How many letters does the top answer for “of plants and animals; not growing or living in groups or colonies” have?

The most common answer is nongregarious (13 letters).

Crossword clue: of plants and animals; not growing or living in groups or colonies

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

nongregarious 13 letters wn-def

of plants and animals; not growing or living in groups or colonies

nonsocial 9 letters wn-def

of plants and animals; not growing or living in groups or colonies