Gardner plays for NSW Breakers in Women's National Cricket League and they will start their campaign against Queensland on September 21 without her. She will miss their match against Tasmania on September 23 as well.
Australia will play a warm-up match next Thursday against CA XI in Manly before their three-match T20I series against the White Ferns at North Sydney Oval from September 29.
Australia squad announced for the New Zealand series
Kate Mahony, the Physiotherapist of Australia, said, "Ashleigh has had ongoing concussion symptoms since being struck on the helmet last week. She is therefore unavailable for the WNCL fixture over the weekend. We will continue to monitor her progress as she recovers."
Full Fixtures here