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What causes Bananas on Cannabis Buds?

Cultivators studying the life cycle of cannabis plants will find the term “bananas”, “banners”, or “nanners” in reference to the flowering stage. The term describes the male organs that can develop on female cannabis buds. The cannabis community refers to plants with such features as hermaphrodites or “hermies” and attributes their development to a combination of genetics and stress. 

“Bananas” can be dangerous to a cannabis crop and may occur despite the cultivator’s utmost efforts. The most important skill to hone to minimize the chance of “nanners” developing is observation. The grower who regularly scouts their plants and learns about the morphology of cannabis flowers can reduce the impact “bananas” can inflict on a crop. 

It should be noted that “bananas” occur exclusively on female buds. This is different from true hermaphrodite plants that express both female flowers and male pollen sacks separately on the same plant. This article is primarily about “bananas.”

The Importance of Scouting Plants

One of the most useful habits a cultivator can develop is scouting their plants. This can be a tedious exercise but is a small price to pay to maximize plant health. Scouting will familiarise the cultivator with their plants’ growth habits and minimize surprises such as a pest outbreak or the development of “bananas” on their buds.

The most delicate stage in the lifecycle of the cannabis plant is the transition to flower. The cultivator needs to be most vigilant at this stage as the plants are using energy to stabilize themselves and may behave erratically, resulting in hermaphrodite cannabis plants or reduced pest resistance and vigour. Preventative scouting will place the grower in the best position to find hermie plants versus reactive scouting, which usually means it’s too late.

The scouting grower will benefit from a hand-held lens with an x10-x15 magnification and LED light or a microscope. This will definitively identify any pests or tissue formations that are the first sign of “bananas.” Focus on the axils of the plant (the space or angle in between the upper side of the leaves and stem) when looking for male flowers during the vegetative stage. These express as sacs of pollen known as stamen rather than female pre-flowers that are known as pistils.

The Formation of “Bananas” on Cannabis Buds

When the plants are in the flowering stage, environmental stress can cause them to develop “nanners.” Examples of such stress can include but are not limited to excessive heat or cold, light leaks, and light burn. The prudent grower should scout their plants even more vigilantly in the aftermath of any of these events.

“Bananas” on flowers are expressed as small, banana-like yellow or green protrusions on the bud either individually or in bunches. The size of these protrusions allows them to hide in the flowers undetected unless by regular scouting. They appear either straight or curved. 

Growers should keep watch for specks of yellow or green when inspecting their buds. These may appear quite starkly against the fine, delicate stigmas (white hairs) produced by developing flowers or amongst the protective calyxes. 

“Nanners” can form on cannabis buds anywhere from two to seven days after a stressful event (like a disrupted dark period). They can pollinate upon emergence, unlike sacs of male or hermied plants that must open to disperse pollen. Signs of accidental pollination can include a dusting of white/yellow particles on the surfaces of buds or leaves.

It is recommended that growers study pictures of buds with “bananas” or of male pollen sacs, particularly those that have opened. “Bananas” will look similar to the anthers inside the sac that store and release pollen.

The Danger of “Bananas” and Herm Plants

Healthy female cannabis plants produce dense, resinous, trichome-laden buds that are sought-after by growers and consumers. These flowers increase in density and size to give themselves the best chance for pollination. The larger surface area also translates to higher concentrations of cannabinoids and terpenes found in trichomes on the epidermis (the plant’s outermost layer of cells).

When pollinated by male plants, natural processes such as the production of cannabinoids THC and CBD are disrupted. This disturbance causes the plant to redirect energy and resources to produce seeds, degrading flower quality. Seedy buds ultimately stop increasing in size compared to unfertilized flowers, which can dramatically reduce the yield of a crop.

Pollen’s small size and the ease with which it can disperse means that even a single “banana” releasing pollen can derail an entire garden of healthy female plants. This is the danger posed by “bananas” and why the cultivator should practice maximum vigilance in observing their plants. Male cannabis plants should be removed from the grow space for the same reason.

In the Case of “Bananas”, Isolate

Growers who identify “bananas” on their flowers early in the flowering stage should isolate or destroy the plant(s) immediately to save their crop from pollination. If left unchecked, “nanners” that appear early in flower will have plenty of time to pollinate other plants. This highlights the importance of scouting and the peace of mind and sense of control it can give the grower.

If a cultivator finds their marijuana plants are rife with “bananas” deep in the flowering stage, a quick harvest may save flowers from pollination. “Bananas” that emerge during harvest time are less likely to pollinate flowers and produce marijuana seeds which is a time-consuming process.

“Bananas” can be removed from buds by hand or using sanitized tweezers. This will remove the immediate threat of pollination, although the plant may produce more. Hermaphroditism is, after all, a survival response.

Proactive Instead of Reactive

A valuable philosophy for the cultivator to adopt is to be proactive instead of reactive. This can be applied beyond scouting, as the proactive application of nutrients and management of the environment can have many benefits when trying to avoid plant problems. In the case of “bananas” and how they develop, this is of utmost importance.

Proactively managing the growing environment and thinking several steps ahead can minimize the stress that causes “nanners” to develop. Double-checking automated grow light systems during the transition to flower can prevent inconsistent photoperiods. Proactively overseeing the temperature and humidity in the grow room can head off any spikes or dips in conditions that could stress plants. 

Nutrient deficiencies, imbalanced pH, light, and nutrient burn are all examples of stressors that can cause “bananas” to form. They are also all variables that a cultivator can learn to control with decisiveness and precision. The reactive mindset takes action after a setback has already occurred; proactivity attempts to remove in their entirety the conditions that cause setbacks. 

The cultivator may find a grow diary or logbook extremely useful in keeping track of the conditions of their grow room. By recording variables such as temperature and humidity every day (especially highs and lows as informed by their hygro-thermometers), cultivators can chart any fluctuations in their environment. This informs growers of any stressors that may have developed that will help them make adjustments to their scouting regime or the environment.

Unpredictability comprises the most challenging part of preventing “bananas”, as they may appear anywhere after buds enter the flowering stage. Therefore, the grower would benefit from applying the same mindset to their plants, that is, to minimize any unpredictability in their growing environment. By adopting a proactive approach, growers reduce unpredictability.

The road to successful cannabis cultivation is full of situations that could derail growers from their journey. The grower with a plan should start with quality genetics with high germination rates such as those offered by Marijuana Grow Shop. Growers of all levels will find something to their liking at MGS, from robust feminized seeds, exclusive and on-schedule auto-flowering seeds, as well as rare regular cannabis seeds sourced from the world’s most passionate growers and seed banks.

Post author
Martin is a production horticulturist with experience in commercial cannabis cultivation and sustainable farming from his time with Emerald Cup Award-winning farmers Esensia Gardens in northern California's Emerald Triangle.
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