Learn Hardcore Finnish: Mitä useammin karsimme omenapuuta, sitä vahvemmaksi sato kasvaa. - The more often we prune the apple tree, the stronger the harvest grows.

Mitä enemmän luet, sitä paremmin opit.
The more you read, the better you learn.
Mitä vähemmän nukun, sitä väsyneempi olen.
The less I sleep, the more tired I am.

Why is mitä used at the start? Isn’t mitä normally “what”?

Yes, mitä is the partitive form of mikä (“what / which”), but in this construction it behaves more like a special comparative marker, not a direct question word.

In Mitä useammin … sitä vahvemmaksi …:

mitä doesn’t mean “what” here; it’s part of the correlative pattern mitä X, sitä Y = “the X-er, the Y-er.”
It always appears with sitä (partitive of se) in the second clause.

So, you should think of mitä … sitä … as one fixed comparative structure rather than as “what … that …”.

What tense and person is karsimme, and why is there no me (“we”)?

Karsimme is 1st person plural (we) of karsia (“to prune”):

Present:
- minä karsin – I prune
- sinä karsit – you prune
- hän karsii – he/she prunes
- me karsimme – we prune
- te karsitte – you (pl.) prune
- he karsivat – they prune
Past (simple past) has the same 1st and 2nd person forms for this verb type:
- me karsimme – we pruned

So karsimme can mean “we prune” or “we pruned”. Finnish often uses the present to state general truths or regular patterns, so here it is best understood as:

“The more often we prune the apple tree, the stronger the crop grows.”

The pronoun me (“we”) is optional, because the personal ending -mme already shows the subject. Adding me would just add emphasis:

Mitä useammin me karsimme omenapuuta…
The more often we (as opposed to others) prune the apple tree…

Why is omenapuuta in the partitive case instead of omenapuu or omenapuun?

Omenapuuta is the partitive singular of omenapuu (“apple tree”).

Finnish uses the partitive object in several situations. Two relevant ones here:

Incomplete / partial action
Pruning doesn’t affect the whole tree in the sense of consuming or finishing it; you cut parts of it. That often calls for the partitive.
Repeated or ongoing action
The sentence talks about something that happens repeatedly (“the more often we prune”), not one single, clearly bounded event. Repeated/habitual actions commonly take the partitive object.

So:

karsia omenapuuta – to prune an apple tree (pruning it, parts of it, from time to time)
If you used omenapuun (genitive), it would sound more like a single, totalized event:
- Karsimme omenapuun eilen. – We pruned the apple tree yesterday. (one specific event, tree treated as a whole)

In this proverb-like generic sentence, partitive (omenapuuta) fits better.

Could you say omenapuun instead of omenapuuta here? How would it change the nuance?

You could say Mitä useammin karsimme omenapuun, sitä…, but the nuance changes:

omenapuuta (partitive)
– Emphasizes pruning as a repeated, ongoing, or partial action: we keep pruning parts of the tree.
omenapuun (genitive total object)
– Sounds more like each pruning event is a complete, bounded action: each time we prune “the whole tree” (from start to finish of that session).

In everyday speech, you’d still mostly hear omenapuuta in this kind of general statement about a repeated process.

What exactly is useammin, and how is it formed?

Useammin is the comparative adverb of usein (“often”).

Positive adverb: usein – often
Comparative adverb: useammin – more often
Superlative adverb: useimmin – most often

So:

Mitä useammin… – The more often…
Similar patterns:
- nopeasti → nopeammin – quickly → more quickly
- aikaisin → aikaisemmin – early → earlier

Why is it sitä vahvemmaksi, not just sitä vahvempi?

Vahvemmaksi is the translative case (-ksi), which often expresses a change of state: becoming something, turning into something.

vahva – strong
vahvempi – stronger (comparative)
vahvemmaksi – to a stronger (state)

In sitä vahvemmaksi sato kasvaa:

kasvaa = to grow
sato kasvaa vahvemmaksi = the crop grows to be stronger / into a stronger state

If you said sitä vahvempi sato on, it would describe a static property (“the crop is stronger”), whereas vahvemmaksi with kasvaa emphasizes development / change:

The more often we prune, the more the crop develops into a stronger one.

What does sato mean here, and what is its role in the sentence?

Sato means “harvest, yield, crop” – the amount of fruit produced.

In this sentence:

sato is in the nominative singular and is the subject of the verb kasvaa.
The structure is:
- (Se) sato kasvaa (sitä) vahvemmaksi.
  The crop grows (to be) stronger.

So sato is what is doing the growing, and vahvemmaksi describes the resulting state of that subject.

Why is the order sitä vahvemmaksi sato kasvaa? Could I say Sato kasvaa sitä vahvemmaksi instead?

Yes, both orders are grammatically correct:

Sitä vahvemmaksi sato kasvaa.
Sato kasvaa sitä vahvemmaksi.

Finnish word order is relatively flexible, and moving words mainly affects emphasis and information structure.

Sitä vahvemmaksi sato kasvaa puts sitä vahvemmaksi (the degree of strength) toward the front, highlighting the result state.
Sato kasvaa sitä vahvemmaksi puts sato up front, emphasizing the crop itself more.

In the original, the fronted sitä vahvemmaksi ties tightly to mitä useammin and makes the correlative mitä … sitä … pattern visually clear:

Mitä useammin …, sitä vahvemmaksi …

Why is there a comma in the middle of the sentence?

The sentence has two clauses forming the correlative structure:

Mitä useammin karsimme omenapuuta
sitä vahvemmaksi sato kasvaa

Each clause has its own verb (karsimme, kasvaa), so they are separate clauses. Finnish normally separates such clauses with a comma, especially in this mitä … sitä … pattern.

So the comma marks the boundary between the two linked clauses:

Mitä X, sitä Y
= The more X, the more Y.

Could I say Mitä useammin karsimme omenapuuta, sitä enemmän sato kasvaa instead? What would change?

Yes, that sentence is also grammatical and natural:

Mitä useammin karsimme omenapuuta, sitä enemmän sato kasvaa.
= The more often we prune the apple tree, the more the crop increases.

Nuance difference:

sitä vahvemmaksi sato kasvaa
– Focus on the quality/strength of the crop (e.g. healthier, more robust).
sitä enemmän sato kasvaa
– Focus on the quantity of the crop (e.g. number or amount of apples).

Both use the same mitä … sitä … pattern, but with different comparative ideas.

Is kasvaa always intransitive like this (“grow”), or can it be used transitively (“grow something”)?

In this sentence, kasvaa is intransitive: it describes the subject sato growing by itself.

Sato kasvaa. – The crop grows.

To express “to grow something” (transitive), Finnish usually uses kasvattaa:

Karsimme omenapuuta, jotta kasvatamme vahvemman sadon.
We prune the apple tree so that we grow a stronger crop.

So here, kasvaa is correctly intransitive, and the apple tree pruning is just the condition that influences how the crop itself grows.