I have an indoor growroom and in my recent harvest I found seeds in the buds, but I’m sure there are no male plants in the room. I’ve heard that light leakage can cause plants to become hermaphrodites. Is this true, and if so, do you have any tips for avoiding this?
Cannabis plants are monecious. This means they have the ability to be either male or female. Or in the case of hermaphroditism, they can be both. The reason to make sure there are no males or hermaphrodites in your garden is because male flowers make pollen. When pollen touches the white hairs on a flower, it makes a seed, and seeded weed gives you headaches. Even though there are reasons in nature hermaphroditism could be important, such as continuing the species in case there is no male present, hermaphroditism is generally a bad thing when talking about cannabis plants.
Light poisoning is the most common cause for a normal plant to hermaphrodite.
Light poisoning refers to the flowering night cycle of a plant being unnaturally interrupted with light. The best way to prevent this is to close yourself inside your darkened room during the daylight, and then after allowing a few minutes for your eyes to adjust to the dark, check for any light leaks from covered windows, door jams, etc. Also cover all timer and appliance lights with tape.
Negative stressors can combine with small interruptions of the light cycle to cause hermaphroditism, especially with less-stable, clone-only hybridized strains. When the night cycle is abnormally interrupted, it sends a mixed hormonal signal to the plant. This can cause a full female plant to throw some male flowers. Male flowers are easy to identify, especially when side by side with female flowers. Male flowers look like small bunches of bananas, which will take a week or two to swell before they burst and release their pollen.
Finding a hermaphrodite in your growroom can happen at any stage of the flowering cycle and is indicated by the presence of male flowers growing on the same plant as female flowers. As with all species in nature this can occur in varying degrees. A plant can become slightly or majorly hermaphroditic. In cases where singular male flowers are found between the branch and stalk nodes, you should be diligently removing them as they grow. You must re-inspect the plant top to bottom every few days to be sure pollination and seeding doesn’t occur. If you find male flowers (anthers) actually growing from within the female flowers (buds) the situation is a little more dire. You can still remove all the male anatomy as it appears, but it will be harder to find and much more prevalent. This is a horrible discovery that leads to a tough decision: Should you let the plant live and risk the whole crop being ruined by seeds?
In either case, once hermaphroditism has compromised the safety and purity of your sensimilla, the plant should not be propagated further. Remember, once a hermy, always a hermy. The plant pictured here is in the tenth and what should have been the final week of ripening, but a timer failed and one light stayed on continuously for almost two weeks, causing this vegetative regrowth. Because the light was continuous, the plant made no pollen. This method of re-vegging can be used to save a flowering plant you have no copies of, but be careful, as this may cause some strains to hermaphrodite.
Purposefully causing a plant to hermaphrodite is called selfing. Gibberellic acid or colloidal silver is typically sprayed onto the female plant. This technique is used to make feminized seeds and uses the plant’s ability to be both male and female to force a female plant to produce male flowers. The pollen contained in these male flowers can only produce female seeds. Just keep in mind that feminized plants should not be used for breeding, as they were produced without a true male, making them genetically inferior.
How to Plant Cannabis Seeds Indoors
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Growing cannabis at home can be a fun project and a nice way to have your own cannabis plants on hand. You may want to grow cannabis indoors due to inclement weather in your area or due to a lack of green space in your yard. Start by germinating the seeds. Then, plant the seeds in soil or in a starter cube. Once the seeds have been planted, care for them properly so they grow and thrive.
- After 12 hours, place the viable seeds on a towel.
Wet one paper towel and put it on a plate. Paper towels are thick enough to retain the moisture needed to help the seeds germinate. Place one paper towel under running water until it is wet to the touch, but not dripping wet. Use a ceramic dish or plate, as it will be strong enough to hold the towels and the seeds. The paper towel should cover the dish or plate.  X Research source
- If you do not have enough space on one plate for all your seeds, soak two more paper towels and put the remainder on a new plate covered in a wet paper towel.
Wet other paper towel and place it over the seeds. Make sure the wet towel makes contact with the seeds.  X Research source
- You can try using a heat lamp near the seeds to keep them warm. Do not warm the seeds up too much, as you do not want your heat source to dry out the paper towels.
- If the seeds become too dry, they could die and never germinate.
- Be very careful with the seeds as they open. Avoid prodding, pulling, or touching the seeds, as you do not want to damage the roots.
- Any seeds that have not opened and grown roots within a few days should be discarded, as they are not viable.
