Sharon kept cutting through the plants but still found nothing, she bapegan to suspect that Greta changed positions whenever she drew close to finding her. Greta had begun to pant heavily, keeping up her spell was taking a lot of both her energy and mental strength.
Her plants contained various poisons, some of which made her opponents delirious or knocked them out cold, for any of these to be very effective, contact had to be made and frezza had already warned Sharon. The poison spread by air but it was a much longer process, and she lacked the energy to sustain it for such amounts of time.
She had hoped to defeat frezza quickly and then follow through with Sharon, so she could help the triplets but he plan wasn't going as expected, frezza had only touched one of the weaker poisonous flowers and the effects were minimal at Best.