Learn German: Frischer Lavendel riecht sehr gut. - Fresh lavender smells very good.

Because there is no article (like der or ein) before the noun to show its gender and case. This is called strong declension. Lavendel is the subject of the sentence (nominative case) and it is masculine. So, the adjective frisch steps up and takes the masculine nominative ending -er to show us that.

Why is there no article before frischer Lavendel?

In German, just like in English, we often drop the article when talking about uncountable things, materials, or general categories. Here, we are talking about fresh lavender in general, not one specific lavender plant, so we use the zero article (no article at all).

Does the -er ending on frischer mean that Lavendel is a masculine noun?

Exactly! It is der Lavendel. Since there is no article used here, looking at the strong adjective ending is a great trick to figure out a noun's gender. The -er on the adjective tells you it is a masculine noun in the nominative case.

Is the verb riechen related to the English word "reek"? Does it mean it smells bad?