Grammar:
Pefect tense: We create the past tense (perfect) with the auxiliary verbs ?haben? (ich habe, du hast, er hat etc. ) and ?sein? (ich bin, du bist, er ist etc.), and with the participle of the verb (singen > gesungen etc.). The poet used the past tense in the first and the fourth stanza: Die Biene hat das Bett ausgewählt. Du hast den Frühling nicht gekannt.
Subjunctive: The narrator speaks to the ?Georgine? (old for Dahlie = dahlia), and conducts thought experiments in stanza two and three. To express a hypothetical thought in a sentence we have to turn the verb from the state of describing a real action to a state of ?what-if? (subjunctive). In German, the verb can take it's own form: Ich bin ein Poet (I am a poet) changes to ?ich wäre ein Poet? (I would be a poet). The ?sein? (infinitive) has turned into ?wären?.
Other verbs in the subjunctive state are in this poem are:
bringen (to bring) ? brächten (would bring)
benetzen (to sprinkle) ? benetzten (would sprinkle)
begießen (to water) ? begössen (would water)
Vocabulary:
das Rosenmärchen = fairy tale of roses, a theme in literature in which the rose is used as a metaphor for love.
honigsatt = (creation by the poet) full with honey 
der Schlummer = slumber
leben hin (hinleben) = here: to spend time
feuergelb =  (creation by the poet) glaring yellow
der Maitau = dew in may
das Junilicht = sunlight in June
locken = to allure, to entice
vergebens = in vain
dasselbe, derselbe = the same
das Entzücken = delight, enchantment

1. Warum so spät erst, Georgine?
Why so late, dahlia?
Das Rosenmärchen ist erzählt,
The fairy of roses has been told,
Und honigsatt hat sich die Biene
And the bee, full with honey,
Ihr Bett zum Schlummer ausgewählt.
Chose its bed for a slumber.

2. Sind nicht zu kalt dir diese Nächte?
Are the nights not too cold for you?
Wie lebst du diese Tage hin?
How do you spend these days?
Wenn ich dir jetzt den Frühling brächte,
If I brought springtime to you now,
Du feuergelbe Träumerin,
You glaring yellow dreamer,


3. Wenn ich mit Maitau dich benetzte,
If I sprinkled the dew of May on you,
Begösse dich mit Junilicht,
Watered you in the light of June,
Doch ach, dann wärst du nicht die Letzte,
But alas, then you would not be the last one,
Die stolze Einzige auch nicht.
Nor the proud only one.

4. Wie, Träum'rin, lock' ich vergebens?
Why, dreamer, am I alluring you in vain?
So reich' mir schwesterlich die Hand,
Well, then give me your hand sisterly,
Ich hab' den Maitag dieses Lebens
I have not known the may day of this life,
Wie du den Frühling nicht gekannt;
As you do not know the spring.

5. Und spät wie dir, du Feuergelbe,
And late to you, you glaring yellow one,
Stahl sich die Liebe mir ins Herz;
Love stole into my heart,
Ob spät, ob früh, es ist dasselbe
If late, if early, it is the same
Entzücken und derselbe Schmerz.
Delight and the same pain.

Translation and song facts provided by the Berlin-based writer and German tutor Bernd Hendricks whose book "Ach ich fühl's - German for Opera Singers in Three Acts: Studying, Speaking, Singing" can be purchased here: 
http://www.amazon.com/Ach-ich-f%C3%BChls-Studying-Speaking/dp/1312463457/ref=sr_1_1?ie=UTF8&qid=1413880914&sr=8-1&keywords=Ach+ich+f%C3%BChl%27s+German+for+Opera+Singers

And his blog accessed here: https://achichfuehls.wordpress.com/