Almost everything we do impacts other people in some way.
Please bear in mind that gardening in general and trees in particular can lead to neighbourly problems.
If you damage another persons property or your livestock escape and cause damage then you are likely liable.
A quick word about cannabis:
This website is hosted in the United Kingdom where the growing of cannabis is illegal, despite the fact that most of the technology and practices were developed from the indoor grow operation.
As such there is no information about the growing of cannabis on this site nor can we condone the practise.
Home grown Tobacco:
You also need to be aware that if you grow tobacco, you are obliged to pay duty to HMRC on the finished product by weight.
I believe this is a Europe wide directive except that in typical Government tradition there is no method in place to collect any revenue from home growers. Take this to mean that if you grow a plant or two for your own consumption and do not sell or give away the product then they do not care!
Guerrilla gardening, the practise of growing plants on someone else land without their permission is also illegal in the United Kingdom.
That said, provided you use wasteland or unused land, are careful to avoid dumps and toxins and don't get caught you are unlikely to end up in front of a magistrate for planting broccoli on a verge.
On the other hand, someone else may steal it, an animal may eat it and you may be liable if you do any damage to the land you are using.
Always make sure you have permission and honour any sharing agreements you set with the land owner.