This is my first wedding cake excited  and nervous!  It's a simple  tiered round rustic cake that will be iced with butter cream, decorated with real flowers , and feeds 100 people.   what cake sizes  do I need? and how do I go about flowers ,does the bride the one who will provide them or do I have to get'em? It's going to be outdoor at the couple home (back yard ) if they are picking it up  should I have them refrigerate it until the event leave it boxed?  any tips or points will be helpful. Thanks in a advance .

Wilton chart would give you 100 with a 6", 9" and 12".  There have been a lot of threads about flowers, there are actually a lot of things to consider.  Use the search feature for that.

Hi abi78,  congrats on your 1st wedding cake.  Based on your questions, I'm assuming you are doing this for a friend/family member (?).  Have you done tiered cakes before?

As pastrybaglady said, head on over to Wilton for the cake sizes but don't forget to factor in if the bride wants to freeze the top tier.  

For the flowers, that is between you and the bride to decide.  Does she have a florist for the wedding?  Sometimes the florist will take care of it but you need to work those details out asap.  You do need to research what flowers are safe for a cake.

As far as refrigeration, that depends on the weather.  I would not want a client picking up a tiered buttercream cake and transporting it though.  A buttercream cake in an outdoor setting in the summer is a recipe for disaster, so we would need to know what the weather is like in your part of the world.

If you give us some more info maybe we can help ya out :)

For a good icing for use outside, I recommend my icing.  See this link for a real life 97 degree test done by a CC'er:  http://www.cakecentral.com/forum/t/686989/and-i-bow-to-the-masterindydebi/0#post_6873024 

recipe:  http://www.cakecentral.com/recipe/6992/indydebis-crisco-based-buttercream-icing 

Thank you all for answering my questions and thank you so much indydebi for the recipe. to Jinkies thank you ,, the cake  is not for a friend./family member .    I live in the suburb of Chicago area it's been unpredictable lately..looks like i'm gonna use Indiydebi 's recipe. I'm familiar with tiered cakes , ,  just not sure of layers,  what the standard number of layers in wedding cakes, I have seen 3 and 4 ? and since we are the topic  icing, just for future reference  what is your take on cream cheese frosting and having the cake to set on the table for more than a couple of hours? I don't feel comfortable to have   iced cake with cream cheese icing   and have  it set on the table for hours before consumption. very grateful for your input .   :) 

Hi abi78, typically for formal cakes you would have 4 layers cake and 3 layers of filling but that is not law.  Cream cheese icing is not safe to sit out especially in warm weather.  I know I've seen a shelf stable cream cheese recipe floating around here on this site.  Maybe someone will jump on and let us know what it is because I can't remember the name and I've never used it.

I'll see if I can find it for you.

Sorry, I can't find it but I'm sure someone else will jump on who's used it.  If you are working under cottage food laws, you probably can't use cream cheese anyway.  

@indydebi, can she flavor your buttercream with a cream cheese flavoring?

Yes, use any flavoring you want.  You can add in WITH the vanilla or sub out the vanilla and add another flavor.  

Thank you so much Ladies you are awesome! sorry to respond late.. However,the bride dropped the ball on me !  she asked for a  wedding cake with all the goodies just  one week before the event and I was willing to accommodate. Just wasn't happy with the Price.. which was an average in my area. Oh well good riddance! . on the bright side I have learned somethings new thanks to all of your help and your time...x