2) 宝特瓶盖鑽一孔倒立插入泥土， 虹吸管现象
Air pruning is the latest gardening technique using planter pot with holes at the sides. When roots grow and hit the wall of the normal pot without holes, it would go around in circle along the wall, not taking the nutrients of the soil to the maximum. If there are holes, the root tips would dry out, signaling the plant to grow more roots in the soil, hence taking in maximum nutrients from the soil.
How to make air pruning planter pot using a laundry basket: