WordNet records no synonym and no antonym for planting. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the act of fixing firmly in place
“he ordered the planting of policemen outside every doorway”
a collection of plants (trees or shrubs or flowers) in a particular area
“the landscape architect suggested a small planting in the northwest corner”
putting seeds or young plants in the ground to grow
“the planting of corn is hard work”
Synonyms, antonyms and the broader and narrower relations for planting come from Princeton University’s WordNet. Full sources and licences.