Cut the bottom off a plastic pot to contain invasive plants & bury in the ground. I have been doing this for a few years & works great for containing plants that tend to spread, but that I still want to plant in the garden. This also works good for planting a plant in an area that tends to get filled with roots etc. from other plants. I will use a larger pot so that the plant can spread it's roots and grow deeper roots, but keeps other tree roots from choking out the one I planted.
Aspirin For Plant Growth: Tips On Using Aspirin In The Garden - An aspirin a day may do more than keep the doctor away. Did you know that using aspirin in the garden can have a beneficial effect on many of your plants? Salicylic acid is the active ingredient in aspirin and is derived from willow bark. Learn more here.