How come nursery plants flower so early? | Ornamental gardening | Hydroponics farming in India

On my way to work I pass many nurseries and as the winter is setting in, I see many pots lined up in the front with flower blooming. I mean the pots are small containers, some only as deep as 5 inch ones, but still the plant growth in them is phenomenal.

I discussed this with Roxy from Garden Guru. As per him, that's not a right thing to do. He said these nurseries use a prohibited and banned chemical called Nitro Butasol or something, which actually forces the plant to bloom early. And this is wrong! It shouldn't be done. Coz soon after the blooms, the plant dooms. Is it so?

I have never bought these plants coz I grow my own (of course with very very slow growth rate and very few flowers per pot). Hence the temptation. What the magic potion they put?

Any clues? Would like to understand this concept more.