It's really just personal preference whether you use "cherry blossom" or "cherry blossom tree", just as you might say "the roses are starting to bloom" or "the rose bushes are starting to bloom". Your use of the ending -네요 indicates emotion which is a good addition, but you are still using the present tense. Present progressive would be 시잣하고 있다. But Koreans tend to use just the plain present instead of present progressive - it wouldn't be wrong, it's just not needed. One thing I've learned is that you want to avoid being too literal in translations. Korean requires that you think differently than English.