Pruning cannabis plant typically means topping, fimming or using the lollypop technique. It can seem high-risk & daunting. Especially for less experienced growers. Some growers, probably a minority, don’t believe in pruning their plants. But many others find that pruning cannabis allows better plant growth and more/bigger blooms. Pruning/defoliating cannabis can also improve air flow around the plant, reducing the chance of some diseases such as bud rot.
Pruning cannabis plants for better yields
Pruning cannabis pro’s and con’s
Many routinely prune/defoliate their cannabis plants and get great results from their efforts. But some growers dislike the concept of deliberately removing branches and heavy defoliation. There are arguments both ways.
Arguments against cannabis pruning
Some older-school growers (and many outdoor growers) don’t fully subscribe to routine cannabis pruning or defoliation (leaf removal), citing the following concerns:
Arguments in favour of cannabis pruning
Ambitious indoor cannabis growers aim to maximise bud production from a compact tent/grow-room. This means that cannabis pruning, and regular defoliation is seen as quite normal by many.
Pruning vs defoliating cannabis plants
Pruning and defoliation are terms that are sometimes used interchangeably, which can cause confusion. To many, pruning means the use of plant ‘surgery’ techniques such as topping, lollypopping & fimming – where plant material/branches are cut away with sharp pruning scissors. Defoliation means leaf removal.
More about the lollypop technique, topping, defoliation and plant training
Lollypopping a cannabis plant, is the removal of lower branches (often these are shaded & lower yielding) in order to allow plant growth to be focussed on the main bloom points.
There are a variety of cannabis LST (low stress training) techniques as well as cannabis HST (high stress training) techniques which can also be used to great effect.
Defoliation refers only to leaf removal. Defoliation is common practise whether growing autoflower seeds, feminised seeds or regular cannabis seeds.
Cannabis leaves absorb energy from light and use it to fuel plant development via the process of photosynthesis. This allows growth of roots, stems, branches, buds, plenty of leaves and cannabis trichomes.
Many modern vigorous cannabis seed varieties can produce huge amounts of leaves during their lifetime. Most growers pluck excess leaves (defoliation) from their plants to improve light penetration.
For the more adventurous beginner, perhaps with an experienced friend, yes. But it remains good advice for less experienced growers to get used to growing their plants naturally.
Mastering the basics of nutrient management, plant growth and light control are valuable skills to gain before attempting more adventurous grow techniques.
That said, defoliation of excess leaf growth (e.g. that which blocks lower bloom points) is a low-risk activity. Even for rookie growers.
One alternative is to tuck the larger fan leaves behind the blooms – ‘leaf tucking’. This allows the buds to bathe under powerful direct light and swell to optimum proportions.
The fan leaves don’t have to be cut off, merely repositioned & tucked away. Leaf tucking is preferred by those averse to defoliation.
Another option would be to take only parts of the foliage away. Using scissors to cut away about 1/3 to 2/3 of the leaf material. This still retains some foliage to absorb light energy whilst at the same time delivering improved airflow and more light penetration.
Can you prune both indoor and outdoor cannabis plants?
Yes. Although pruning is often seen as more relevant to indoor cannabis growers who are often aiming for maximum yield in relatively cramped conditions with several plants in close proximity.
Outdoor growers, often with plants that can exceed 2-3m /7-10ft, can find it impractical to defoliate an outdoor monster and may need stepladders to do so.
Remember also, that the sun travels across the sky, ensuring there are few permanently shaded areas on outdoor plants. Many outdoor growers also enjoy far less cramped conditions than an indoor grower. Without plants crammed together in close proximity, outdoor plants are often left to grow in the natural way.
However, some outdoor cannabis growers do use pruning techniques such as topping, especially on taller cannabis seed varieties. Topping is the removal of the growing tip of the plant, resulting in a shorter, bushier plant.
For tall-growing outdoor cannabis seed varieties, taming final plant height is useful to keep the plant out of sight. Some outdoor growers also use the SCROG method to control their plant height.
When to prune cannabis plants
The answer partly depends on the strain you are growing and the method you are using. Topping a short indica seed variety during the vegetative growth phase may seem less relevant than topping a stretchy sativa seed variety. One general guideline is to top just above the 5th node on the main stem.
It may be necessary to defoliate your plants irrespective of the type of weed seeds you are growing. The timing of defoliation depends on the level of excess foliage. Some defoliate their cannabis plants several times – using their experience to know when & how much.
During veg and bloom, the main concern is not to over-defoliate and stress/stunt the plant. But as illustrated in the pictures further below, surprisingly extensive levels of defoliation can be done without harming long term plant development. Especially when growing in a hydro-system with speedy growth and quick recovery times.
Cannabis topping is done in veg, rather than bloom. The idea is to create a bushy plant (more eventual blooms) with the growing tip removed and allow the plant to recover before flowering begins.
Can you prune cannabis plants in the flowering stage?
Defoliation of excessive leaf material is quite normal in bloom. But topping/fimming cannabis during the flowering period (as the blooms are forming/swelling) tends to reduce the final yield and is considered poor practice.
However, many routinely remove (lollypop) lower, unproductive branches that are unlikely to contribute significant bud quantities. This can be done in bloom, simply cut the branches off with pruning scissors. The potential (small) yield of fluffy bud is sacrificed allowing the plant to focus growth on more productive areas.
Can you over-defoliate cannabis?
The big question that vexes so many! Clearly there is little value in defoliating a young, small plant. But as the plant grows larger, how much leaf material can be removed?
One good example of extensive defoliation can be seen from the most advanced growers that push their plants to the limit with LED lights and hydroponics.
The following picture of Auto Daiquiri Lime shows just how much defoliation can be done to a plant without damaging growth. This heavily defoliated plant was then super cropped and placed under a SCROG net.
The same plant went on to have 2 further similarly heavy defoliations before producing an astonishing 1.3Kg/2.9lb dry yield. Check out the full Auto Daiquiri Lime grow review for more details, and note that the best weed seed varieties can withstand far more defoliation and HST than you might imagine.
Before & after Auto Daiquiri Lime defoliation. One of 3 such defoliations before delivering a 1.3kg dry yield.
Many outdoor growers have had the misfortune to see a plant heavily defoliated and pruned by slugs/snails. Even when a plant has been severely stripped of foliage it can still deliver. As shown by this slug attacked Auto Euforia (full grow review here). Despite being little more than a stem after the slug attack, the Auto Euforia went on to deliver a top-rated harvest!
Auto Euforia UK outdoors, extreme slug defoliation but still delivers bumper harvest.
How to prune cannabis plants for the best effects
Topping a cannabis plant should only be done on strong, healthy plants that are able to tolerate the process. If your plant appears to be below par it makes sense to wait. Topping a weak plant can slow development.
Although cannabis is tough enough to cope with various topping techniques, many prefer to wait until their plant has 5 nodes on the main stem. Then the main stem is cut above the 5th node with clean, sharp pruning scissors or a razor.
Why cut above the 5th node? Because this allows several branches below the cut. This should ensure plenty of lower/lateral growth. But many growers use their own pruning method. Stretchier strains might be topped above the 4th node.
Compact indica cannabis seed varieties might be topped above the 6th/7th node, for example. Some growers also top the side branches, perhaps above their 2nd/3rd node. This produces even more side shoots and future bloom points.
What to do after pruning your weed plants
Once topped, watch and wait. Over a few days you should notice new side shoots starting to grow below your cut. Continue to water/feed your plant as required and ensure normal light levels.
Usually, 2 new growth points emerge from the node below the cut. With the ‘FIM” (F*** I Missed) technique, a cut is made deliberately through the growth tip, rather than above a node. When FIMmed correctly, 3-4 or more new growth tips can be produced. But the FIM technique is notoriously tricky to perfect, hence the name.
Bonus tips for pruning cannabis plants effectively
- Any dying, or unhealthy-looking leaves can be prioritised when defoliating.
- Leaves that are blocking light from emerging bloom points/buds are also priority targets during defoliation.
- When using the lollypop technique, simply remove the lower branches once the plant has had several weeks of vegetative growth. You can continue to lollypop and remove unproductive lower branches in bloom.
- If you see a branch that you know will struggle to develop (based on your grow room layout/experience), remove it sooner rather than later. This saves your plant investing too much energy in it.
- The cautious grower can take encouragement from some of the ‘before & after’ pictures that show how much pruning/defoliation can be done without adverse effects. The best cannabis seed varieties have been selectively bred over many generations to produce the resilient growth needed to survive such heavy defoliation/pruning.
New cannabis seeds!
