It depends on the variety. Some varieties take 90 days to produce fruit from seed, others take 120 days. Bloom is also influenced by the amount of water/food/sunlight the plant receives. Also, it's a curcubit, so it has male and female flowers. Male flowers tend to form first and these do not produce.
12 years
eight hours
~4 months
the bees that get the pollen produce it all back but not all they take and thats how flowers die
If planted from seeds, it can take several decades for the plant to produce flowers (it depends on too many factors to give a definite answer). After that, flowers are an annual occurrence. If you want a plant to produce flowers, buy on from a greenhouse that already has produced flowers.
1 year
two to three days
Forget me nots take about a dozen days to germinate. The first year it grows leaves and the second year it will produce flowers.
2 days
It is different for flowers you want to breed. To get a blue, black or purple flower, it'll take about a week or so. For pink flowers, they'll probably take a day or two.
Flowers take time to grow. If your monster's happiness is 999 then the flowers will grow fast (about 3 to 5 hours) but if you have a sad monster the flowers will take longer to grow.
The watermelon is larger and it will take more time for it to warm to the temperature around it.