Q.delphinium leaves dying and turning brown
Why are some of my delphinium leaves dying and turning brown? Their stems are brown all the way to the ground. This happened after a spectacular round of blooms.
This could be caused by watering issues, to much or to little.
If the plants are to dry they may be dying down prematurely. If the ground is wet and excessive damp conditions it can cause root rot.
I would trim away the dead material and treat the plants with Neem Oil. This acts as both an insecticide and fungicide. Stressed plants can invite both.
Here are a few article for you.
https://www.gardeningknowhow.com/ornamental/flowers/delphinium/delphinium-winter-care.htm
https://www.gardeningknowhow.com/ornamental/flowers/delphinium/growing-delphinium-plants.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm