Shen Qingqiu waves off his thanks and sets about helping him, murmuring suggestions and using a discarded leaf imbued with spiritual energy to trim the flowers to different lengths so the heads don't crowd.¹ He tries not to take over entirely, though--this is Galahad's arrangement, not his.

¹ He's not going to notice this about himself, but he's quite good at this. He's got a good aesthetic sense and is a perfectionist about the details.