Learn Hardcore German: Dieser Moment im Garten macht mich ruhig. - This moment in the garden makes me calm.

Because Moment is the subject of the sentence, so it’s in the nominative case.
Moment is a masculine noun, so in the nominative singular the form of dies- is dieser.

Very short declension overview for dies- (singular):

Masculine: dieser (Nom), diesen (Acc), diesem (Dat), dieses (Gen)
Feminine: diese, diese, dieser, dieser
Neuter: dieses, dieses, diesem, dieses

So dieser Moment = this moment as the subject (the thing that does the “making”).

Why is mich used here and not mir?

Mich is the accusative form of ich; mir is the dative form.

The verb machen here is used in a causative sense:

jemanden ruhig machen = to make someone calm

The person who is being made calm is a direct object, which in German takes the accusative case:

Dieser Moment im Garten macht mich ruhig.
- Dieser Moment = subject (nominative)
- mich = direct object (accusative)

You would only use mir with verbs or structures that require a dative object (e.g. mir ist kalt, mir helfen).

What exactly does macht express here? Is it just “does”, or more like “makes me become”?

Macht is the 3rd person singular present of machen (to make / to do).

In this sentence it is clearly causative:

macht mich ruhig ≈ makes me calm / causes me to be calm

So it’s closer to English “makes me (feel) calm” or “calms me down” than to a vague “does”.

Why is it im Garten and not in dem Garten? Are they the same?

Yes, im = in dem. It is just a standard contraction:

in + dem → im (common and neutral)
in dem Garten (full form) is grammatically correct but sounds more formal or emphatic in everyday speech.

So:

Dieser Moment im Garten = This moment in the garden
Literally: This moment in the-the garden → contracted to im Garten.

Which case is Garten in, and why?

Garten is in the dative case because of the preposition in used in a locative sense (“where?”).

When in answers “where?” (location, not movement), it takes the dative:

in dem Garten → dative singular masculine → dem Garten

Since in dem is contracted to im, you get im Garten.

Why doesn’t ruhig have an ending like ruhg‑e or ruhig‑en?

Because ruhig here is used predicatively, not as an attributive adjective.

Attributive (before a noun, takes endings):
- ein ruhiger Moment, der ruhige Garten
Predicative (after verbs like sein, werden, machen, no endings):
- Ich bin ruhig.
- Dieser Moment macht mich ruhig.

In macht mich ruhig, ruhig describes the state of “mich” and stands alone after the verb; in this position, German adjectives do not decline (no extra ending).

Is ruhig here more like “quiet” or more like “calm”?

In this context, ruhig describes an inner state of the person, so it is best understood as “calm” / “peaceful”.

ruhiger Ort – a quiet place (little noise)
Ich werde ruhig. – I become calm (emotionally)

So Dieser Moment im Garten macht mich ruhig focuses on how you feel (calm, at peace), not primarily on the sound level.

Could I also say Dieser Moment im Garten beruhigt mich? What is the difference?

Yes, that’s correct and natural German.

macht mich ruhig
- Literally: makes me calm
- Slightly more descriptive, can feel a bit “softer” or more neutral.
beruhigt mich (from beruhigen)
- Literally: calms me (down)
- More compact verb; can feel a bit more direct, sometimes used when someone was previously stressed or upset.

In your sentence, both are fine; beruhigt mich emphasizes the process of calming you down, whereas macht mich ruhig emphasizes the resulting state.

Is Moment always masculine? How do I know its gender?

Yes, der Moment is masculine in standard German:

der Moment (Nom), den Moment (Acc), dem Moment (Dat), des Moments (Gen).

Unfortunately, genders mostly have to be learned with the noun. A good habit is to always memorize them in a package:

der Moment, der Garten, die Zeit, das Gefühl, etc.

There are some patterns (e.g., many nouns ending in ‑ent are masculine: der Student, der Präsident, der Moment), but they are not 100%.

Why is ruhig placed at the very end of the sentence? Could I move it?

The default word order in a simple German main clause is:

Conjugated verb in 2nd position: macht
Other elements in the “Mittelfeld” (middle field): mich
Non-finite parts and complements often go towards the end: ruhig

So … macht mich ruhig is the neutral order. You could say:

Dieser Moment im Garten macht mich ruhig. (most natural)
Dieser Moment im Garten macht ruhig mich. (grammatical but sounds wrong to native ears)

Adjectives that describe the result of the action (like ruhig) tend to appear after the object they describe, so they naturally end up toward the end of the sentence.

Can I change the word order at the beginning, e.g. Im Garten macht mich dieser Moment ruhig?

Yes, that is grammatically correct. It just changes the focus:

Dieser Moment im Garten macht mich ruhig.
- Neutral focus; starts with “this moment”.
Im Garten macht mich dieser Moment ruhig.
- Emphasizes “in the garden” (as opposed to somewhere else).

German word order is relatively flexible, but the finite verb must stay in second position, and the roles (subject, object) are mostly signaled by case, not by position.

Why are Moment and Garten capitalized?

In German, all nouns are capitalized, regardless of their position in the sentence.

So:

Dieser Moment im Garten macht mich ruhig.
- Moment = noun → capitalized
- Garten = noun → capitalized
- ruhig = adjective → not capitalized

This rule is one of the most consistent features of German spelling.