Nektaria’s name day is November 9, the feast of Nektarios of Aegina.
Churches that follow the Old (Julian) Calendar keep the same feast on November 22 of the civil calendar. See everything commemorated on November 9.
The saint behind the name

Nektarios of Aegina
November 9, Hierarch, Νεκτάριος
St. Nektarios of Aegina, Metropolitan of Pentapolis, is one of the most beloved saints of modern Greece. Born in Selybria of Thrace in 1846, he served the Church with great humility and was slandered and unjustly removed from his see in Egypt, bearing the injustice without bitterness. He later taught in Athens and founded the Holy Trinity Convent on the island of Aegina, where he reposed in 1920.
Also celebrating on November 9
These names share the feast, many of them other forms of the same name:
Nektarios, Nectarios, Nectarius
What to say on a name day
The Greek wish is Χρόνια Πολλά (Chronia Polla), “many years.” A call or a short message on the day is what people remember. See name day wishes you can send and what a name day is.