1 litre sized pot.  Rudbeckia laciniata Golden Glow is a herbaceous perennial that produces tall stems (1.2m+) bearing bright yellow large double flowers.  It thrives in the sun in moist but well drained soil and will create a larger spreading clump (without being invasive) if it is happy in its surroundings.  Flowers will continue from summer till first frosts.  Great as a cut flower.  It has dark green leaves and the stems can be cut back to ground level once it has finished flowering or in winter/early spring.  I have some Golden Glow intermingling with Chrysanthemum Red Flame and Aster Calliope to create a bold bright display.