As Maximillian says of his design 1584 the Koru represents new beginnings, life, peace, evolution, and strength. The Double Koru symbolizing the coming together between the indigenous people and the immigrants from Europe, also representing the two main islands of New Zealand.
However I don't think black is right for NZ.
Many seem fixated on black as the country's national colour. This originates from the All Blacks strip chosen in 1905 - a tribute to the lack of imagination of the rugby heirarchy of the time. Let the sports teams have their black.
As a country our flag should accentuate our clean colourful land, sea and sky.
Some say black is the colour of our night sky. Not so. Go out at night well away from urban light pollution and murky air and look up. The night sky is luminous with the sparkling of millions of stars - truly inspiring and definitely NOT BLACK.
Although black is a traditional colour in Maori art, it is also the colour of gloom, darkness, foreboding power, piracy and ISIS - let's avoid black. So I have changed the black to red, an earthy red as used in Maori design.