Learn Hardcore Polish: Muszę posprzątać szuflady w szafie, bo leży tam za dużo rzeczy. - I must clean the drawers in the wardrobe because there are too many things lying there.

sprzątać – imperfective (focus on the process or repeated action)
- Muszę sprzątać szuflady w szafie.
  = I have to (regularly) clean the drawers in the wardrobe / I am obliged to clean them as a routine.
posprzątać – perfective (focus on a single, completed action)
- Muszę posprzątać szuflady w szafie.
  = I have to get the drawers cleaned (once, to a finished state).

In this sentence the speaker means “I must clean them up so that they end up tidy,” a one‑off task with a result. That’s why posprzątać (perfective) is used, not sprzątać.

What case is szuflady here, and why is it szuflady, not szuflad?

Szuflady is in the accusative plural, because it is the direct object of posprzątać:

Muszę posprzątać co? → szuflady.

Declension of szuflada (drawer, feminine):

Singular:
- Nominative: szuflada
- Genitive: szuflady
- Accusative: szufladę
Plural:
- Nominative: szuflady
- Genitive: szuflad
- Accusative: szuflady

In the plural, nominative and accusative both look the same: szuflady.
Szuflad is genitive plural, which you would use after certain quantifiers or in other genitive contexts, but not as a direct object here.

Why is it w szafie and not w szafę or w szafą?

The preposition w can govern different cases, depending on meaning:

w + locative → location, in / inside
- w szafie = in the wardrobe (where something is)
w + accusative → direction, into
- Wkładam ubrania w szafę. = I put clothes into the wardrobe.
w + instrumental – not used; w szafą is simply incorrect.

In the sentence w szafie, we’re talking about where the drawers are and where the things are lying, so locative is needed:

szafa (wardrobe, feminine) → locative singular: szafie
→ w szafie = in the wardrobe.

What case is rzeczy in za dużo rzeczy, and why that form?

In za dużo rzeczy, rzeczy is genitive plural of rzecz (thing).

With quantity words like:

dużo (a lot of)
mało (little / few)
trochę (some, a bit)
za dużo (too much / too many)
więcej, mniej, mnóstwo, etc.

Polish normally uses the genitive case after them.

So we get:

dużo rzeczy – a lot of things
za dużo rzeczy – too many things (or too much stuff)

Declension (relevant forms) of rzecz:

Singular:
- Nominative: rzecz
- Genitive: rzeczy
Plural:
- Nominative: rzeczy
- Genitive: rzeczy

So rzeczy can be both singular genitive and plural nominative/genitive; the quantifier za dużo forces the genitive plural reading here.

Why is the verb leży (singular) when rzeczy is plural? Could it be leżą?

In Polish, when you have an expression of indefinite quantity like dużo rzeczy, za dużo rzeczy, kilka książek, pięć krzeseł, the verb is typically 3rd person singular neuter, not plural:

Leży tam za dużo rzeczy. – Literally: There lies there too many things.
Jest tu dużo ludzi. – There are a lot of people here.
Stało tam pięć krzeseł. – Five chairs stood there.

So leży is correct and standard.

Using leżą in Leżą tam za dużo rzeczy sounds wrong or, at best, very unnatural.
However, without a quantifier, the plural agreement is used:

Na podłodze leżą rzeczy. – The things are lying on the floor.

So:

With za dużo rzeczy → leży
With plain rzeczy as the subject → leżą.

Can I change the word order to bo tam leży za dużo rzeczy or bo za dużo rzeczy tam leży? Does the meaning change?

Yes, both are possible. Polish word order is quite flexible, and here it’s mostly about emphasis and rhythm, not basic meaning.

These are all grammatical:

... bo leży tam za dużo rzeczy. (original)
... bo tam leży za dużo rzeczy.
... bo za dużo rzeczy tam leży.

Very roughly:

Putting tam earlier (bo tam leży...) highlights the location slightly more.
Putting za dużo rzeczy nearer the end (bo za dużo rzeczy tam leży) can make the amount of stuff feel a bit more emphasized.

In everyday speech, all three would be understood the same way; the difference is subtle and mainly prosodic (intonation).

Are bo and ponieważ interchangeable here?

Yes, you can say:

Muszę posprzątać szuflady w szafie, bo leży tam za dużo rzeczy.
Muszę posprzątać szuflady w szafie, ponieważ leży tam za dużo rzeczy.

Both mean because. The difference is in style:

bo – very common, neutral in speech, slightly more colloquial in writing.
ponieważ – a bit more formal / bookish, common in written language, essays, etc.

In everyday conversation, bo sounds more natural. In a formal text, ponieważ might be preferred, though bo is not “wrong” there either.

Could I also say Muszę posprzątać w szufladach w szafie? Does that change the meaning?

You can say:

Muszę posprzątać w szufladach.
Muszę posprzątać w szufladach w szafie. (a bit repetitive, but grammatical)

The nuance:

posprzątać szuflady – clean / tidy the drawers (themselves); this naturally includes their contents, but grammatically the drawers are the direct object.
posprzątać w szufladach – clean inside the drawers, i.e. the space/area within them.

It’s similar to English:

I must clean the drawers vs.
I must clean *in the drawers.*

In practice, both Polish versions usually mean “tidy the inside of the drawers,” but w szufladach puts more focus on the interior as a place.

What aspect and time reference does posprzątać have? How would I say “I have to be cleaning the drawers (ongoing)”?

Posprzątać is perfective. Perfective verbs:

do not have a real present tense; their “present” forms refer to the future:
- Posprzątam szuflady. = I’ll clean the drawers (and finish).
describe single, completed events.

In a modal construction like muszę + infinitive, the aspect still matters:

Muszę posprzątać szuflady.
= I have to (get them) cleaned once, to completion.

To emphasize an ongoing / repeated obligation, you’d use the imperfective:

Muszę sprzątać szuflady w szafie.
→ I have to clean the drawers (as a regular task / I’m required to clean them).

Polish doesn’t have a special “continuous” form like English be cleaning, so:

“I have to be cleaning the drawers (now, as an activity)” would typically also be
Muszę sprzątać szuflady (teraz).
The context and adverbs like teraz (now) convey the ongoing nature.

Why is muszę used instead of mam, even though English says “I have to”?

Polish usually expresses obligation/necessity with the verb musieć:

muszę – I must / I have to
musisz – you must / have to
musi – he/she/it must, etc.

So:

Muszę posprzątać szuflady...
= I must / I have to clean the drawers...

Using mam + infinitive is possible, but has a different nuance:

Mam posprzątać szuflady.
= I am supposed to clean the drawers / I am to clean the drawers (someone gave me this task, it’s on my list).

Roughly:

muszę – necessity, obligation (felt by you or imposed by circumstances).
mam + infinitive – assignment, plan, instruction.

In your sentence, the natural choice for “I have to” is muszę.

Could I say bo jest tam za dużo rzeczy instead of bo leży tam za dużo rzeczy? What’s the difference?

Yes, you can say:

... bo jest tam za dużo rzeczy.
= because there are too many things there.

The difference:

jest – neutral “there is / there are”, just stating existence/quantity.
leży – literally “lies / is lying”, adding an idea of things lying around, often suggesting mess or their physical position (flat, heaped, scattered).

So:

bo jest tam za dużo rzeczy – more neutral: there is too much stuff there.
bo leży tam za dużo rzeczy – subtly paints a picture of things lying around, e.g. clutter filling the drawers.

Polish often uses specific verbs like leżeć (lie), stać (stand), wisieć (hang) where English would just say “there is/are.”