thing.

Just as with standard male to female crossings (which is a heterozygous process), a number of plants will need to be grown and the best selected for mother plants and future breeding. With enough room, hundreds if not thousands of new plants can be grown in order to select the best of the best phenotypes.


With a bit of aforethought, it is possible to set up an efficient feminization breeding programme—and have female seeds from your favourite phenos on hand all the time. You never know, you might discover the next big thing!


The easiest and relatively inexpensive way—considering how much money is potentially saved by not growing resource and time-consuming males—is to buy a colloidal silver generator, which is the no-fuss plug and play option. Or, make your own, which is quite straightforward and doesn’t require any special skill.

Colloidal silver is formed by passing a current from a pure silver electrode through distilled water. This simple electrolysis is all there is to it. Although distilled water does not conduct electricity very well due to its lack of mineral content, enough is passed through to create micro silver particles and silver ionisation. Sounds technical, but it really isn’t.

Feminized cannabis seeds only produce female plants, which has a number of advantages. Find out how to do it with Royal Queen Seeds.

How Can I Feminize My Cannabis Seeds?

You may have heard of feminized seeds before, either online or from another grower. This progressive type of seed has become possible thanks to feminization – a fairly new technique for cannabis growers that rose to prominence during the 1990s. Usually, feminized seeds are those that have undergone a chemical process to make them always germinate into female plants. If you’re curious about how to feminize marijuana seeds yourself and are interested in learning more about the process, be sure to check out the following guide.

Why Should I Feminize My Seeds?

Feminized seeds will always sprout into female plants. That’s important, because female plants are the only type of cannabis that will grow buds and create THC. Male plants, in contrast, will pollinate any female plants in their immediate vicinity. Once that happens, the female plant will stop producing THC. As a result, male plants have the potential to ruin an entire garden. Don’t let that happen. Instead, make sure all of your plants are female before they germinate!

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How Does Feminization Work?

The key to feminization lies in a compound called ethylene. It’s a hormone that has several roles in a plant’s life. Notably, ethylene levels determine the sex of a plant. By either reducing the level of ethylene in plant tissues or inhibiting the action of ethylene, you can trick a female plant into turning hermaphrodite and developing pollen – typically a male-only trait. Then, you can use that female pollen to breed with another female plant. The seeds produced by this kind of pairing will be feminized.

How To Make Feminized Seeds With Colloidal Silver

Using colloidal silver is one of the simplest and most reliable ways of making feminized cannabis seeds. It’s also readily available online and at local pharmacies.

Equipment You’ll Need

Making feminized seeds with colloidal silver requires some specialized gear. Necessary equipment includes a power adapter (9-12 volts), electrical wire, distilled water, 99% pure silver, alligator clips, a PPM meter, and some gloves and goggles for safety. You can find pure silver in spools of silver wire or some coins.

The Process

Using colloidal silver for feminizing cannabis plants is essentially a four-step process. After you make the solution, you’ll spray it on a plant, use that plant’s pollen to breed feminized seeds, then collect them.

Make A Colloidal Silver Solution

Set your power adapter to 9-12 volts. Strip both ends of the electrical wire with pliers, scissors or another sharp tool. Affix the alligator clips to one end of each wire (soldering works well for this). Next, connect the wires to the power adapter. Then, attach a piece of silver into the jaw of the alligator clip – but don’t let them touch each other. Fill a glass jar with some of the water and put one clip on opposite sides of the glass. Plug in your adapter and wait 20 minutes. Now, check the PPM of your solution. You want your solution to have a ratio of between 15 and 30 PPM.

Spray Your Plants

Three days prior to switching to a 12/12 light schedule, start spraying your plant with the colloidal silver mixture at least once per day (but preferably three times per day) until you see it begin to develop male pollen sacs. Don’t be shy – make sure you get them nice and wet. You should begin to see changes forming in your plants between five and ten days after you begin spraying. Once you begin to see male pollen sacs, they should fully develop in three or four weeks.

Pollinate The Plants

Next, you’ll need to collect the pollen once it fully develops. Cover the top of your pot with something to collect the pollen. Then, using a watercolor brush or piece of cotton, gently brush the pollen spores over a female plant. Do this to a female plant that’s about two or three weeks into the flower cycle. You can pollinate a single branch of a plant, or even an entire female plant for maximum seeds.

Collect Feminized Seeds

Wait about six weeks to harvest your feminized seeds. You’ll notice the calyxes beneath the buds will be swollen. Seeds will start bursting out of them. Now you can collect your feminized seeds. Once you do so, you don’t need to wait before planting them – they’ll be ready to go immediately!

