I recently made a Vertical garden and The top row of bottles was to close to the ceiling.
So I had to modify those bottles for "sideways growing.
Here is how I did it.
Step 1: Tools
I went low-tech on this one.
You need a knife and a Hairdryer.
It will be easier with a heat gun. It doesn't overheat as quick.
Step 2: Cut Your Slit
Take the knife and cut about 2/3 down from the neck of the bottle.
From one end to the other.
Step 3: Heat Up
Heat up the general area you need to bend.
After a minute your plastic will become a little bit softer.
Bend it with you hands inwards.
BE CAREFUL: It is much wiser to use gloves with this.
Step 4: Hold On: Fold Far Enough
The picture above shows a bad fold.
If this happens: Reheat and refold.
Step 5: Conclusion
This was a quick project that was super simple.
I hope you'll enjoy it.