There are some questions about the Ruby Voucher feature in the game (Voucher Packs). Here's a small FAQ, hope it's helpful!

Click the shop and check the items which can buy with the vouchers

FAQ:

1. What can I buy with Vouchers?

ANY Ruby Tree of Flower unlock, even the Time Limited Ruby Trees needed for time limited events.

2. Is the Voucher worth the equivalent of 1 Ruby?

Yes.

3. Can I combine Rubies and Vouchers?

No (so you need at least 3 Vouchers in order to use them during this time's event.)

4. Will my Vouchers vanish into thin air after this event?

No. They will be kept so you are free to use them the next time we do this event (we plan to).

5. Where can I see the amount of Vouchers I currently have?

On the Voucher Pack panel (see screenshot).

Troubleshooting:

1. In my Shop, I see Ruby Trees but there's no Voucher icon. Why?

The Voucher icons will only appear after you bought 1 or more Vouchers.

2. I want to buy a Ruby Tree using Vouchers, but the game only lets me pay in Rubies.

Check if you have enough Vouchers for the tree (if the tree costs 8 Rubies, you need 8 Vouchers, otherwise the game will let you pay using Rubies).