Io innaffio le piante in giardino ogni mattina.

In Italian, subject pronouns like Io (I) are usually optional because the verb ending already tells you who is doing the action. Here, innaffio clearly means “I water.” You include Io only for:

• Emphasis (e.g. Io innaffio, tu dormi!)
• Contrast (e.g. Io innaffio, ma lei non lo fa)
  Otherwise, you can simply say Innaffio le piante… and it’s perfectly natural.

Innaffio is the first-person singular present indicative of the verb innaffiare, which means to water (as in watering plants). Breaking it down:

• Verb: innaffiare
• Person/number: first-person singular (I)
• Tense/mood: present indicative (I water / I am watering)

Le is the feminine plural definite article (“the”) matching piante (plants), which is feminine plural. You use le piante when you mean the plants you’ve already mentioned or that are clear from context. If you say delle piante, you’re saying “some plants” (indefinite). That changes the meaning slightly:

• Innaffio le piante… “I water the plants…”
• Innaffio delle piante… “I water some plants…”

Place prepositions in Italian follow patterns:

• in giardino (in + no article) is the idiomatic way to say “in the garden.”
• nel giardino (in + il) is grammatically correct (“in the garden”), but sounds more formal or specific (e.g. “in the garden” as opposed to other gardens).
• a giardino is never used; a goes with locations like a casa, a scuola, a teatro, but in giardino is fixed.

Ogni mattina literally means every morning. You can also say:

• Tutte le mattine (all the mornings)
• Ogni giorno​ di mattina (every day in the morning) – less common
  Both convey the same habit of doing something each morning.

Yes. Italian is quite flexible with adverbial phrases:

• Ogni mattina innaffio le piante in giardino.
• In giardino ogni mattina innaffio le piante.
  All of these sound natural. Moving ogni mattina to the front simply emphasizes the time (“Every morning…”).

Italian doesn’t use a continuous/progressive form the way English does (I am watering). The simple present (innaffio) covers both:

• An action happening right now (“I’m watering the plants now.”)
• A habitual action (“I water the plants every morning.”)
  You wouldn’t say sto innaffiando for a routine; that form is only for actions in progress at the moment of speaking.