I have an area in my back yard where I have about 15 rhubarb plants. As this area gets closer to a large cedar tree, the rhubarb has started to die out. Is there some fertilizer or other nutrients that can be added to the soil to get the rhubarb growing again? I have some Goat manure that I have added, but it does not help. Any suggestions. Could you possibly test the soil to see what is needed?
Soil needs for rhubarb include drainage, moisture and organic matter. Root competition from a big cedar could become an issue, as roots reach much further than the foliage drip-line. A big tree might cast shade on your rhubarb as well.
Details about soil ph and recommended amendments when planting are included in this publication. Note that manure, if used, is best aged first.
Grow Your Own Rhubarb, from OSU Extension: https://catalog.extension.oregonstate.edu/ec797/html
Soil tests in our area are available from A&L Western Agricultural Labs. Call about costs, how to prepare samples, and which tests they recommend for rhubarb.