We have all asked ourselves this question standing in front of the netting looking confused.
The answer to this question is to first ask yourself, what do I need it for and what do I need to keep out?
Obviously you will need different netting to keep out small animals, birds then insects.
Then, when do I need this netting?
This will be in different stages of the growing.
And finally, why do I need to use netting?
Do I want to eat a lot of chemicals and let them get into my system - Um No.
So let's start with the small stuff. You are growing tomatoes, so you need the plant to get to a stage where it is healthy and starts producing flowers. For this you will need a tough netting to keep off the possums, turkeys or whatever you have in your area that eats your food. I would use a pre-stretched netting with about 1cm holes (I will talk about why the holes later). This netting needs to be on a frame away from the plant because if the animals think they have any chance of being able to eat that plant they will, so make sure the plant is not touching the netting. Use a frame and keep the netting tight so that the local wildlife cannot get caught and hurt themselves in the netting. We don't want them to eat our food but we also don't want to hurt the wildlife. Also, sometimes we need to find a sacrificial plant so that the hungry critters are kept happy and don't try to eat the good stuff!
So once this is all do and you start getting flowers on the plant they need to be pollinated by insects to produce the fruit so make sure you have holes in it so they can fly in. The next thing you will notice if you don't change the netting is you will start to have your fruit eaten by the insects so it is now time to move to a smaller netting as the one below.
Above: you can see teh fine netting is just draped over the tomatoes and chillies. This is ok as you can see I already have my larger netting around the whole thing to keep out the big stuff
This will let your fruit grow big and juicy chemical free. Remeber you are what you eat