Under normal growing conditions, should last long enough.
-however-
If you're growing indoors, you've already flunked the "I'd rather just let nature do it" test.
From light cycles, to nutrients...adaptation and manipulation is what an indoor grow is all about.
Painting the pollen on the lower branches allows you to generate hundreds of seeds, while still harvesting seedless buds from those you didn't pollinate. You can even harvest the mature seedless buds, and let the seeds continue till ripe, if need be.
Has worked great for me for many years, but hey...it's your call of course.