Learn Hardcore Finnish: Kukkapenkki talon edessä on vielä tyhjä, mutta pian siihen istutetaan värikkäitä kukkia. - The flower bed in front of the house is still empty, but soon colourful flowers will be planted in it.

Writing it as kukka penkki would sound like you are talking about “a flower and a bench” as two separate things. Because “flowerbed” is one unit of meaning, Finnish makes it one word: kukkapenkki.

You’ll see this pattern everywhere:

kirjahylly (kirja + hylly) = bookshelf
puhelinlasku (puhelin + lasku) = phone bill

What case is talon in talon edessä, and what does it do?

Talon is the genitive singular of talo (house).

Pattern:
[GENITIVE] + [postposition] = “in front of X / behind X / near X”, etc.

talo (house) → talon (of the house)
edessä = “in front” (literally “at the front”)

So talon edessä literally means “at the front of the house” → “in front of the house”.

Other similar patterns:

talon takana = behind the house
talon vieressä = next to the house
talon lähellä = near the house

What’s the difference between edessä and eteen?

Both are related to “in front”, but they express different types of location:

edessä = static location: in front of (where something is)
- Auto on talon edessä. = The car is in front of the house.
eteen = direction / movement: to the front of (where something is moving)
- Auto ajetaan talon eteen. = The car is driven to the front of the house.

In your sentence, the flowerbed is already located in front of the house, so Finnish uses the static form edessä, not eteen.

Why is it tyhjä and not tyhjää after on?

Tyhjä is the nominative form of the adjective “empty”.

With olla (to be), when you describe a specific, countable subject, the predicate adjective is normally in the nominative, agreeing with the subject:

Kukkapenkki on tyhjä. = The flowerbed is empty.
Kukat ovat kauniita. = The flowers are beautiful. (plural nominative/partitive agreement pattern)

Tyhjää is the partitive form. It can appear with on in different structures, for example:

Siellä on tyhjää. = There is emptiness / it’s empty there (more abstract, not a specific, countable thing).

Here, kukkapenkki is a clear, concrete subject, so the normal descriptive structure is:
Kukkapenkki … on … tyhjä (nominative).

What exactly does vielä do in on vielä tyhjä?

Vielä here means “still” or “(as of now) yet”.

on tyhjä = is empty
on vielä tyhjä = is still empty (it hasn’t changed yet)

It adds the idea that the situation is temporary and expected to change, which the second clause confirms: soon colorful flowers will be planted there.

In negative sentences, vielä often corresponds to English “yet”:

Siihen ei ole vielä istutettu kukkia. = Flowers haven’t been planted there yet.

What does siihen refer to, and why this particular form?

Siihen is the illative form of the demonstrative pronoun se (“it / that”).

se = it / that
siinä = in/on it, there (static location)
siihen = into/onto it, there (direction, movement toward)

In the sentence, siihen refers back to kukkapenkki. It basically stands in for kukkapenkkiin:

…mutta pian kukkapenkkiin istutetaan värikkäitä kukkia.
…mutta pian siihen istutetaan värikkäitä kukkia.

Using siihen instead of repeating kukkapenkkiin sounds more natural and avoids repetition. It also emphasizes the destination of the action: the flowers will be planted into that bed.

What form is istutetaan, and why is that form used?

Istutetaan is the present tense passive (also often called the “impersonal”) of istuttaa (“to plant”).

stem: istuta-
passive ending: -taan / -tään
istutetaan ≈ “is planted / will be planted / people plant / they plant”

It’s used when:

The doer is unknown, unimportant, or general:
- Pian siihen istutetaan värikkäitä kukkia.
  ≈ Soon (they / people / someone) will plant colorful flowers there.

If you wanted to specify who is planting, you’d use a personal form instead:

Me istutamme siihen värikkäitä kukkia. = We will plant colorful flowers there.

Why are both värikkäitä and kukkia in the partitive plural?

Both words describe flowers as an indefinite quantity, so they take the partitive plural.

kukka → kukkia (partitive plural)
värikäs (colorful) → värikkäitä (partitive plural)

Reasons:

Indefinite amount / “some”
You’re not talking about a specific, counted group (like “the ten flowers”), but about some, unspecified number of flowers. Finnish uses the partitive for this kind of object.
Agreement
Adjectives agree in case and number with the noun they describe:
- värikkäitä kukkia = colorful (partitive plural) + flowers (partitive plural)

So värikkäitä kukkia corresponds quite closely to English “some colorful flowers”.

What’s the difference between värikkäitä kukkia and värikkäät kukat?

Both can mean “colorful flowers”, but the nuance and grammar differ:

värikkäitä kukkia
- partitive plural
- suggests an indefinite amount: some colorful flowers
- fits well with “we’ll (just) plant some colorful flowers there”, not a known set.
värikkäät kukat
- nominative plural
- usually implies a specific or total group of colorful flowers:
  - “the colorful flowers” or “all the colorful flowers”
- Pian siihen istutetaan värikkäät kukat would sound like you have a specific, known set of colorful flowers in mind and you’re planting that entire set.

In this context, the speaker talks about filling the empty bed with some colorful flowers in general, so värikkäitä kukkia is the natural choice.

How flexible is the word order here? Could parts of the sentence be moved?

Finnish word order is more flexible than English, but changes in order change emphasis.

Original:
Kukkapenkki talon edessä on vielä tyhjä, mutta pian siihen istutetaan värikkäitä kukkia.

Some natural variants (all grammatical, but with slightly different focus):

Talon edessä oleva kukkapenkki on vielä tyhjä, mutta pian siihen istutetaan värikkäitä kukkia.
- Adds oleva (“being”), making the relative clause explicit: the flowerbed that is in front of the house.
Kukkapenkki talon edessä on vielä tyhjä, mutta värikkäitä kukkia istutetaan siihen pian.
- Puts värikkäitä kukkia earlier → more emphasis on what will be planted.
Kukkapenkki talon edessä on vielä tyhjä, mutta pian värikkäitä kukkia istutetaan siihen.
- Starts the second clause with pian → emphasizes the time (“soon”).

The original order is neutral and clear:

Where and what (flowerbed in front of the house)
Current state (still empty)
Future change (soon, flowers will be planted there).

Could I say Pian istutamme siihen värikkäitä kukkia instead of the passive?

Yes, but it changes the point of view:

Pian siihen istutetaan värikkäitä kukkia.
- passive → the doer is not specified
- neutral, descriptive: “Soon (they / someone) will plant colorful flowers there.”
Pian istutamme siihen värikkäitä kukkia.
- me-form (1st person plural) → “we will plant”
- explicitly says we are the ones doing the planting.

Use the passive when you:

Don’t care who does it
Want a general statement (like in news, instructions, descriptions)

Use istutamme (or another personal form) when you want to highlight the subject/doer.