S. R. Faruqi:

The simile is new, and was so much to Mir's taste that he kept on using it throughout his life. From the second divan [{783,7}]:

yūñ bār-e gul se ab ke jhuke haiñ nihāl-e bāġh
jhuk jhuk ke jaise karte hoñ do chār yār bāt

[from the weight of the roses, nowadays the plants of the garden have bent in such a way,
the way, repeatedly bending, three or four friends would talk]

From the third divan [{1199,3}]:

ham bhī to faṣl-e gul meñ chal to ṭuk pās baiṭheñ
sar joṛ joṛ kaisī kalyāñ nikaltiyāñ haiñ

[let's us too, in the rose season, go and sit together for a bit
repeatedly bringing their heads close, how the buds emerge!]

From the sixth divan [{1865,5}]:

bahār āʾī gul phūl sar joṛe nikle
raheñ bāġh meñ kāsh us rang ham tū

[spring came, roses and flowers emerged with their heads together,
if only you and I would remain in the garden in that style/manner!]

With regard to meaning, the verse from the third divan appears to be the best; but in its expression there's not as much clarity as there is in the present verse. In niklī haiñ ab ke kalyāñ there's also an implication of the turmoil of the spring-- that is, in the spring it's not every time that there's such thickness and abundance of the buds.

[See also {1507,1}.]

FWP:

SETS
MOTIFS
NAMES
TERMS == SIMILE

It truly is a lovely image, isn't it? The densely growing roses swaying their heads toward each other in the breeze, and then away again, only to converge once more. The casual, careless, swaying movement is a large part of the charm. Good friends are relaxed when they sit together, they change their positions with informal ease; they often bring their heads together to exchange confidences; then their heads often sway back again as the friends are overtaken by laughter or surprise at some shared bit of gossip.

Note for grammar fans: In the first line ab ke modifies a colloquially omitted vaqt (or mausam ?).

Note for meter fans: 'Buds' is of course kaliyāñ , short-short-long, but for scansion purposes it here has to be read as kalyāñ , long-long; this is a permissible variation.