Are these flowers too close together?

I'm planning to start a garden in my yard soon. However, I have a limited amount of space (3 ft by 3 ft) and I'm going to plant three different flowers: Marigold (Scarlet Starlet), Marigold (Dward Bolero), and Black-eyed Susan (Rudbeckia Hirta). Is there enough room to grow all of these plants and let them grow healthily?