Disable gradient in 3D scatter plot (lines) in R

I have some data, where height of different variables is displayed over 12 months, and most importantly the colour for each month is set in the ‘colour’ column within the dataframe, and is independent on any other variable.

My question is - is it possible to disable the autogradient in this type of graph? Right now every colour blends into another one (as you see in the example) - what I need is for it to end right in between any two months.

So, in the above example, I’d like for yellow to start just beween July and August, and end just as abruptly between August and September. Same for all other months. Is it possible do do this at all?

The script goes something like this:

months <- c("June", "July", "August", "September")
a <- c("t", "t", "t", "t")
height <- c("10", "12", "14", "20")
colour <- c("#7F7F7F", "#E36C09", "#FFFF00", "#E36C09")

dummydata <- data.frame(a, months, height, colour)
plot_ly(data = dummydata, x = ~months, y = ~height, z= ~a, split = ~trees,
        type = 'scatter3d', mode = 'lines', 
        line = list(color = dummydata$colour, width = 10)) %>%
    title = "some title",      
    scene = list(
      xaxis = list(title = " ", dtick = 1),    
      yaxis = list(title = "height, cm"),     
      zaxis = list(title = " ")