Inconsistent Light Schedules & Light Leaks – When plants don’t get light at the same time each day, or if they’re exposed to light during their dark period (light leak). For photoperiod plants, this might be the largest contributor to hermies. Temperature – When temps get too high, hermies and nanners often appear. Cold night temps, or just large temperature swings in general, are also known to trigger bananas for some strains. Too-Bright Light – Like too much heat, and/or light that is too bright can stress your plants and trigger hermies.
This is most often caused by growers keeping their lights to close to their plants. You can light-burn your plants even when the temperature is under control. Major Plant Problems – Major plant problems like nutrient deficiencies, root rot, pH problems, light-burn and nutrient burn can all trigger hermies to start growing. Genetics – While stress plays a big role in the formation of bananas, the tendency to form them is genetic. This tendency is very common in the seeds of a plant that hermied. “Feminized” seeds, while always female, are much more likely to show the same herming traits as its parent. Growing seeds that were produced this way is naturally selecting to produce more buds that grow bananas. It is recommended that you remove plants showing bananas from your grow area immediately to prevent accidental pollination of buds. If the pollen being formed is allowed to make contact with your buds, those buds will stop focusing on making more buds and will turn all their “effort” into making seeds. If the plant self-pollinates, you will end up with a bunch of sub-par seeds that are likely to have the same problem.
Of the different types of “uncertain sex” cannabis plants, plants with mixed-sex buds (especially hermies with bananas) are the least predictable and this can make them more likely to cause unwanted pollination. This is partially because bananas may be hidden in the buds, and they don’t have a pollen sac that needs to burst to pollinate buds – it will start pollinating almost immediately. A grower who watches very closely can carefully pluck all bananas, but they are unlikely to be successful and will probably end up with at least a few seeds. Trying to salvage a plant that has started producing tons of bananas is NOT recommended, because it’s hard to get them all and you’ll end up with seeds. Even worse, once a plant gets started, bananas can appear in huge bunches overnight especially when the plant is stressed. Harvest the plant as soon as you can, before seeds get a chance to start forming. This section will explain what you can do as a grower to reduce your chances of running into hermies or bananas in your grow room… 1.) Avoid Inconsistent Flowering Light Periods & Light Leaks. Keep indoor lights on timer, and avoid changing the light schedule during the flowering stage if possible. Prevent outdoor plants from being exposed to street lights, flood lights or other types of artificial lights during the night. Respect the dark period – In the flowering stage it’s important to make sure all your plants (except auto-flowering strains) get at least 12 hours of uninterrupted darkness every night. No matter the strain, try to keep your plants on a consistent schedule throughout their lives, as this helps them set their circadian rhythms. And for photoperiod plants in the flowering stage, do not interrupt the plant’s 12-hour dark period with light for any reason . During the dark period your plant is “counting” the hours until sunlight appears, and interrupting this process is one of the most common ways to stress the plant into producing bananas or hermies. It can also cause your plant to revert back to the vegetative stage. Along with the point above, make sure you do not have any light leaks in your grow space, which could allow outside light to sneak in during the dark period. During the dark period your plants like complete darkness. If anything ever happens with your timer or power that causes your plant to get too much light or darkness, it’s important to correct your timer as soon as possible. But don’t worry about it too much if it happens just for one day. It’s usually okay if it happens only once, but be careful not to let it happen again since messing up the light schedule can cause hermies. It’s better for a plant to get a too-long day than a too-short night period in the flowering stage. So, for example, it’s better for it to get an 18-hour day than a 6-hour night. Cannabis plants “count” the hours of the night period, so it’s most important to make sure the night period is at least 12-hours long (longer is better than shorter for night periods). 2.) Maintain Proper Temperature Through Flowering Stage.
Maintain a comfortable temperature in the flowering stage, between 65-85°F (18-30°C). Avoid big temperature swings – temps should be slightly cooler at night than during the day. Don’t let the plant (and their roots) sit directly on a cold floor. Always use “hand-test” to make sure it doesn’t feel too hot in the top canopy of buds under the light. Put one of your hands (palm facing down) under your grow lights where the top of your plants are located and wait 10 seconds – if it feels too hot for your hand it’s too hot for the plants! Be careful of cold drafts at night in cool climates during the winter. 3.) Don’t Give Your Plants Too Much Light (Light-Burn) While generally more light is better for your cannabis plants, very high power brightness can light-burn your plants, which stresses plants, causes unwanted bleaching, and can trigger the plant to hermie on you. With high power LED grow lights and big HID lights, make sure to always follow the manufacturer’s specifications as far as the minimum distance from the top of the plants! Don’t keep your lights too close because even if the heat is under control, too much brightness can cause stress too. Light-burn is only common with high power LEDs (3W chipsets and bigger, x-lens technology, COBs, etc.) and big HIDs or perhaps multiple smaller HIDs (usually with an intense cooling system).
It is more difficult to “light-burn” your plants with fluorescent lights, CFLs, smaller HIDs, etc. – with these lights, you only need to worry about heat. High Power LEDs or HID Grow Lights Will Light-Burn Plants When Kept Too Close (yes, even if the temperature is completely under control) 4.) Prevent Major Plant Problems.