Iza kuće raste visoki suncokret koji uvijek gleda prema suncu.

Because iza normally takes the genitive case when it means behind in a location phrase.

• kuća = house
• kuće = genitive singular of kuća

So iza kuće means behind the house.

This is a very common Croatian pattern with prepositions: the preposition determines the case of the noun that follows it.

Croatian word order is much more flexible than English word order. Starting with iza kuće puts the location first, something like:

• Behind the house, a tall sunflower grows...

This sounds completely natural in Croatian. The speaker may be setting the scene first and then introducing what is there.

A more neutral English-like order would also be possible in Croatian, for example:

• Visoki suncokret raste iza kuće.

But the original order is very normal.

Croatian has no articles. There is no direct equivalent of English a/an/the in ordinary sentences.

So kuće could mean a house or the house, and visoki suncokret could mean a tall sunflower or the tall sunflower, depending on context.

Croatian usually shows definiteness through:

• context
• word order
• emphasis
• sometimes demonstratives like taj (that) if needed

Raste is the 3rd person singular present tense of rasti, meaning to grow.

Because the subject is visoki suncokret (a tall sunflower), Croatian uses singular verb agreement:

• suncokret raste = the sunflower grows / is growing

For plants, rasti is the natural verb to use. In English you might say there is a tall sunflower growing behind the house, but Croatian often simply says Behind the house grows a tall sunflower.

Visoki is the adjective tall, and it must agree with suncokret in:

• gender: masculine
• number: singular
• case: nominative

So:

• visok = basic dictionary form
• visoki suncokret = a tall sunflower

The noun suncokret is masculine singular, so the adjective takes the matching form visoki.

Koji is a relative pronoun, meaning who/which/that.

It introduces the relative clause:

• koji uvijek gleda prema suncu

This clause describes suncokret:

• visoki suncokret koji uvijek gleda prema suncu
• the tall sunflower that always faces the sun

So koji connects the second part of the sentence to suncokret.

Because koji must agree with the noun it refers to, which is suncokret.

Since suncokret is:

• masculine
• singular

the relative pronoun is koji.

It is also the subject of gleda, so it is in the nominative case.

Compare:

• suncokret koji... = masculine singular
• kuća koja... = feminine singular
• sunce koje... = neuter singular

Because the preposition prema requires the dative case.

• sunce = nominative
• suncu = dative singular

So:

• prema suncu = toward the sun / facing the sun

This is just like iza kuće: the preposition controls the case of the noun after it.

Prema suncu means toward the sun, in the direction of the sun. It fits very well with the idea of a sunflower facing the sun.

If you said gleda u sunce, that would mean more literally looks into the sun or looks at the sun, which sounds a bit stronger and more direct.

So in this sentence:

• gleda prema suncu = faces toward the sun

That is the more natural choice for describing the orientation of a flower.

This is a very normal kind of personification in both Croatian and English.

Literally, gledati means to look. But with things like flowers, windows, houses, or statues, Croatian can use gledati more loosely to mean:

• face
• be turned toward
• point toward

So suncokret koji uvijek gleda prema suncu is a natural way to say that the sunflower always turns toward the sun.

No, adverb placement in Croatian is fairly flexible.

Here uvijek comes before gleda, which is very natural:

• koji uvijek gleda prema suncu

Other orders may also be possible depending on emphasis, but this is the most straightforward one. Putting uvijek before the verb clearly means always modifies gleda.

Yes. Croatian allows several word orders, though the emphasis may change.

For example:

• Visoki suncokret raste iza kuće.
• Iza kuće visoki suncokret raste.
• Visoki suncokret koji uvijek gleda prema suncu raste iza kuće.

The original sentence sounds very natural because it introduces:

1. the place: iza kuće
2. the action/existence: raste
3. the subject: visoki suncokret
4. extra description: koji uvijek gleda prema suncu

So even though the order is flexible, the original version has a smooth, descriptive flow.