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How To Feminize Seeds With Gibberellic Acid

If you’re interested in how to make feminized seeds without using colloidal silver, gibberellic acid offers an alternative. This is a plant hormone you can use for sexing cannabis seeds in a similar process to colloidal silver.

Equipment You’ll Need

To create a feminized seed spray with gibberellic acid, you’ll need even less equipment than you do with colloidal silver. First, you’ll need gibberellic acid. You can find this relatively cheaply online for about $15. You’ll also need a PPM meter, a glass container and water. Of course, never forget about safety – gloves and goggles are still essential.

The Process

To make feminized seeds using gibberellic acid, you’ll need to make a solution, spray it on your plants, pollinate another plant and collect the seeds.

How To Make A Gibberellic Acid Solution

Add the gibberellic acid into water and mix it thoroughly until your solution reaches about 100 PPM. Use your PPM meter to keep an eye on the concentration of your solution. If you add too much acid, you can dilute it with water. Once your solution is ready, pour it into a spray bottle to prepare for the next step.

Start Spraying Your Plants

Once your gibberellic acid solution is ready, spray it over one branch of a female cannabis plant. You’ll need to do this daily for a week or more right after you flip your plant from veg into flower. One side-effect of using this technique is that your plant may experience noticeable stretching. If this happens, don’t be surprised. Keep spraying your plant until you see it start to form pollen sacs.

Pollinate The Plants

Once your plant starts to develop male sexual organs, collect the pollen using the same techniques as when applying colloidal silver. Then, using a paintbrush or similar tool, cover the branch of another plant with the pollen. Again, you’ll want to pollenate a female plant that’s two or three weeks into its flower cycle.

Collect Feminized Seeds

Once your pollinated plant begins to develop seeds from its calyx, you can collect them. These seeds will be feminized and ready to plant. If you’re interested in learning about how to feminize weed seeds, this is one of the safest, easiest and most effective ways of doing so.

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How To Feminize Cannabis Seeds Using Rodelization

Colloidal silver and gibberellic acid are both scientific ways to get feminized seeds. However, if you’re wondering how to sex marijuana seeds without chemicals, rodelization is a natural, albeit unreliable way to do it.

Equipment You’ll Need

This is the most natural way to make feminized seeds. As a result, you basically just need the plants themselves.

The Process: How To Produce Feminized Seeds Using Rodelization

Once a female plant gets too old without being pollinated, as a result of experiencing stress, it will try to do so itself as a last-ditch attempt to protect its genetic line. By inducing stress on a female flowering plant, you can therefore make it develop its own male pollen sacs.

Make Plants Flower

Once your plant is mature enough to flower, switch it from vegetation to flowering by changing your number of light hours from 18 to 12. Then, your plant will start producing buds. Let your plant flower for another seven or eight weeks, making sure to take good care of it the entire time. You don’t want to stress it out too early – if you do, it will just herm instead of growing pollen sacs.

Induce Stress

After your plant’s normal flower cycle is over, let it continue to mature for another few weeks – that’s when it gets stressful for cannabis. There’s no guarantee that rodelization will work, but if it does, you’ll start to see male flowers developing on your plants. These will look like little bulbs – different from the fluffy buds of healthy female cannabis plants. Once these begin to develop, keep waiting and taking care of the plant.

Collect Feminized Seeds

If you’re lucky, after a few more weeks, your plant will pollenate itself. As a result, the seeds that the plant develops will be feminized. This method usually results in fewer seeds than other feminization techniques.

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Remember – Safety First!

While it might sound like a fun science experiment to feminize weed seeds, remember how dangerous working with chemicals can be. Whenever you’re working with chemicals like colloidal silver and gibberellic acid, safety is your number one priority. Make sure you use gloves and goggles whenever you’re handling these chemicals. In addition, never smoke a plant if you’ve sprayed it with either of these compounds. It might be tempting, but you absolutely don’t want to inhale the chemicals!

Ready, Set, Feminize

Together we learned how feminized seeds are made, and, as you can see, there’s no need to be intimidated about how to make female seeds yourself. Now that you finally know how to get feminized seeds from marijuana plants, you can try these techniques out in your own garden. Follow our simple instructions, and you’ll be able to germinate 100% female plants from every seed of your own!

Usually, you can easily buy feminized seeds, but some seedbanks produce regular seeds only or you just don't have feminized seeds right now. If you’re curious about the chemical process that makes seeds always germinate into female plants, here are 3 effective ways to do that.