[header] How to tell the difference between different types of plant fertilizers [title] Use soluble fertilizer when you want to water in the fertilizer. [step] This fertilizer is usually added to the watering can. [substeps] This is best for helping boost growth when its growing season and for frequently fed container plants. 
[title] Use granular fertilizer when you need to supply a concentrated amount of nutrients. [step] A plant may be lacking in a particular nutrient (this will be evident through such things as yellow leaves, , etc.