Morning glory plants on the ground floor not yielding flowers

Due to the fake dengue allegations, the domain investor removed all her plants from the terrace, most were shifted to the ground floor
It appears that some chemicals which are sprayed on the ground floor plants are adversely affecting the flowering of the morning glory plants.
A few seeds germinated on the first floor and terrace without any pot, yet these plants are having flowers though they are very small, less than three feet in some cases.
In contrast the plants from the ground floor are at least 10-20 feet in length, yet they are not yielding any flowers, though they are derived from almost the same seeds
Information on the reason for the non-flowering of the morning glory plant on the ground floor are appreciated, please send email to