why put manure onto rhubarb
1 Be sure to mix compost, rotted manure, or anything high in organic matter in the soil. 2  Rhubarb plants are heavy feeders and need this organic matter. 3  Don't add a chemical fertilizer when planting rhubarb or during the first year of growth.hen it comes to rhubarb, you want to divide the plant every 3 to 6 years to keep it healthy. You'll pry open the crown into 3 or 4 separate pieces that each have an 'eye', or a large bud that will provide next year's shoots. Dig over the soil 4 weeks before planting and adds loads of organic matter.