Indoor Wally has a military grade moisture barrier. This barrier creates a reservoir, allowing Wally’s tongue to continue wicking water to your plant’s roots long after you’ve walked away. This creates a healthy environment allowing your plants to absorb as much water as they need, while conserving water and helping to keep the soil’s nutrition in the Pocket.
Outdoor Wally has a slightly shorter moisture barrier than the Indoor Wally. While it still allows the plant’s roots to drink, it does not build a reservoir. This is because in outdoor situations you will need your Pocket to drain when there is an excess of water (a.k.a rain). If you are installing your Wally on a covered patio, you may want to opt for an Indoor Wally as the elements will not be an issue.