Picnic adjectives are listed in this post. Each word below can often be found in front of the noun picnic in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing PICNIC.
annual, big, covered, delightful, few, first
grassy, great, huge, ideal, impromptu, indoor
large, little, long, lovely, nearby, nice
old, outdoor, own, perfect, perpetual, pleasant
romantic, school, several, shaded, small, wooden
Hope this word list had the adjective used with picnic you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.