The Kiznaiver site just posted the official flowers the girls are holding and confirmed their meaning will help us better understand the series.
Nico: Agapanthus395Please respect copyright.ＰＥＮＡＮＡK30N7mieXu
Honoka: Zinnia395Please respect copyright.ＰＥＮＡＮＡ0S0Ls1UpUm
Chidori: China aster395Please respect copyright.ＰＥＮＡＮＡoPTsOqqIX4
Noriko: Roses
So I did some Hana kotoba google’ ing. Here’s a brief (second) look at their meaning below the cut!
Nico
The Agapanthus is known as the “flower of love”. Its meanings include 「the arrival of (romantic) love (恋の訪れ)」, 「love letter（ラブレター）」 and 「intellectual attire/guise （知的な装い）」. It’s said that this last meaning comes from the refreshing and delicate appearance of the pale purple/blue flowers. 395Please respect copyright.ＰＥＮＡＮＡ7kxEfiF6An
Source: [x]
Honoka
「thoughts of absent friends（不在の友を思う）」395Please respect copyright.ＰＥＮＡＮＡWrinUzAzuB
「I mourn your absence（あなたの不在を悲しむ）」395Please respect copyright.ＰＥＮＡＮＡ6vzlYBCcOy
「Don't be off your guard (注意を怠るな)」395Please respect copyright.ＰＥＮＡＮＡcr1oo28IMt
Source: [x]
“Thoughts of friends or thoughts of a missing friend are the most common meanings for the zinnia.“ Yellow zinnias mean “daily remembrance”.395Please respect copyright.ＰＥＮＡＮＡJRTJyTnnsB
Source: [x]
Chidori
General meaning:395Please respect copyright.ＰＥＮＡＮＡV3VSpaLQK6
• 「Change (変化)」395Please respect copyright.ＰＥＮＡＮＡqZyomMiFwa
• 「Reminiscence (追憶)」395Please respect copyright.ＰＥＮＡＮＡYLSZtdD8eV
• 「Agreement / Sympathy (同感)」395Please respect copyright.ＰＥＮＡＮＡzCOjmKivaj
• 「Belief in (romantic) Love (信じる恋)」
Occidental meaning:395Please respect copyright.ＰＥＮＡＮＡm41zDG3nhs
• 「Variety（多様性、変化）」395Please respect copyright.ＰＥＮＡＮＡXWdoYtA9e8
• 「Fidelity（忠実、貞節）」395Please respect copyright.ＰＥＮＡＮＡV4FImZpkkX
• 「I will think of you（私はあなたを想うでしょう）」
Color meaning:395Please respect copyright.ＰＥＮＡＮＡwkptTMYcje
• White: 「Please believe me (私を信じてください)」395Please respect copyright.ＰＥＮＡＮＡFRRsqbwflM
• Purple: 「Victory of (romantic) love (恋の勝利)」, 「My love is deeper than yours (私の愛はあなたの愛より深い)」395Please respect copyright.ＰＥＮＡＮＡznG5gxMcwx
Source: [x]
Noriko
It’s hard to tell whether Noriko is holding orange roses or yellow ones, so I’m including both!
General meaning:395Please respect copyright.ＰＥＮＡＮＡ6QwCfIpLmp
• 「Love (愛)」395Please respect copyright.ＰＥＮＡＮＡbtf20jgSI7
• 「Beauty (美)」395Please respect copyright.ＰＥＮＡＮＡkh3kXOugw3
Source: [x]
Color meaning:395Please respect copyright.ＰＥＮＡＮＡZVw2xauFmn
• White: 「 Purity / Chastity( 純潔)」, 「I am worthy of you (私はあなたにふさわしい)」, 「Deep respect (深い尊敬)」
• Green: 「Calm / Gentle (穏やか)」, 「You can have hope (あなたは希望を持ちえる)」
• Orange: 「Innocence（無邪気）」, 「Bonds / Kizuna （絆）」, 「Healthy（健やか）」, 「Trust / Faith （信頼 ）」.
• Yellow: 「Decrease of love（愛情の薄らぎ）」, 「Jealousy （嫉妬）」, 「Friendship （友情）」, 「Devotion （ 献身 ）」, 「Tired / Weary of (romantic) love （恋に飽きた）」.395Please respect copyright.ＰＥＮＡＮＡv0yqGXlU5q
Source: [x] & [x]
and then Add to home screen.