Once upon a time had some red-bloomed Hibiscus that I planted in front
of a window that were very hardy for a number of years. Green, lots of
blooms, bounced back annually from freezes after trimming to stumps
and grew like weeds again once the weather warmed.

Circumstances required their removal and they didn't survive
replanting. I tried to replant new ones from Walmart in the same basic
spot but they never really seemed to take. Even after several months
they would only grow if watered constantly and the first freeze killed
them. I apparently unwittingly did something right with the first
ones but don't know what it was.

What's the right way to go about it to ensure solid root establishment
as quickly as possible?

Thanks in advance for all input.