Learn Hardcore German: Ich finde diese Blumen schön.

It’s accusative plural. Ich is the subject (nominative), finden is a transitive verb that takes a direct object, and diese Blumen is that object, so it’s in the accusative. In the plural, the demonstrative has the same form for nominative and accusative: diese.

Why is schön not schöne here?

Because schön is a predicative adjective (an object complement after a verb), and predicative adjectives are uninflected in German. Adjectives only take endings when they stand before a noun (attributive), e.g. diese schönen Blumen.

Does Ich finde mean “I think”?

Yes, in the sense of “I consider.” Ich finde diese Blumen schön = “I think/consider these flowers beautiful.” Use Ich denke, dass … for thoughts or propositions (e.g., ideas, facts): Ich denke, dass er kommt. You can also say Ich halte diese Blumen für schön (more formal/literary).

What’s the gender and plural of Blume?

Singular: die Blume (feminine)
Plural: die Blumen
Indefinite forms: eine Blume, keine Blumen. Many feminine nouns form the plural with -n/-en.

Why is it diese, not dieser/diesen/dieses?

Because it’s plural accusative. The forms of dies- you’ll most commonly need:

Masculine: nominative dieser, accusative diesen
Feminine: nominative/accusative diese
Neuter: nominative/accusative dieses
Plural (all genders): nominative/accusative diese

Where does nicht go to negate this?

General negation of the adjective: Ich finde diese Blumen nicht schön.
Contrastive focus on the object: Ich finde nicht diese Blumen schön, sondern jene dort.
“Nicht” comes right before what you’re negating (here: the adjective phrase or the noun phrase).

Is diese “this” or “these”? How do I say the other forms?

Diese here means “these.” The demonstrative dies- = “this/these”:

This (masc/fem/neut): dieser/diese/dieses
These (plural): diese For “that/those,” everyday German often uses der/die/das contextually; jener/jene/jenes exists but is rarer in speech.

Can I drop diese to talk about flowers in general?

Yes: Ich finde Blumen schön = “I find flowers beautiful (in general).” With diese, you mean specific flowers in the context: these flowers.

Are there other natural ways to say this?

Dative verb gefallen: Diese Blumen gefallen mir.
Verb of liking mögen: Ich mag diese Blumen.
Consider-construction: Ich halte diese Blumen für schön.
All are idiomatic; nuances differ slightly (aesthetic judgment vs. personal liking).

Can I change the word order for emphasis?

Yes, keeping the finite verb in second position:

Diese Blumen finde ich schön. (emphasis on the flowers)
Schön finde ich diese Blumen. (emphasis on “beautiful”)
Diese Blumen sind schön, finde ich. (comment tag at the end)

How can I intensify schön?

Ich finde diese Blumen sehr schön. (very)
… wirklich schön. (really)
… ziemlich schön. (quite)
… so schön! (so beautiful; often exclamatory or followed by a result: so schön, dass …)

How do I make comparative and superlative here?

Comparative: schöner → Ich finde diese Blumen schöner (als die anderen).
Superlative (predicative): am schönsten → Ich finde diese Blumen am schönsten.
Attributive superlative before nouns: die schönsten Blumen.

How is finden conjugated?

Present: ich finde, du findest, er/sie/es findet, wir finden, ihr findet, sie finden
Simple past: ich fand …
Perfect: ich habe … gefunden
Note the extra -e- in du findest to ease pronunciation.

Pronunciation tips for the sentence?

Ich: soft “ch” [ç], not like English “k.”
finde: short i [ɪ]; final e is a schwa [ə].
diese: ie = long [iː]; s between vowels sounds like [z].
Blumen: u is long [uː].
schön: sch = [ʃ]; ö is long [øː].

Why is Blumen capitalized but schön isn’t?

All nouns are capitalized in German, so Blumen is capitalized. Adjectives are not, so schön is lowercase. Ich is capitalized here because it begins the sentence (not because the pronoun itself is capitalized by rule).

When would I use diesen Blumen instead?

That’s dative plural, used after dative prepositions or in dative roles:

mit diesen Blumen (with these flowers)
zu diesen Blumen passt die Vase. (the vase matches these flowers)
Note: Dative plural nouns take an extra -n if possible; Blumen already ends in -n, so it stays Blumen.