Learn Hardcore Italian: I fiori appassiscono senza acqua in giardino. - The flowers wilt without water in the garden.

In Italian, to speak about things in a general sense you put the definite article before plural nouns. Thus I fiori means “flowers (in general),” whereas in English we simply say flowers without an article.

What tense and person is appassiscono, and how does appassire conjugate?

Appassiscono is the present indicative, third person plural of appassire (“to wilt/with er”). Here’s the full present tense:

io appassisco
tu appassisci
lui/lei appassisce
noi appassiamo
voi appassite
loro appassiscono

Should appassire be reflexive (with si) since the flowers are experiencing the action?

No. Appassire is an intransitive, non-reflexive verb in Italian. The action happens to the subject itself, but you do not add a reflexive pronoun. Saying I fiori si appassiscono would be ungrammatical.

Why is it senza acqua and not senza l’acqua or senza dell’acqua?

After senza you normally drop the article, especially with uncountable or abstract nouns like water. So you say senza acqua (“without water”), not senza l’acqua.

Why do we say in giardino instead of nel giardino or a giardino?

In is the correct preposition for being inside or in a general location like a garden.
We drop the article when speaking of going to or being in places like casa, scuola, ufficio, giardino in a general sense. In giardino means “in the garden” (generally). If you meant a specific garden and wanted to stress it, you could say nel giardino.

Can I move in giardino to the beginning? How would that affect the sentence?

Yes. You can say In giardino i fiori appassiscono senza acqua for emphasis on location. Italian is flexible with word order, so moving circumstantial phrases like in giardino is fine. The core meaning stays the same.

What’s the difference between using senza and a conditional clause like se non (if not)?

Senza acqua means without water (an absence of something).
Se non hanno acqua would translate as if they don’t have water, introducing a condition rather than stating an absolute lack. Both convey a similar idea, but senza is more concise.

Why isn’t a subject pronoun like essi or loro used before appassiscono?

Italian often omits subject pronouns because the verb ending already indicates person and number. Since I fiori is present, there’s no need to repeat it with essi or loro; it would sound redundant.

Is there a difference between appassire, avvizzire, and sfiorire?

Yes:

Appassire: to wilt or wither (general loss of freshness, especially flowers and leaves).
Avvizzire: to shrivel or wilt (often implies a drier, more extreme shriveling).
Sfiorire: to fade (the bloom falls off or the color fades, less about wilting).

Can appassire take a direct object, or is it strictly intransitive?

It’s strictly intransitive. The flowers wilt themselves; nothing acts upon them as a direct object. If you wanted to express “to cause something to wilt,” you’d use far appassire (e.g., Quel caldo fa appassire i fiori).