Error while deriving name of Month in R

Question

The following data shows my projects, time frames, and their phases. I would like to visualize this data using R ggplot() code shown below. However, as we can see below, getting an error while inferring Months from the data. I would like to use the name of Months as x-axis labels. Moreover, I need to print the name of the projects besides the rectangular boxes. Please help me in this. Thank you.

> temp
  projects     starts       ends order     Phase
      A 2013-02-15 2013-03-15     1  Research
      A 2013-03-16 2013-04-15     1 Prototype
      B 2013-04-07 2013-04-30     2  Research
     B 2013-05-01 2013-08-30     2 Prototype
      C 2013-05-01 2013-07-30     3  Research
      D 2013-05-01 2013-07-30     4  Research


> a = ggplot(temp, aes(xmin = starts, xmax = ends, ymin = order, ymax = order+0.5)) + geom_rect(aes(fill=Phase), color="black") + theme_bw()
> b = a + geom_text(aes(x= starts + (ends-starts)/2 ,y=order+0.25, label=projects)) 
> b
Error in unit(x, default.units) : 'x' and 'units' must have length > 0
In addition: Warning messages:
1: In Ops.factor(ends, starts) : - not meaningful for factors
2: In Ops.factor(starts, (ends - starts)/2) : + not meaningful for factors
3: Removed 6 rows containing missing values (geom_text). 

Please also see the version of R.

> version
               _                            
platform       i686-pc-linux-gnu            
arch           i686                         
os             linux-gnu                    
system         i686, linux-gnu              
status                                      
major          2                            
minor          15.2                         
year           2012                         
month          10                           
day            26                           
svn rev        61015                        
language       R                            
version.string R version 2.15.2 (2012-10-26)

Answer 1

try converting starts and ends to Date

 temp$starts <- as.Date(temp$starts)
 temp$ends   <- as.Date(temp$ends)

If that does not work, you may want to use dput(temp) and paste that into your question.

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Copying + Pasting OP's data, converting to date, then using OP's code