You don't, if you mean Thunbergia alata, the climbing plant known as black eyed susan - its only an annual, though its usual to pinch out the tips to keep it bushy. I can't think you mean Rudbeckia hirta, also known as blackeyed susan, because that hasn't started flowering yet. If its some other plant, please add that information below this answer.

I have "Black-Eyed Susan, Indian Summer." Right now it just has big fuzzy leaves. It will start blooming mid July and keep going until frost. Just dead head the spent blooms to keep it fresh & tidy looking.

I think you must be talking about the Rudbeckia as suggested by bamboo and Bathgate.
I leave mine and cut out the last years growth in the spring when the new growth is only a few inches tall.

if you were thinking of the 'Chelsea Chop' to encourage more side shoots that should have been done late may early June . then you remove the top 1/3 to 1/2 of the growth.

Good advice Seaburngirl. I just started mine from seed this year back in February indoors. They are now in the flower bed & growing vigorously, but all I have is huge fuzzy leaves. Should I expect flowers this year? I did the "Chelsea Chop" to my Asters & Chrysanthemums.

In your area, Bathgate, I would expect the newer, dwarfer varieties to bloom in late summer, early fall. The older, taller kinds often don't bloom until the second year. Varieties of Rudbeckia hirta or R. fulgida, anyway.

thanks