Why many plants cant appear in my collection book??

@LoboMaltes 

Do you mean you don't see the plants in the Alamanac?

If you can't see the plants, these plants are probably seasonal plants which are only featured for a limited time. Jack O Lantern is one of the seasonal plants, and I believe its time on offer has been over. So unless you've bought it, you won't be able to see it until it is featured again in the future.

Also Jack O Lantern is a money premium plant, so you can't unlock it by just collecting enough seeds. You need to buy it with money.

Other examples of seasonal plants are Witch Hazel, Ghost Pepper, Hot Date, Holly Barrier, Strawburst, etc. Unless you've unlocked them using seed packets, gems, or money, you won't see them outside the certain duration when they're featured.

thanks so much. my focus is adquire  the ice bloom .    need buy too ? or i can unlock in events?

@LoboMaltes   There are special edition and seasonal plants which only appear in your almanac (book) during a set length of time, more information can be read from

https://plantsvszombies.fandom.com/wiki/Category:Special-edition_plants

EIDIT.  you can also read more about Ice bloom on  

https://plantsvszombies.fandom.com/wiki/Ice_Bloom