Hi, I'm Japanese and I can write some literal translations but to translate the title of books, poetries, movies, songs, etc isn't easy and there can be changed completly, please remember that in advance. 

My Heart Wants to Bloom. 

--> わたしのこころはさきたいです。(Watashi no kokoro wa sakitai desu.) 

However, I would llike to change a bit: 

わたしのこころははなをさかせたいです。(Watashi no kokoro wa hana wo sakasetai desu.)

わたしのこころははなひらきたいです。(Watashi no kokoro wa hanahirakitai desu.) 

I hope this was helpful. 

咲く seems to be primarily used for flowers/plant buds...

i'm wondering if in this case you could use 開く（ひらく）.

it's quite tricky conveying literal translations from two differently wired languages, especially when it comes to book and film titles.

Just guessing from my low japanese level, but I would try

私の心は咲きたいです。

watashi no kokoro wa sakitai desu.

someone can correct me please

Feel free to ask me. 

In this case, I translated "to bloom" はなをさかせる and はなひらく. 

The literal translation would be: 

はな を さかせる = make flowers bloom 

はなひらく is like はな が ひらく = flowers bloom 

*They aren't the same grammatically. 

If you say "fliwers bloom", you can translate literally, はな が さく. However, "the heart blooms" doesn't sound natural if I translate it literally so I add a bit more like "the heart blooms (like flowers bloom)".

I think "to bloom" is generally used with the word "flower(s)" in Japanese. 

Ex.) Spring is the season of blooming. 

The literal translation is: 春は咲く季節です[はる は さく きせつ です]。

To nake it more natural in Japanese, we should add a bit more. 

春は花[はな]が咲く季節です or 春は花開く[はなひらく]季節です。

I hope you get it but if you have still doubt, please keep asking. 

Thank you all so much!! I really, <em>really</em> really appreicate your help. :) 

@Ryoko, I hope you don't mind me asking, but what is the difference between the second and third translations? I know the first one has をさかせ and the second one has ひらき, but what's the difference? :?