Pokojovou rostlinu chci rosit při nízké vzdušné vlhkosti.

Because pokojovou rostlinu is the direct object of the verb rosit, so it has to be in the accusative case.

The dictionary form is:

• pokojová rostlina = nominative singular

In this sentence it changes to:

• pokojovou rostlinu = accusative singular

Both words change because the adjective and noun must agree:

• pokojová → pokojovou
• rostlina → rostlinu

This is a very common pattern with feminine nouns ending in -a.

It means an indoor plant or houseplant.

Even though pokoj literally means room, the adjective pokojový / pokojová / pokojové often means something connected with indoor or room use. So pokojová rostlina is not just any plant that happens to be in a room; it is the normal term for a houseplant.

Because Czech uses chtít + infinitive to say want to do something, just like English.

Here:

• chci = I want
• rosit = to mist / to spray

So:

• chci rosit = I want to mist / spray

Chci is the 1st person singular present tense of chtít.

Not quite.

• rosit means to mist, to spray lightly with water, usually onto the leaves
• zalévat means to water, usually by giving water to the soil

So if you are talking about increasing moisture around the leaves, rosit is the right verb. If you are talking about normal watering of the plant, you would usually use zalévat.

Při often means during, under, or in the conditions of.

In this sentence, při nízké vzdušné vlhkosti means something like:

• when the air humidity is low
• under conditions of low air humidity

So při is not really about physical location here. It is about the circumstances in which the action happens.

Because při requires the locative case.

The basic form is:

• nízká vzdušná vlhkost = low air humidity

After při, it changes to locative singular:

• nízké vzdušné vlhkosti

So:

• nízká → nízké
• vzdušná → vzdušné
• vlhkost → vlhkosti

This is normal adjective-noun agreement in the locative.

Yes, it is a normal expression meaning air humidity.

You may also see:

• vlhkost vzduchu = humidity of the air

Both are correct. Vzdušná vlhkost is a compact adjective + noun phrase, while vlhkost vzduchu uses a noun + genitive structure. In many contexts they are basically interchangeable.

Because Czech word order is much more flexible than English word order.

A more neutral order might be:

• Chci rosit pokojovou rostlinu při nízké vzdušné vlhkosti.

Starting with Pokojovou rostlinu gives that part a bit more emphasis or makes it the topic of the sentence. Czech often moves words around to show emphasis, topic, or what is already known from context.

So the sentence is grammatical, and the object-first order is perfectly natural.

Czech has no articles, so the sentence itself does not explicitly say the or a.

That means pokojovou rostlinu could mean either:

• the houseplant
• a houseplant

The exact meaning depends on context. Czech speakers usually understand definiteness from the situation, previous conversation, or general knowledge.

Yes. Rosit is an imperfective verb, and that fits the meaning well.

Here the sentence sounds like a general practice, habit, or ongoing intention, not one single completed act. In other words, it suggests something like:

• I want to mist the plant whenever the humidity is low
• I want to be misting it under low-humidity conditions

That is why an imperfective verb makes sense here.

Yes. That would also be natural.

For example:

• Pokojovou rostlinu chci rosit, když je nízká vzdušná vlhkost.

This is a bit more explicit and clause-based: when the air humidity is low.

By contrast:

• při nízké vzdušné vlhkosti

is more compact and slightly more formal or informational in style. Both are good; they just package the idea differently.

Yes. Czech often uses the singular to talk about something in a general way.

So pokojovou rostlinu can refer to:

• one specific houseplant, or
• a houseplant in general, as a type

This is similar to English sentences like A houseplant should be misted... or I want to mist the houseplant..., where context tells you whether it is specific or general.