Illalla puutarhan valaistus sytytetään automaattisesti, kun tulee hämärä.

In the evening the garden lighting is switched on automatically when it gets dim.

Breakdown of Illalla puutarhan valaistus sytytetään automaattisesti, kun tulee hämärä.

• kun: when
• tulla: to become
• illalla: in the evening
• hämärä: dim
• puutarha: the garden
• valaistus: the lighting
• sytyttää: to switch on
• automaattisesti: automatically

Questions & Answers about Illalla puutarhan valaistus sytytetään automaattisesti, kun tulee hämärä.

What does illalla mean literally, and why does it end in -lla?

Ilta means evening. The form illalla is ilta in the adessive case (ending -lla/-llä).

The adessive often means “on/at” in place and time expressions. With times of day, Finnish commonly uses adessive:

• illalla = in the evening / at nightfall
• aamulla = in the morning (from aamu)
• päivällä = in the daytime (from päivä)

So illalla puutarhan valaistus sytytetään… = In the evening, the garden lighting is turned on…

What case is puutarhan, and what does the structure puutarhan valaistus mean grammatically?

Puutarhan is the genitive singular of puutarha (garden).

Genitive + noun is a very common way to express “X’s Y” / “the Y of X”:

• puutarhan valaistus = the garden’s lighting / the lighting of the garden
• talon ovi = the door of the house / the house’s door
• lapsen lelu = the child’s toy

So grammatically, puutarhan valaistus is a normal noun phrase made of:

• puutarhan (whose?) → of the garden
• valaistus (what?) → lighting

Together: the garden lighting or the lighting of the garden.

Why is valaistus used instead of something meaning just “lights,” like valot?

Finnish distinguishes between:

• valaistus = lighting, illumination (the whole lighting system or arrangement)
• valot = lights (individual lamps or bulbs, often physically: the lights themselves)

In this sentence, puutarhan valaistus suggests the lighting setup of the garden – the system that turns on automatically – not just some individual lamps.

You could say puutarhan valot sytytetään automaattisesti, which would sound more like “the lights in the garden are turned on automatically” (focusing on the lamps themselves). Valaistus is a bit more technical or system-like.

What form is sytytetään, and how does the Finnish passive work here?

Sytytetään is:

• the present tense passive form of the verb sytyttää = to light / to switch on (a light, fire, etc.)

Finnish “passive” is more like an impersonal form:
it describes an action without saying who does it:

• valo sytytetään = the light is turned on / they turn on the light / one turns on the light

In your sentence:

• puutarhan valaistus sytytetään automaattisesti
  = the garden lighting is turned on automatically

There is no stated agent (no “by the system” etc.). The passive just says that the action happens, which is very natural in Finnish, especially for:

• general statements
• rules and instructions
• processes that “just happen” from the speaker’s point of view

Could you also say Illalla puutarhan valaistus syttyy automaattisesti? What’s the difference between sytytetään and syttyy?

Yes, that sentence is also grammatically correct, but there is a nuance.

• sytyttää = to light / to switch on (something) → sytytetään = is switched on (someone/something causes it)
• syttyä = to light up / to go on / to catch fire by itself → syttyy = goes on (intransitive)

So:

• valaistus sytytetään automaattisesti
  = the lighting is turned on automatically
  (there is some automatic system/agent that turns it on)

• valaistus syttyy automaattisesti
  = the lighting comes on automatically
  (the lighting itself “comes on” automatically)

Both work with automaattisesti, and in everyday speech both would be understood almost the same.

Grammatically, the original sytytetään keeps the idea that some mechanism is doing the switching on (even if it is not named).

What kind of word is automaattisesti, and how is it formed?

Automaattisesti is an adverb meaning automatically.

It is formed from the adjective automaattinen (automatic):

• automaattinen → automaattisesti

The ending -sti is a common way to form adverbs from adjectives:

• nopea (fast) → nopeasti (quickly)
• hidas (slow) → hitaasti (slowly)
• varma (sure) → varmasti (surely / certainly)

So sytytetään automaattisesti = is turned on automatically.

Why is there a comma before kun?

Kun introduces a subordinate clause (a “when”-clause):

• Illalla puutarhan valaistus sytytetään automaattisesti = main clause
• kun tulee hämärä = subordinate clause (when it gets dark)

In standard written Finnish, a comma is used before most subordinate clauses, including those starting with kun:

• Lähden kotiin, kun työpäivä päättyy.
  I’ll go home when the workday ends.

So the comma before kun is just following the normal punctuation rule for main clause + kun-clause.

What does kun tulee hämärä literally mean, and why is tulee used instead of on?

Literally, kun tulee hämärä is:

• kun = when
• tulee = comes (from tulla, to come)
• hämärä = dusk / dimness / twilight

So literally: “when dusk comes”, which in natural English is “when it gets dark / when it gets dim”.

Tulla (to come) is very often used in Finnish for change of state:

• tulla iloiseksi = to become happy
• tulla vanhaksi = to become old
• tulee kylmä = it gets cold

Here tulee hämärä describes the process of it becoming dim/dark, not the state of being dark.
If you used on, you would describe a state:

• kun on hämärää = when it is dark/dim (already)

So:

• kun tulee hämärä → when it gets dark (focus on the change, the onset of darkness)
• kun on hämärää → when it is dark (focus on the existing condition)

Why is hämärä in the basic (nominative) form here, and not the partitive hämärää?

With tulla (to become / to come to be), the new state is normally in the nominative:

• Hänestä tuli opettaja. = He/She became a teacher.
• Syksyllä tulee kylmä. = In autumn, it gets cold.
• Tulee kevät. = Spring is coming.

Here, tulee hämärä treats hämärä (dusk/dimness) as a “new state” that arrives, so nominative is natural.

The partitive hämärää is more typical with olla (to be) for a somewhat vague, uncountable state:

• Ulkona on hämärää. = It is dim/dusky outside.

So:

• tulee hämärä → dusk comes / it gets dark (new state, nominative)
• on hämärää → it is dim/dusky (ongoing, unbounded state, partitive)

Where is the English dummy subject “it” in the part “when it gets dark”? Why is there no se?

Finnish generally does not use a dummy subject like English “it” in weather/time/light expressions.

English:

• It gets dark.
• It rains.
• It is cold.

Finnish:

• Tulee hämärä. → It gets dark. (literally: comes dusk)
• Sataa. → It rains.
• On kylmä. → It is cold.

There is no se (it) because Finnish doesn’t need an empty, grammatical subject here.
The sentence kun tulee hämärä is complete without any pronoun; tulee just has no concrete subject (like English rains in it rains is really the important part).

Can illalla also mean “every evening”? How would you say that if you wanted to emphasize repetition?

Illalla by itself usually refers to a specific evening or “in the evening” in general, and context decides whether it’s about a one-time event or a habitual action.

In your sentence, because of the passive and automaattisesti, it naturally feels like a habitual rule: this is what happens whenever it gets dark in the evening.

To strongly emphasize repetition / every evening, Finnish prefers other forms:

• iltaisin = in the evenings / every evening
  
  • Iltaisin puutarhan valaistus sytytetään automaattisesti, kun tulee hämärä.
    = In the evenings, the garden lighting is turned on automatically when it gets dark.

So:

• illalla – in the evening (often understood as “in the evenings” when talking about a routine)
• iltaisin – explicitly in the evenings / every evening (habitual)