Kwestia zdrowia rośliny jest ważna.

Because after kwestia (“issue,” “matter,” “question” in the sense of a topic), Polish normally uses the genitive case.

• zdrowie = health (dictionary form, nominative)
• zdrowia = of health (genitive)

So:

• kwestia zdrowia = the issue of health

This is very similar to English the issue of health or the matter of health.

For the same reason: rośliny is also in the genitive case here.

• roślina = plant
• rośliny = of the plant

So:

• zdrowie rośliny = the plant’s health
• literally: health of the plant

And the whole phrase:

• kwestia zdrowia rośliny = the issue of the plant’s health

Yes.

Here is the structure:

• kwestia — nominative singular, the main noun / subject
• zdrowia — genitive singular, dependent on kwestia
• rośliny — genitive singular, dependent on zdrowia

So the phrase is layered like this:

• kwestia
  
  • zdrowia
    
    • rośliny

In English, this is basically:

• [the issue] [of the health] [of the plant]

or more naturally:

• the issue of the plant’s health

Because ważna agrees with kwestia, which is a feminine singular noun.

Polish adjectives must match the noun they describe in:

• gender
• number
• case

So:

• ważny = masculine singular
• ważna = feminine singular
• ważne = neuter singular (and also some plural uses)

Since kwestia is feminine, you get:

• Kwestia ... jest ważna.

Kwestia is in the nominative singular because it is the subject of the sentence.

The sentence is built like this:

• Kwestia zdrowia rośliny = subject
• jest = “is”
• ważna = predicate adjective describing the subject

So kwestia is the thing that is important.

Not in the everyday sense of a question you ask someone.

In Polish, kwestia usually means:

• issue
• matter
• subject
• question in a formal/abstract sense

So here kwestia zdrowia rośliny means something like:

• the issue of the plant’s health
• the matter of the plant’s health

If you mean an actual spoken or written question, Polish more often uses pytanie.

Usually, in a normal neutral sentence like this, jest is kept:

• Kwestia zdrowia rośliny jest ważna.

Polish sometimes omits to be in certain styles, especially in headlines, notes, or very compressed speech, but in standard full sentences with a predicate adjective, keeping jest is the most natural choice.

So for a learner, it is safest to say:

• X jest ważny / ważna / ważne

rather than trying to drop jest.

No, Polish word order is fairly flexible, but different orders change the focus or emphasis.

The neutral order here is:

• Kwestia zdrowia rośliny jest ważna.

You could also say:

• Ważna jest kwestia zdrowia rośliny.
  = more emphasis on important

But the original version is the most straightforward and neutral.

So the meaning stays similar, but the information focus shifts.

By itself, rośliny can be ambiguous, because it can mean either:

• plants (nominative/accusative plural)
• of the plant (genitive singular)

But in this sentence, the grammar makes the meaning clear:

• zdrowia rośliny = the health of the plant

So here rośliny is understood as genitive singular, not plural.

Polish generally has no articles like English a/an/the.

So:

• Kwestia zdrowia rośliny jest ważna.

can mean:

• The issue of the plant’s health is important
• or sometimes more generally, Plant health is an important issue, depending on context

Context usually tells you whether something is definite or general.

Rośliny is pronounced roughly like rosh-LEE-nih, but that is only an approximation.

A few key points:

• ś is a soft sound, somewhat like a very soft sh
• the stress in Polish usually falls on the second-to-last syllable
• so ro-ŚLI-ny has stress on śli

Likewise:

• kwestia → KVES-tya
• zdrowia → roughly ZDROV-ya
• ważna → roughly VAZH-na

If you want a practical learner tip: focus on hearing and repeating the whole chunk:

• Kwestia zdrowia rośliny jest ważna.

Yes, but it means something slightly different in structure.

• Kwestia zdrowia rośliny jest ważna.
  = The issue/matter of the plant’s health is important.

• Zdrowie rośliny jest ważne.
  = The plant’s health is important.

The second sentence is more direct and simpler. The original sentence sounds a bit more formal or abstract because it talks about the issue or matter of the plant’s health.

So both are correct, but they are not exactly the same in tone.