This stops soil from falling through to the outside and also the roots from travelling out of the basket.
You can use a sheet of thick plastic perforated with holes at the bottom for drainage, personally I like to keep plastic out fo my planter pots unless UV stabilised and food grade. You can use a geo-textile for garden use or even an old piece of cotton such as a pillow slip. I use coco coir basket liners.
A general potting mix is good for flowers and a Herb and Veggie mix is suitable for potted herbs
There are endless opportunities for what can be planted in a basket. Ornamentals, annual flowers, Spring bulbs , herbs and vegetables can all be grown in this way.
Then why not use the out of the bag solution - the Root Pouch grow bags which are food safe, BPA free adan made of 100% recycled PET water bottles! Will not fall apart after a few seasons and are attractive and functional.
See how Larry & Eyvonne Hall grow a huge array of edibles in their Root Pouch bags!
Will I be sipping Pina Coladas in two years time? Well, you know that I'm not averse to having a go at growing most anything up here on the balcony...Corn, Blueberries and Grapes have been successful...so why not Pineapples?