HOW TO KNOW ABOUT DRAINAGE
When using pots outdoors it is necessary to have sufficient drainage to allow excess water to be removed from the pot and avoid damaging the structure. Be sure that excess water is properly drained from pots before leaving them outdoors in cold weather.
If you are using your planters indoors, drainage holes are not recommended
Drainage of Round Pots

Drainage of Round Pots
Drainage of Square Pots

Drainage of Square Pots
Drainage of Rectangular Pots

Drainage of Rectangular Pots