I have a pot of Sunpatiens that have tons of leaves but no blooms. i used potting soil with fertilizer in it so I don't know if I should fertilize.
Getting More Blooms on Sunpatiens
Certified GKH Gardening Expert
If you potting mix had a slow release fertilizer, that should be enough fertilizer for your plants.
To much nitrogen will actually inhibit flowering.
Make sure the soil is evenly moist.
You can add a small amount of Phosphorous to encourage blooming. Bone Meal will work for this.
The fertilizer that comes in potting soil usually isn't very high in Phosphorus or Potash which is what the plant needs to encourage new flower development. Look for a fertilizer that is safe for potted plants and that is higher in Phosphorous and Potash than Nitrogen. When looking at the label look for a fertilizer that has higher 2nd and 3rd numbers than the first. The first number is your nitrogen and is used predominantly for foliar development.I think Miracle Gro makes a flower fertilizer or look for something like Super Bloom which is a water soluble fertilizer. Feed according to label instructions preferably early in the morning and make sure the plant isn't dry at the time of fertilization to assure you will not burn the plant. I usually water the day before I feed my plants and then water after the application of the fertilizer to water it into the root zone.