Flower Noun + 开 + 了
开 (kāi) as an adjective describes something that is open or, when used with flowers, in bloom. It conveys the sense of something unfolding or blossoming. For example, 花儿都开了 means "the flowers have all bloomed."
窗户开着呢,怪不得这么冷。
Chuānghù kāizhe ne, guàibùdé zhème lěng.
The window is open — no wonder it's so cold.
公园里的桃花都开了,我们去看看吧。
Gōngyuán lǐ de táohuā dōu kāi le, wǒmen qù kànkan ba.
The peach blossoms in the park are all blooming. Let's go see them.
门是开的,你直接进来就行。
Mén shì kāi de, nǐ zhíjiē jìnlái jiù xíng.
The door is open. Just come right in.