Managing Cannabis Fan Leaves
Managing and dealing with fan leaves on cannabis plants can have a huge impact on the quality and size of buds your crop produces. Keith Bouchard explains which fan leaves should be kept and which should be chopped.
Marijuana fan leaves, also known as sun leaves because they love to bask in the sun, or hand leaves (when they get really large), are the unofficial symbol of the cannabis plant. Recognizable by most and now a mainstream symbol, what are cannabis fan leaves and why do they matter?
When it comes to managing your fan leaves, there are several different schools of thought and each are correct in different situations. Don’t be afraid to follow these defoliation philosophies to increase your bud’s potential:
- Fan leaves are the powerhouse for photosynthesis so shouldn’t generally be removed.
- Removal, also known as defoliation of fan leaves lets light penetrate bud sites below the canopy and increases overall photosynthesis potential.
- Removal, also known as defoliation of dying, diseased or pest-ridden fan leaves is a good practice.
Fan leaves are the powerhouse for cellular growth associated with the node immediately following, or above, the fan leaf. Cannabis plants grow from the bottom up, with new growth appearing on the top of each node and new nodes growing out from the top of the plant. This is typically the direction of growth (upwards and outwards) of most plants, unless encountering intervention, such as an animal chomping off the top growth or the intentional application of pruning or training techniques, for example. The plant draws water and nutrients into the leaves through the roots, through the xylem to the leaves, and from the leaves through the phloem then on to the rest of the plant, allowing for photosynthesis and new cellular growth.
Fan leaves can sometimes grow to be more like monstrous gorilla hand-sized leaves that shade valuable light from the other parts of the plant. These sections might fully develop normally but have otherwise been shaded by these huge fan leaves. Consider removing the very large fan leaves to provide better light penetration overall.
When to Defoliate
Growers should consider defoliating under the following circumstances:
- If leaves are stressed by pests or disease or otherwise beginning to die off or turn yellow, it is generally a good idea to remove them. Enjoy a cleaner garden and the added benefits of opening up more light and air to the bud sites which were previously shaded.
- Before changing the photoperiod or light cycle from veg to flower (a.k.a. “flipping”), the plants will shoot up and spread out to claim as much light space for as many bud sites as possible. The change in lighting signals plants for flowering and building bud mass, hardwired into their DNA from millions of years experiencing earth’s seasons. Don’t be afraid to be aggressive at this stage since the plant has plenty of time to respond and produce plenty of healthy nugs.
- During mid-flower, perform another round of defoliation to further open the canopy and allow light to reach the inside of the canopy and increase bud density (weight) and overall cannabinoid and terpene profiles. Use this opportunity to open light to bud sites lingering in the shadows and further removal of yellowing leaves. Try to leave the green, healthy leaves that aren’t blocking too much light from the bud sites below.
General Fan Leaf Management
In general, fan leaves must be managed to keep a clean garden. If you are not concerned with attracting pests or having a clean garden, then you may not need to concern yourself with fan leaf maintenance. Nonetheless, it is helpful to understand why they are there and when it is appropriate to remove them. In addition to intentionally defoliating as a means to allow for more light penetration, there are other important times to remove fan leaves from plants in the cannabis garden. For example, when fan leaves die off they will eventually attract pests if not removed. Many organic gardeners will compost the dead or removed plant material. At a minimum, discard them so you are not giving pests a chance to munch on a meal while they are making the long journey into your garden, across your growroom floor, and onto your plants. Don’t make it easy for pests by providing them shelter and meals along the way.
Most of the time, pests come into the garden on the leaves themselves. This is another reason to remove any dead or infected fan leaves. It’s also wise to remove infested leaves in general to get the disease or pests and eggs out of the garden.
It’s a matter of balance: allowing as many bud sites as possible to get plenty of light while still leaving fan leaves on the plant to be the photosynthesis powerhouse for the associated branch or bud. Remember, buds also have plenty of smaller leaves to support photosynthesis. Just be sure the fan leaves left are associated with a section of the plant you want growing, like big colas.
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For proper environmental management, it is important to generally keep the plants open and airy not only to allow for light penetration, but also air movement throughout the plant. This will help prevent bud mold and rot, as well as increase the amount of CO2 available to the stomata of each leaf on every plant. We want to support certain areas of the plant, mainly big bud sites, so if the middle of the plant is full of little scrappy bud sites that end up just being larf (small buds) that could be used for cooking but not very good for smoking, consider removing the fan leaf and opening this otherwise shaded area to allow for more growth to these buds.
