Learn Dutch: In de herfst vallen de bladeren. - In the autumn, the leaves fall.

The singular word for a leaf is het blad. This is one of the few Dutch nouns that gets an -eren ending in the plural instead of just -en or -s. Notice that the vowel also changes its sound: the short 'a' in blad becomes a long 'a' sound in bladeren.

I have sometimes seen bladen as a plural. What is the difference?

Het blad has two meanings: a leaf on a tree, or a sheet of paper or magazine. When you mean leaves on a tree, you use the irregular plural bladeren. When you talk about sheets of paper, you use the regular plural bladen.

Why is the verb vallen placed before the subject de bladeren?

This is because of the Verb Second rule. The sentence starts with the time phrase In de herfst (In the autumn), which takes up the first position. The verb vallen must come second, so the subject de bladeren gets pushed to the third position. This swapping of the subject and verb is called inversion.

Do we always use the preposition in for seasons in Dutch?