- As an alternative to soil, you can use starter cubes from your local nursery or online. Starter cubes are pre-cut growing pods made of composted bark. They contain a hole where you can place the cannabis seeds and grow them in good conditions. Basic starter cubes are inexpensive and easy to use.  X Research source
- If you make planting holes that are too shallow, the seed’s roots will not have enough soil to grow well. If you make the planting holes too deep, the seed will have a difficult time sprouting.
- Do not pull or tug at the seeds when you pick them up with tweezers. If they are stuck to the paper towel, wet the towel with water to make the seeds easier to pick up.
- Do not press hard on the seeds when you cover them, as this can disturb their growth.
- If you are using starter cubes, pinch the top of the holes in the cubes closed.
- Maintain a growing temperature of 75 to 85 °F (24 to 29 °C) for the plants so they thrive.
- Stick to a regular watering schedule so the plants get enough moisture. You can plan to spray the plants in the morning and then again at night so they get the water they need.
- Grow lights range from $200 to $1,200 USD depending on the size and model.
- You can get cool white grow lights at your local hardware store or online.
Avoid touching or handling the seeds as they grow. Touching or handling the seeds can damage them and stunt their growth. With the right growing conditions and care, your seeds should sprout and poke out of the soil within five to ten days.  X Research source
More than 12 hours of light a day for about 4-6 weeks as the plant matures will be enough. Once the plant is a decent size, you may induce flowering. Switch the plant to a timer of EXACTLY 12 hours of strong light (the more sunlight the plant gets, the more energy it can devote to flowering).
Yes, it is bad for the plant to have water constantly sitting at the bottom of the pot. It could make the roots rot over time.
You can actually find LED lamps made for growing plants online. If you don’t want to bother with that, you can just get a purple light to grow them under. There are many articles online talking about the effects of colored lights on plants.
If you plan on growing short, fat plants, they should be at least 6′ apart. You don’t want the plants rubbing on each other or shading the other plants. You will also want to select a spot to ensure all plants will receive maximum sunlight.
You can start as soon as you see two little leaves budding. During that time, make sure to use distilled water when watering them.
Cannabis thrives in a comfortable room temperature when grown indoors, or a little warmer – not too dry, not too humid. If it feels too hot or too cold for you, it’s probably too hot or too cold for your cannabis plants.
You can’t. You can try keeping it by a window, but you still won’t have much success. Lights aren’t that expensive, look on Amazon.
Yes, rain water is fine for any plant. The use of distilled water is to keep from adding tap water contaminants.
Keeping the plant from “stretching” is simple. Place the lights closer to the top of the plants. There are good video examples on YouTube showing two seeds started at the same time and placed under lights at different heights. The plant with inadequate lighting actually “reaches” for the light, growing tall and thin with longer internodal gaps. The seedling with closer light grows short and squat, with less stem between leaves (internodal distance), which means a better frame and plant structure for supporting the massive buds that you want to grow. As the plant grows, raise the lights with it. (Most folks suggest somewhere in the 16-30 inch range from source to canopy.)
The cultivation of cannabis is considered illegal in many jurisdictions. Make sure it is legal to grow cannabis in your area.
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This article was co-authored by wikiHow Staff. Our trained team of editors and researchers validate articles for accuracy and comprehensiveness. wikiHow’s Content Management Team carefully monitors the work from our editorial staff to ensure that each article is backed by trusted research and meets our high quality standards. This article has been viewed 1,330,133 times.
To plant cannabis seeds indoors, first soak the seeds in lukewarm tap water for 12 hours. Discard any seeds that float to the top. Then, place the seeds on a damp paper towel on a plate with 1 inch (2.5 cm) of space between each seed. Cover the seeds with another damp paper towel. Keep the seeds in a spot that remains between 70-80°F (21-27°C), and spray the paper towels with water whenever they start to dry out. The seeds will sprout in 2-3 days. When they do, fill pots or a growing tray 3/4 of the way with loose potting soil that has a pH between 5.8 and 6.3. Press the soil down lightly, leaving some air in it. Then, use a pencil to poke 1 inch (2.5 cm) holes in the soil. Place the sprouted seeds vertically in the holes and fill the holes with potting soil. Water the soil thoroughly and place the pots or tray in a spot that’s always 75°F (24°C) or warmer. Set up a grow light over the seeds and leave it on at all times. Water the seeds every day so the soil doesn’t dry out. The seedlings will emerge in 2-4 weeks. To learn how to use cool white grow lights to help your cannabis seeds grow, keep reading!
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