Coriander is an uncountable noun and does not have a plural form.

[English]?k?ri?nd?(r) [US]?k?:ri?nd?(r) Uncountable

n. Plant coriander, coriander< /p>

[Example]Keep it spontaneous, make every flower occasion special - unless you 're giving someone coriander because that 's just not vase-worthy.

Let it take its course, make every flower occasion special - unless you 're giving someone coriander because that 's just not vase-worthy. Give flowers in a unique way, unless you are giving coriander to someone, because they are not worth putting in a vase.