A well rooted plant can rot spontaneously if the pot is overheated in wet
conditions. Roots can clog up the drainage ports of a container, allowing
water to pool up. This will drown roots which rot and can spread to the
Up-pot plants to large containers.
Use a 50% perlite/soil mix for good drainage.
Water thoroughly, then allow the soil to dry out before watering again
(never keep them always wet & soggy)
Black pots in full sun can overheat-damaging roots wrapped around inside.
If soggy it can cook the roots.