Questions & Answers about Rosnące zboże potrzebuje słońca i wody.
How is rosnące formed here, and why does it end in -e?
It is an active adjectival participle, which acts like an adjective meaning "growing". To form it, take the "they" form of the present tense of rosnąć (rosną), and add -cy. Since it's modifying zboże, which is a neuter singular noun in the nominative case, the basic masculine ending -ący changes to the neuter ending -ące, giving us rosnące.
Why are the words for "sun" and "water" in the genitive case (słońca and wody) instead of the accusative?
In Polish, the verb potrzebować (to need) strongly requires its object to be in the genitive case. Even though "sun" and "water" are the direct objects of the sentence, you must use the genitive forms słońca (from słońce) and wody (from woda).
Could I just say zboże, które rośnie instead of using rosnące?
Yes, you absolutely can! Using a relative clause (zboże, które rośnie - grain that is growing) is very natural in Polish and means the exact same thing. The participle rosnące just allows you to express the same idea more concisely by putting it directly in front of the noun, exactly like the English "-ing" adjective.
Is zboże plural here? The -e ending makes it look like a plural word.