Dahlias and sunflowers both require ample sunlight, but sunflowers can grow taller and potentially shade dahlias, leading to insufficient light for the latter’s growth.
Sunflowers can reach towering heights, which might overshadow shorter dahlias. This height discrepancy can affect the dahlias' ability to receive adequate light and space.
Dahlias and sunflowers have different water requirements. Sunflowers may need more frequent watering, which can create overly wet conditions for dahlias, potentially causing root rot.
Both plants have strong root systems that can compete for soil nutrients. This competition can deplete essential nutrients needed for optimal growth of dahlias and sunflowers.
Sunflowers can attract pests that might also target dahlias. The presence of pests on sunflowers can lead to increased risk of infestations affecting nearby dahlias.
Sunflowers and dahlias might have different soil preferences in terms of pH and texture. Planting them together might not meet the specific soil needs of each plant, impacting their growth.
Sunflowers have extensive root systems that can encroach on the space needed by dahlia roots. This overlap can inhibit the growth and health of dahlias by restricting their root expansion.
Tall sunflowers can block air circulation around dahlias, increasing the risk of fungal diseases and reducing overall plant health for dahlias.