Learn Hardcore Japanese: oiwai no tame ni hana wo kaimasita.

In Japanese, you can omit the subject (who is buying) when it’s clear from context. Here, the speaker is understood to mean “I” or “we,” so there’s no need to say 私は or 私が.

What does the お in お祝い do?

The お is an honorific (polite) prefix. It makes 祝い (“celebration” or “congratulation”) sound more respectful or formal. Many common words take お (e.g. お茶, お金).

Why is there a の between お祝い and ため?

When you attach ため (“sake,” “purpose”) to a noun, you connect them with の. So お祝いのため literally means “for the sake of (the) celebration.”

What does ために mean, and how is it used?

ために expresses purpose: “in order to” or “for the sake of.”
• You can attach it to a noun with の (as above).
• You can also attach it to the plain form of a verb (e.g. 勉強するために “in order to study”).

Why not just say お祝いに花を買いました? Isn’t に enough?

Both are grammatically correct, but there’s a nuance:
• お祝いに花を買いました treats お祝い like an occasion or event (“I bought flowers on/at the celebration”).
• お祝いのために花を買いました emphasizes purpose (“I bought flowers for the purpose of celebrating”).
Use ために when you want to focus on intentional purpose.

Why is 花 followed by を?

The particle を marks 花 as the direct object of 買いました—it’s what was bought.

Why is the verb 買いました at the end of the sentence?

Japanese follows a subject–object–verb (SOV) word order. Verbs (and adjectives) typically come at the end.

Why is the verb in the polite form 買いました instead of the plain form 買った?

買いました is the polite past form (–ます／–ました). It’s used in formal or polite contexts. The plain past form 買った would be more casual. You choose based on how polite you want to sound.