When it comes time to harvest your crop (with a right click) your plant will drop a varying number of item, each time you harvest the quality of your produce is random, the crops will be a mixture of three tiers which increase in rarity: Common, Uncommon and Rare
There are currently 4 types of fertilizer.
Retaining: this fertilizer contains gravel, flint and clay and gives your pot a chance to retain moisture overnight due to the large stone sizes, the only obtainable tier is the first
Speed: this fertilizer contains bonemeal and rooted dirt and increases the nutrition in the plant’s soil giving it a chance to grow two stages overnight rather than the normal one, the first tier can be obtained through crafting and the second as a rare drop from fishing chests.
Quality: this fertilizer contains rare compounds and natural hormones to allow the crop to grow to larger sizes and increases the chances to produce a higher tier, only the first tier is available and the second can be caught as a rare drop from fishing chests.
Yield: this fertilizer contains powerful nutrients which promote the growth of a larger yield causing the crop to drop more produce the first tier can be caught as an uncommon drop from fishing chests.
The first tiers of speed, quality, retaining, and yield respectively.
A pot displays green particles when it has been right clicked with fertilizer.