Here's a better translation. As far as I can tell, the translator is not identified.
-Joe Offer-

FLOWER CAROL

1. Spring has now unwrapped the flowers,
   Day is fast reviving,
   Life in all her growing powers
   Towards the light is striving:
   Gone the iron touch of cold,
   Winter time and frost time,
   Seedlings, working through the mould,
   Now make up for lost time.
   
   
2. Herb and plant that, winter long,
   Slumbered at their leisure,
   Now bestirring, green and strong,
   Find in growth their pleasure:
   All the world with beauty fills,
   Gold the green enhancing;
   Flowers make glee among the hills,
   And set the meadows dancing.
   
   
3. Through each wonder of fair days
   God himself expresses;
   Beauty follows all his ways,
   As the world he blesses:
   So, as he renews the earth,
   Artist without rival,
   In his grace of glad new birth
   We must seek revival.
   
   
4. Earth puts on her dress of glee;
   Flowers and grasses hide her;
   We go forth in charity—
   Brothers all beside her;
   For, as man this glory sees
   In the awakening season,
   Reason learns the heart's decrees,
   And hearts are led by reason
   
   
5. Praise the Maker, all ye saints;
   He with glory girt you,
   He who skies and meadows paints
   Fashioned all your virtue;
   Praise him, seers, heroes, kings,
   Heralds of perfection;
   Brothers, praise him, for he brings
   All to resurrection!

This is a free translation, with a doxology, of the words proper to "Tempus Adest Floridum," (from Piae Cantiones, 1582) the spring carol which Neale turned into a Christmas carol by writing his rendering of the legend of "Good King Wenceslas."

Source: The Oxford Book of Carols, 1928, 1964

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Most of this has been posted elsewhere, but here is the entire text of the Oxford Book of Carols commentary on "Good King Wenceslas":

This rather confused narrative owes its popularity to the delightful tune, which is that of a Spring carol. 'Tempus adest floridum', No. 99. Unfortunately Neale in 1853 substituted for the Spring carol this 'Good King Wenceslas', one of his less happy pieces, which E. Duncan goes so far as to call 'doggerel', and Bullen condemns as 'poor and commonplace to the last degree'. The time has not yet come for a comprehensive book to discard it; but we reprint the tune in its proper setting ('Spring has now unwrapped the flowers'), not without hope that, with the present wealth of carols for Christmas, 'Good King Wenceslas' may gradually pass into disuse, and the tune be restored to spring-time. Neale did the same kind of thing to another Spring carol, In vernali tempore' (No. 98; cf. No. 102); but this was not popularized by Bramley & Stainer. Rather strongly worded, isn't it?

OK, now look at the commentary from The Shorter New Oxford Book of Carols (1993):
Wenceslas is the German form of Vaclav. Vaclav the Good reigned in Bohemia from 922 to 929, later becoming the Czech patron saint. Neale's carol is not based on any known incident in the saint's life: it is probably no more than a pious illustration of the virtue of charity—
Stephen's Day (Boxing Day, 26 December) is a traditional day for giving to the poor. The tune is that of a spring song from Piae Cantiones (1582).

Certainly milder, but also not excessively complimentary.

Some of the verses of "Flower Carol" appear in Quaker and Unitarian hymnals, and (as stated above) it's in the Rise Up Singing songbook. As for myself, I prefer "Good King Wenceslas." But then, I also like to eat at McDonald's.

-Joe Offer-