You have a lot of options when it comes to how and when you fertilize (feed) your chili peppers.
As you become an experienced grower, you'll develop your own preferences based on your climate, soil conditions and pepper growing environment (for example, in a pot or in the ground).
If you're new to chillies and even if you've already grown a few plants, this can all be very confusing. Below is an example feeding schedule for those who start pepper seedlings in containers.
Test this out and make adjustments (if needed) throughout your growing season.
Why We Fertilize Peppers
Your pepper seeds have just enough energy to support the cotyledons, which are the embryonic leaves that first appear. After that, pepper plants need help to build a strong structure and eventually grow fruit.
When fed well, peppers display green leaves (unless they are a variety like Black Pearl), thick stems, lots of flowers and vibrant pods.
How to Start Fertilizing Peppers
After the first set of true leaves appear, you can start using a diluted amount of fish emulsion or fish and seaweed fertilizer to help along seedling growth.
Read the instructions on the container and then use 1/4 strength when you water your plants.
After your plants have three or four sets of true leaves, you can apply magnesium sulfate (epsom salt) directly to the leaves and stem.
Epsom salt keeps the plant foliage strong, and prevents light green to yellow leaves from developing.
Make sure that the epsom salt you use does not have any additions such as scents or bath crystals.
Add a 1 teaspoon epsom salt to a gallon of water and shake it up well. Pour the mixture into a spray bottle and then spritz the leaves and stems with the solution until thoroughly covered.
Spray your plants every other week so that one week you water with fish emulsion, and the other week you give your plants the foliar feeding.
Feeding Outdoor Peppers
Continue with the fish emulsion / fish and seaweed fertilizer schedule, but this time increase the dosage to about half the amount described on the label.
If your peppers are in the ground, you can use the full amount. Keep the foliar feeding with epsom salts the same.
Your outside chillies will also benefit from some additional nutrients to help them flower, fruit and maintain their health.
Add Compost to Pepper Plants
Not only does compost condition the soil, but it fertilizes your chillies and acts as a natural pesticide to insects.
After your peppers are planted in containers, use a good-quality, organic compost and layer it on the top of the soil.
You also have the option to mix the compost in with your potting mixture.
If you're planting chillies in the ground, drop a handful of compost in each planting hole before you place the pepper plant in it.
Calcium and Phosphorous Requirements
As an added bonus, many growers use a calcium and phosphorous source such as Cal-Mag or bonemeal.
These nutrients help build a stronger plant structure, keeps your chillies flowering and fruiting and prevent blossom-end rot (BER).
If your chile plant ever displays crinkled or bubbly leaves (particularly Capsicum chinense varieties), or if the ends of pepper pods have dark, sunken lesions, you know your plant needs calcium and phosphorous.
Apply the Cal-Mag or bonemeal package by following the instructions on the label. Typically, you mix a designated amount of powder into the top layer of soil and then water your plant.
A monthly feeding of calcium and phosphorous is usually sufficient for peppers.
Water Your Peppers with Compost Tea
You can give your chili plants a huge advantage by watering them with compost tea. This tea is a concentrated liquid of compost that has beneficial microbes that benefit both the plant and soil.
Follow the instructions on your compost tea container to "brew" up a batch of liquid.
Pour the tea in a sprayer and drench the stems as well as both the tops and undersides of leaves so that the excess drips onto the soil.
Do this once or twice a month to fight off foliar disease and promote growth.
Make sure to use the tea within four hours (or whatever time frame is specified on the label) so that it's most effective.
What to Watch For
It's very easy to give your chillies too much fertilizer. This is very harmful to your plant and it can even cause its death.
Never give them more than what is instructed on the label.
After a feeding, especially if you are doing it for the first time, inspect the leaves for browning edges. This occurrence is known as "fertilizer burn," and it lets you know you should cut down on the feeding.
If your pots are outdoors in containers and you detect fertilizer burn, run water over the soil to help flush the excess nutrients out.
(Bonus: Want an easier way to remeber all this information? Subscribe to get a sample feeding calendar to help you get started. You'll also get cheat sheets, which provide all the fertilization steps in a printable, at-a-glance format.
By the way, if you're looking for the fertilizer products mentioned in this post, be sure to check out the Resources page.