Turn over a typical bonsai pot and you may be surprised by the size of the holes underneath it. Compared with many ordinary plant containers, bonsai pots can have remarkably large drainage openings.
They are there for a very good reason.
Bonsai Roots Need Air and Drainage
Bonsai are commonly grown in free-draining soil mixtures designed to allow water and air to move through the root system. Large drainage holes help excess water leave the shallow container instead of remaining around the roots.
Of course, there is an obvious problem: bonsai soil could simply fall through those holes.
Growers therefore place drainage mesh over the openings before adding the growing medium. The mesh allows water to escape while helping to keep the soil inside the pot.
Drainage holes can serve another useful purpose too. Depending on the pot and repotting technique, wire can be passed through openings to help secure the tree firmly within its container while new roots become established.
Those oversized holes underneath your bonsai pot therefore aren’t a strange design choice.
They form part of a carefully considered growing environment designed to balance drainage, aeration and stability within the very limited space available to a bonsai’s roots.