LST - Plant Training and Shaping Techniques

How can you easily influence the shape of plants so that you get the most out of them? With proper training, you can achieve a rich harvest even from a smaller space. We have put together an overview of the most popular techniques used by both hobby growers and professional cultivators.

Experienced growers know that yield is not only about genetics or nutrition. The plant’s structure also plays a decisive role. Techniques such as supercropping, schwazzing or ScrOG make it possible to adjust growth in a targeted way, increase lighting efficiency and achieve significantly better results. Let us look at how they work and when to use them.

Topping: Trimming the tops

A basic technique that every grower should know. It consists of simply trimming the tops of the plants so that branching occurs at that point. Most growers trim young plants for the first time once they have three sets of true leaves, with the exception of some specific growing styles (for example SoG). After trimming, two new tops grow from the main stem and four side branches one level lower grow faster. The plant should then have six new tops at roughly the same height.

You can trim more than once, but only during the vegetative (growth) phase. After switching to flowering, removing the tops would only deprive you of future buds. The more often you trim the plants, the bushier they will be.

Fimming: Pinching the tops

A top-pinching technique that is said to have originated by accident, which is also where its English name F*** I Missed comes from. Fimming consists of trimming the top shoots so that about 20% remains on the plant. When successful, the plant creates four or more new tops close together instead of two. The result is low plants with buds packed closely together and a high yield.

Defoliation: Removing leaves

Leaves are where photosynthesis takes place and are indispensable for plants. Nevertheless, most growers regularly remove leaves from their plants. Usually this is done to improve the penetration of light and air through the canopy, which helps prevent mould and increases yields. However, defoliation must not be overdone, and it is necessary to know when and which leaves to remove.

During the vegetative phase: Among growers, there is a widespread myth that removing large leaves helps plants direct energy into forming new tops. In reality, this slows growth. Therefore, during the growth phase, remove only leaves that shade lower branches, grow inwards towards the plant, touch the substrate or are in the shade. Also remove yellowing or dried leaves.

During flowering: Although plants also need leaves during flowering, careful defoliation helps create a better microclimate and prevents mould. Especially in indoor growing, it is a good idea to remove leaves from the lowest levels where no light reaches. Likewise, remove larger leaves that shade ripening buds. As harvest approaches, regularly remove yellowing and drying leaves as well.

Schwazzing: Extreme defoliation

Leaves that receive enough light photosynthesise and create carbon, which is a source of sugars for the other parts of the plant. On the other hand, shaded leaves store carbon and photosynthesise only minimally. Therefore, removing shaded leaves helps plants make better use of the available carbon and leads to higher yields.

Schwazzing is a method popularised by J. Haupt in the book “Three A Light”, which consists of repeated extreme defoliation during the first three weeks of flowering. The result is shorter plants with long buds, including on the lower branches.

How to do it: On the first day of flowering, remove all large (fan) leaves. This will not only increase the permeability of the canopy, but also force the plants to focus on developing new leaves instead of elongating the stems, so they will remain more compact and will not stretch as much. Do not forget that by removing the large leaves, your plants have lost a significant reserve of nutrients. Over the next ten days, increase the nutrient dose by about 20% with a formula that is higher in phosphorus and potassium (flowering formula).

Carry out the second defoliation on day 20 of the flowering phase and again remove only the large leaves. Take care not to damage the developing flowers. In the third week of flowering, the plant has already passed the stem-elongation phase and, thanks to the first trimming, the buds should be growing close together. After the second trimming, the flowers will develop close together and the result will be long buds. One of the advantages of schwazzing is that, unlike the traditional method, there is no need to trim the lower branches, because they will also receive enough light thanks to the absence of leaves and you will harvest nice buds on them.

ScrOG: Weaving into nets

Screen of Green (ScrOG) is a plant-training technique that shapes plants into a horizontal plane using a net or grid. This has countless advantages, especially in indoor growing under artificial lighting. If you leave your plants unattended, they will always grow more upwards than outwards. The main branch will then be too close to the grow light, while the tops in the lower levels will receive too little light. The aim of weaving into a net is to create a uniform surface of tops that all receive the maximum energy from the lights.

How to do it: Place the support net 20-30 cm above the base of the plant. Start weaving the tops as soon as they grow 5 centimetres above the mesh openings. Gradually guide the main branches in all directions, and once almost the entire net is filled, switch to flowering and continue weaving for the next two to three weeks until full flowering begins and the plants stop stretching.

LST: Bending stems

LST (Low Stress Training) is a gentle plant-training method in which branches are slowly bent and tied down. Bending stems can be used in many ways, from spreading the canopy and exposing lower branches to light to training photogenic cannabonsaïs. Alternatively, bending can be used to deal with overgrown plants in the early flowering stage.

How to do it: Using soft tying wire, string or plastic clips, start bending the main stem and later also the side branches away from the centre of the plant. This will expose more leaf area to the light and encourage the growth of new shoots. Carry out LST exclusively during the vegetative phase and in the first weeks of flowering, while the stems are still flexible.

Supercropping: Breaking stems

Supercropping is a technique in which you deliberately disrupt the internal structure of the stem so that it bends but does not break. The plant responds to the stress by strengthening the damaged area and growing more intensely in other parts. Breaking stems is one of the advanced techniques and requires a steady hand.

How to do it: Choose a flexible stem in the growth phase and gently squeeze and massage it between your fingers until it gives slightly. Then bend the shoot in the desired direction. If the branch does not want to stay in the new position, tie it down or support it. Within a few days, the plant will form swollen joints on the damaged stem.

Training is a way to achieve better results without having to change nutrition or lighting. Start with simple techniques such as topping or LST, and gradually discover what suits your plants best.

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