I recently retired and plan on spending more time in our garden going forward. I note that our butterfly weed often has branches that seem to just rot off. I had a similar problem with a purple sedum a few years ago- it's totally gone now. Anyway, what can I do to eliminate this problem? The plants are in a mostly clay soil and we have a thin layer of mulch on it. There's never any standing water. I'll attach a picture. Thanks.
Check how moist the soil is under the mulch.
Sharpen a pencil and plunge it into the soil near the plant. If the soil is still wet, the pencil will come back dark on the freshly sharpened area.
As the soil dries the wood will be blotchy- wet and dry.
When the soil is pretty dry the wood will be dry, and the pencil may be hard to push into the soil.
Plants need oxygen in the root area as well as water. In a clay soil this can take a while- clay soil holds water really well, and air enters slowly. This can be great for plants that thrive in moist situations, but can kill most succulents (like Sedum) if you are not careful with the water.
If you need to replant this area add a lot of compost or soil conditioner to the soil. This will help to clump the clay particles into something almost like little beads. Much better to get air and water exchange. Use at least 25% organic matter blended with 75% local soil, and more like 1/3:2/3 for sun plants (ie: 1" compost blended with 3-4" native soil) and as much as 50% organic matter for shade plants. If you can add more compost, and work it deeper this is better.
Thank you for the detailed response. I'll do further research.