Removing a few fan leaves is one way to begin exposing bud sites that would otherwise be unusable flower. If you remove the light-blocking fan leaves above however, these larfy bud sites could end up being popcorn nugs, so decide based on the amount of air and light you are allowing into that section of the plant. Save plenty of fan leaves but try being strategic about it. Don’t be afraid to try this on one or two plants for a good side-by-side comparison.
For a more enjoyable experience using leaves for cooking or wrapping blunts, flushed fan leaves are necessary. While smoking, vaping, or cooking with processed cannabis material, use flushed leaves to ensure a smooth and enjoyable smoke, rather than a harsh coughing experience.
To properly harvest flushed fan leaves, pay close attention to the leaves as they yellow. Many fan leaves will do this naturally throughout their growth cycle, especially the ones that are at the bottom of the plant below the canopy. Harvest them as they yellow and before they dry out. The bottom part of the plant that gets less light usually will flush out their remaining nutrients and yellow off first. If you harvest them before they dry up and wilt, then they are still alive, yet flushed. This the exact state in which you would want to use them to wrap a blunt, etc. These fan-leaf wrapped blunts are also known as migars, or marijuana cigars.
Fan Leaves and Trichomes
Other reasons for processing fan leaves might be when trichomes have reached past the bud sites and sugar leaves, and all the way onto the fan leaves, which often happens with a successful and very resinous plant. Be sure to harvest these cannabinoid-rich leaves and use them for processing. These valuable leaves are also known as sugar leaves. The large fan leaves are also worth saving when they don’t necessarily have enough trichomes to be classified as sugar leaves, yet still have some yummy looking frosty trichomes.
Although trichomes are less dense on fan leaves, they contain plenty of THCA, THCVA and other valuable precursors to cannabinoids worthy of extraction that can be used in ointments or foods for anti-inflammatory and other beneficial effects. Research what these different cannabinoids do and decide whether your fan leaves are worth saving. Otherwise, remove them from the plant.
In conclusion, decide based on your garden’s needs. Based on a particular section of the plant, would you cut or keep the fan leaf? Do you want that fan leaf supporting its particular area of growth, or would it be better removed so it can open up air and light to another section and support more growth there?
Just remember that photosynthesis occurs in the fan leaves and they are the powerhouse for cellular growth at the above node, which supports a corresponding bud site. Bud sites also have plenty of smaller leaves to support photosynthesis. If it is confusing to determine where or when you cut, try doing this technique on just one plant in the garden — go for it and don’t hold back on that one test plant.
Be prepared to remove most of the fan leaves just before or just after flipping the lights from a vegetative 16-on/8-off schedule to a flowering 12-on and 12-off cycle. When performing defoliation of fan leaves, you are leaving certain ones on. You want to be sure the fan leaves remaining are supporting something that will pay off in the end. In some gardens such as outdoor crops, which get full sun coverage, or mass commercial production where labor is costly, no defoliation may be necessary.
Look at the big picture and figure out the plant at all angles. For example, in an outdoor garden, a plant is getting abundant sunlight and air and will naturally grow to the point where there’s plenty of fan leaves and bud sites that have all reached optimal sun. Defoliation of fan leaves is more beneficial in indoor gardens where the light is coming down from one direction — above the plant — and is not changing over time. It’s the same with the wind in an indoor grow, which is created by fans that have patterns or directional movement. Indoor plants indeed grow into a bit of a different shape for these reasons, and thus may require more defoliation and pruning than outdoor plants.
Defoliation may stunt plants for a couple days, so use these techniques strategically and when necessary. Don’t be afraid to test these techniques on a plant or two. Whichever direction you choose to take your fan leaves, one thing is true: fan leaves can be beneficial on your plant and removed from your plant. Learning and experimenting with removing some of these leaves can provide great benefit to your growing.
Fan leaves are an often overlooked, yet vital part of cannabis cultivation. After trying these fan-leaf management techniques, you are sure to better understand the cannabis plant and why it grows into the shapes it does given various conditions.
Written by Keith "Tree Frog" Bouchard | Founder & Co-inventor at Multiponics
Keith is the founder and co-inventor at Multiponics, an indoor gardening manufacturer and online boutique. Multiponics has a passion for pushing innovative ag-tech forward and is a consultant to the NASA-funded X-Hab project via the University of Colorado in Boulder.