This model of EverGrow Bag was made in response to a material shortage of our original white base material. We are selling off left over stock at a reduced rate. These EverGrow Bags have the base made of the same materials as the side walls (tough green outer layer and a fuzzy grey inner layer). Planted in the ground there won't be much of a difference compared with our white -based bags. Finer roots will grow directly down through the base material until they get big enough to be squeezed, and slow down their vigour. This style bag has slightly increased drainage compared to the white based bag.
If the bag is sat above ground over soil or grass, then the roots will grow down through the bottom of the bag and adhere the bag to the ground. This can be inconvenient but on the other hand if you don't plan to shift it around then the additional moisture and nutrients are useful for the tree. If shifting in future, just take a spade and cut through any roots growing downwards in order to move the bag. Alternatively you can place the bags on a hard surface or use a pot saucer to keep the roots from reaching the soil.