We are talking about water-soaked seeds.
Moisture is usually a stimulus for germination. Oops.
Some seeds barely make it to a year.
Epiphytes need “phytes” (plants, usually big, tall ones) on which to grow. Takes time.
I know that. But I also know that a lot of seeds would have to be released from their fruit before they could germinate. The fruit would have had to, well, rot, first to release the seeds.
Not to mention that Noah likely had seeds with him in the food he stored on the ark. Not EVERY single species/kind/whatever or seed bearing plants needed to be able to survive the flood waters.