"I've been wondering how to go plastic free on my allotment and in my garden, it really is a challenge. The first problem is plastic pots as they can't usually go in the recycling. I reuse these wherever I can and I have discovered that some garden centres will take them back for re-use/recycling and a charity has started to collect them re-use; see www.potto.product.co.uk for the nearest collection points to us which are currently RHS Wisley and Woodcote Green Garden Centre. Hoping it will soon be possible to buy plants in non-plastic pots
Compost and plant foods are a real problem as nearly they all come in plastic bags/containers. I'm experimenting with making comfrey tea to use as a plant food, you put a pile of comfrey or nettle leaves in an old dustbin, fill it with water and put a lid on and leave it for a few weeks (until the smell has gone!) then you have a great homemade plant food which you can store in old glass bottles. Might try making my own potting compost: 2 parts compost: 1 part sand and 1 part leaf mould, but sand comes in a plastic sack!
Slug control is also a big problem... I garden organically and there is one product which is organic and doesn't harm other wildlife which I use when all else fails, but it comes in a plastic container, so I am experimenting with dried crushed egg shells with some success. Discovered that Monty Don on Gardeners World is trying to go plastic free and there is quite a bit of information on their web site.