Jeg vanner mindre, ikke minst fordi hvileperioden har begynt.

Vanner is the present tense of å vanne, meaning to water.

So jeg vanner means I water / I am watering.

Norwegian often leaves out the object when it is obvious from context. In a sentence like this, the speaker is probably talking about watering plants, so plantene does not need to be stated.

A more explicit version would be:

Jeg vanner plantene mindre.

But the shorter version sounds completely natural if everyone already knows what is being watered.

Because mindre is used here as an adverb, modifying the verb vanner.

It means less in the sense of to a lesser degree / not as much:

• Jeg vanner mindre = I water less

Færre is used with countable plural nouns:

• færre planter = fewer plants
• færre dager = fewer days

So:

• mindre = less
• færre = fewer

It can suggest either, depending on context.

Jeg vanner mindre is a bit broad. It can mean:

• I water less often
• I give less water
• I water less in general

If you want to be more precise, Norwegian can say:

• Jeg vanner sjeldnere = I water less often
• Jeg gir plantene mindre vann = I give the plants less water

So mindre here is intentionally general.

Ikke minst literally means not least, but in natural English it often means:

• especially
• particularly
• not least because

In this sentence, it highlights the reason that follows as an important one:

• ikke minst fordi hvileperioden har begynt
  = especially because the rest/dormant period has begun

So it is adding emphasis, not negation in the ordinary sense.

Because fordi introduces a subordinate clause, and subordinate clauses normally do not use the main-clause V2 word order.

In a main clause, Norwegian often puts the verb in second position:

• Hvileperioden har begynt.

But after fordi, the normal order is:

• fordi hvileperioden har begynt

So the pattern is:

• fordi + subject + finite verb

This is very common in Norwegian after words like:

• fordi = because
• at = that
• når = when
• hvis = if

Har begynt is the present perfect of å begynne.

It is used because the sentence focuses on a past action with a present result:

• the rest period has started
• and that is why the speaker waters less now

Compare:

• har begynt = has begun / has started
• begynte = began / started
• begynner = begins / is beginning

So har begynt fits well because the beginning happened already, but it still matters in the present.

Because Norwegian normally writes compound nouns as a single word.

So:

• hvile = rest
• periode = period

Together they become:

• hvileperiode = rest period / dormant period

This is very typical in Norwegian. English often uses two words where Norwegian uses one:

• toothbrush / tannbørste
• summer holiday / sommerferie
• rest period / hvileperiode

For English speakers, this is one of the most important spelling habits to get used to.

The ending -en is the definite article attached to the noun.

So:

• en hvileperiode = a rest period
• hvileperioden = the rest period

Unlike English, Norwegian usually adds the definite article to the end of the noun instead of putting a separate word like the in front.

That means:

• periode = period
• perioden = the period

And in the full compound:

• hvileperiode = rest period
• hvileperioden = the rest period

It is mainly there to mark a pause and separate the extra explanation from the first part of the sentence.

The core statement is:

• Jeg vanner mindre

Then the speaker adds an emphasized reason:

• ikke minst fordi hvileperioden har begynt

In simpler fordi clauses, Norwegian often has no comma:

• Jeg vanner mindre fordi hvileperioden har begynt.

But in this sentence, the comma helps show that ikke minst fordi ... is an added, slightly parenthetical comment. So it is a style and clarity choice.

Yes. Norwegian allows that:

Ikke minst fordi hvileperioden har begynt, vanner jeg mindre.

Notice what happens in the main clause after the fronted phrase:

• vanner jeg
• not jeg vanner

That is because Norwegian main clauses follow the verb-second rule. When something other than the subject comes first, the verb usually comes before the subject.

So:

• Jeg vanner mindre.
• Derfor vanner jeg mindre.
• Ikke minst fordi hvileperioden har begynt, vanner jeg mindre.

Yes, absolutely.

It is a complete sentence with:

• subject: jeg
• verb: vanner
• adverb: mindre

Even though the object is omitted, the sentence is still natural and complete because the missing information is understood from context.

If you want to make it more specific, you could say:

• Jeg vanner plantene mindre.
• Jeg vanner mindre enn før.
• Jeg vanner sjeldnere nå.

But the original sentence is perfectly normal as it stands.