Answer: Peppers generally do best in a soil with average fertility and plenty of organic matter worked in. The soil should be kept evenly moist but not soggy and a mulch applied after the soil has warmed is helpful. If your soil is rich, an excessive application of nitrogen could result in excess foliage growth at the expense of peppers. Planting too early while the soil is still cold or otherwise stunting the plants can also reduce yield.
Over the season, production and plant health can vary on so many factors, ranging for example from the condition of the plants you set out to the actual variety you planted to the nighttime temperatures and amount of rainfall and so on. However, I would doubt that the timing of the fertilizer would have had such a drastic effect!
A balanced fertilizer (or one with a higher middle number), either granular or water soluble, applied according to the package instructions should do just fine. As an example, many gardeners will work some fertilizer into the soil during the preparation process prior to planting, apply a transplant solution or compost tea at planting, and then side dress periodically during the growing season.
Good luck with your peppers!
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