Schedule E supplies or depreciation?

[Matt Maves]

I'm curious as to what is considered "supplies" or "cleaning and maintenance" and also if I need to depreciate.

Each year I purchase a lot of mulch and annual flowers for my rental.  I do all the work myself.  Would I put the price of this under supplies?  Or since it's not necessary to live, but just something pretty, can I still deduct it? 

Annuals die each year, but what if they are perennials, would those need to be depreciated over 15 years?

2 years ago I figured the number for the depreciation on my house,  I subtracted the land value and divided the number by 27.5.   I understand I will be using the same number each year. 

 What if I add things to my house that need to be depreciated after I made that initial calculation? for instance I built a fence and some pergolas last summer and I understand that is something that is depreciated over 15 years.  Do I just do the math myself and keep those records for myself where I divide the total cost by 15, and then add this number to my other number for the house depreciation and simply put that number on my schedule E?    Or do I need to send in a separate form further explaining where the numbers come from.

Thanks