Rhododendrons

Question

Should I use compost, a Compost-peat mixture, or commercial fertilizer?

Answer 1

All can be used to feed Rhododendrons. It will depend on what is available to you.
Compost is ideal, especially if you are composting yourself.

Here are some links to help you.

https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/fertilizing-rhododendrons.htm
https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/how-to-fertilize-rhododendrons.htm