What causes dahlia leaves to turn yellow?

Dahlia is a favorite food of many flower lovers. If dahlia is properly cared for and has adequate nutrition, it can bloom flowers larger than a bowl and can bloom three times a year. Dahlias bloom in all seasons except the cold winter and early spring. Let’s learn together why the leaves of dahlias turn yellow.

1. The impact of high temperature on flowering

Dahlias usually bloom their most beautiful flowers in early summer and early fall because the temperatures in these two seasons are suitable for the plant to grow and bloom. However, in the high temperatures of midsummer, dahlias may experience misshapen flowers and yellowing and wilting of leaves. To help survive the hot July and August months, provide adequate shade to avoid direct sunlight from midday to afternoon, while maintaining adequate light at other times. Different varieties have different heat tolerance. If some varieties can adapt to full sunlight, no shading is required.

2. Branch rot problem

In summer, dahlia branches are susceptible to rot, usually at the roots, which can cause the entire plant to wither. Branch rot can be caused by a variety of factors, including standing water, disease, insect infestation, or improper pruning. As a bulbous plant, dahlias require good drainage and air permeability, so measures should be taken to avoid water accumulation during the rainy season, such as placing potted plants in a sheltered area or digging drainage ditches for ground-planted plants. Diseases often occur with stagnant water and can be prevented and treated by using specific agents. Pests can be identified by checking for excrement on branches and controlled using appropriate pesticides. When pruning, avoid letting rainwater get inside the branches to reduce the risk of rot.

3. Prevention and control of thrips

Thrips feed on the tender tissues of dahlias, causing stunted growth and deformed flowers. Thrips control can be achieved by spraying the plants with specific agents.

4. Branch management and bud thinning

If the branches of dahlia are too dense, they will compete with each other for light and nutrients, affecting flowering. Pruning removes dense or weak branches and provides space and nutrients for the growth of healthy branches. In addition, it is also important to thin out the flower buds. Keeping only one flower bud on a branch can concentrate nutrients and make the flowers more colorful. Before pruning, observe and select the strongest buds to keep.

In short, through effective pest and disease control, proper shading and branch management, dahlias can usher in a new round of blooming in September after summer.