What it is
A prune of the main tip. Instead of cutting the whole shoot (as in apical), about 70-80 % of the new little leaves at the tip are cut and the base is left.
The name is an english acronym that means something like "oops, I missed": it was born from a badly done apical that gave more tips.
What it's for
Cannabis grows like a christmas tree: the main tip rules (called apical dominance) and the lower branches stay small. When that tip is removed, the hormone that made it rule (auxin) is redistributed and the lower branches activate.
With FIM, 3 or 4 tips usually come out where there was one. You get a more even canopy, light reaches all the tips better and more big buds come out.
When
In vegetative, with the plant healthy and with 4 to 6 nodes (about 3 to 4 weeks old). Never in flowering: it doesn't get to recover.
In autoflowers it's rarely used, because their vegetative is very short.
How to do it
- Sharp, clean scissors (wipe them with alcohol).
- Find the new shoot at the very top.
- Cut 70-80 % of that shoot in one clean snip. Don't take it off completely.
- Let it recover 7 to 10 days before another prune or switching it to flowering.
Common mistakes
- If you cut too little, it keeps a single tip; if you cut too much, it ends up as an apical (two tips).
- The result varies: sometimes 2 come out and sometimes 4. The first days the plant slows down: that's normal.
With other techniques
Topping is more predictable (always 2 tips) but the cut is bigger. LST cuts nothing: it ties down the branches. They can be combined: FIM + LST is one of the most common combos.
Before you start
Every prune or training is a wound: the plant spends energy closing it and adjusting. That is why it is only done with a healthy plant that is growing strong. If it is thirsty, has pests, mold, a deficiency or was just cured, let it recover for a few days first: one more blow to a weak plant can kill it.
▲ Pros
- Four colas: the cut that yields most
- Wide, even canopy
🎮 Practice it in UnderGrow
It's done from prune, in veg, and you pick only one technique per plant. At first it stresses (more on autoflowers) and halves growth for about 5 days (5 real h; 8 on autoflowers). After that it yields more: it adds colas, especially if the plant is healthy. First, check its health and stress: the technique adds its stress all at once and it can kill a plant with low health. Health only goes back up with the stress bar below 20 %.
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