The plants will eventually dehydrate. You can place the plant tissue in water or other medium/solution that would support a longer lifetime of the plant and seal the cell with, say, Norland Adhesive 65 or 67 to mitigate evaporation.

When preparing your permanent slides, make sure to use glass coverslips of the right thickness for the confocal microscope you are planning to use.

If you are looking at fluorescence, it will eventually fade.  Make sure you use a good anti-fade mounting medium.  Also seal all edges with nail polish, as oxygen will deplete your fluorescence.  Finally keep them in the dark and at 4C, do not freeze!!!

Thank you all for reply.

Could you please also suggest me the protocol by which I can prepare the slides along with the ingredients and its composition. As I was looking for the same but its like so many options and I do not know which would be best for my samples

Thanks 

I found one anti fade medium having ingredients: 10X PBS; Glycerol; DMSO; n-propyl gaallate

but I do not know whether this anti-fade medium also work well with plant cells?

please help