Alder wood chips
Could the new Alder wood chips cause my plants to have brown edging on the leaves - lilies and peonies in particular? Is there too much nitrogen in the chips? Have been watering too but apparently that is not necessary. Not sure what info you are looking for. The plants are in the front and get lots of sun there. Hydrangeas seem to be OK. Thought it might be the wood chips, as I have had other chips out there and not had this problem before. Hope this helps. Sue
I doubt the new wood chips are the cause.
You seem to be questioning watering.
Though mulch will help retain moisture to your garden and plants, you will need to make sure they are receiving adequate water.
Pull back the mulch and check the soil moisture.
If it is dry, your plants will need watering.
Over watering could also be an issue. Is the soil soggy and water logged? If the plants roots are standing in water, this would also cause the plants to show signs of stress such as browning of leaves.
Here are links about the two plants you mention and what care they need.