I guess it is a matter of personal preferences and the meaning of the sentence since both primavera and la primavera are correct. In some contexts you need the article and in others you don't.
Also, one sounds better than the other in some contexts.
See this sentence
I'll be traveling to Europe this spring = Viajaré a Europa esta primavera
There you can not use "la", but if we change the sentence to
I'll be traveling to Europe in [the] spring = Viajaré a Europa en (la) primavera
then you can use "la" if you prefer but it will be right either way.
In the following sentence you have to use "la"
I traveled to Europe last spring = Viajé a Europa la primavera pasada
In the following example it sounds better if you use "la".
I love spring = Me gusta la primavera
other example where both are ok is:
Plants bloom in [the] spring = Las plantas florecen en (la) primavera
So for a good translation you have to check the preposition used in English. For example if you have "this" you don't use "la", with "on" you could choose if you want to use "la" but with "last, next" you have to include "la". Prepositions are difficult in all languages but you get use to them as you hear them more and more.