Fertilizing Pepper Plants: Everything You Need to Know

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When it comes to understanding fertilizer, it can sometimes be difficult to grasp all of the complex nutrients, dilutions, and ratios needed to grow healthy pepper plants. We’re gardeners after all, not chemists.

But don’t worry! Let this article be a starting point for understanding the ins and outs of fertilizer. I’ll go over everything you need to know about fertilizing your pepper plants to hopefully make it easier on you. 

I’ll also talk about some good natural fertilizer options as well as explain what you need to do if you accidentally over-fertilize your plants. 

So, let’s get into it! 

Understanding soil nutrients

There are 3 key nutrients that your pepper plants need to survive and thrive: nitrogen, phosphorus, and potassium. Also known as, NPK. These nutrients are what are known as macronutrients meaning plants need mostly these three to grow.

Nitrogen (N) is crucial in the development of foliage and leaf growth. It’s thanks to nitrogen that your plants grow to be big, bushy, and full. 

Phosphorus (P) is what helps the plant take in the sun’s energy and ultimately makes it grow.

Potassium (K) makes it possible for your plants to transport any water or nutrients between the roots, stem, and leaves. 

While nitrogen is best for foliage growth, phosphorus and potassium often work together in fruit development. 

When purchasing fertilizer, you’ll notice that the packaging will have 3 numbers on it. It may say something like 5-10-10, 3-5-4, or 6-4-4. These numbers represent the macronutrients we just went over.

The first number represents N, the second number represents P, and the third number represents K. If a fertilizer has an NPK ratio of 5-10-10 it means that it is made up of 5% nitrogen, 10% phosphorus, and 10% potassium. 

Soil testing

Before applying ANY kind of fertilizer, do a soil test. Knowing what nutrients are in your soil (or aren’t) will play a crucial part in dictating what fertilizers and amendments need to be added if any.

To get an accurate picture of the makeup of your soil, try to get your soil tested through your local agriculture extension agency. 

They’ll be able to tell you what nutrients your soil may be lacking or have excess in as well as offer you advice on the best amendments for your soil.

If you don’t have an extension agency nearby, then you can order basic soil tests online and test your soil at home. Keep in mind that home soil tests may not be as accurate as lab testing, but they should give you a good place to start. 

How to apply fertilizer to peppers

Now that we’ve gone over the boring stuff, let’s get to the peppers. Depending on what stage of growth your peppers are in, the type and amount of fertilizer you use will vary. 

Granular vs. liquid fertilizer

There are two main forms that fertilizer usually comes in, granular and liquid. Granular fertilizers look like small pellets that can be applied as-is on the surface of the soil where your peppers are planted. 

The important thing to note about granular fertilizers is that they’re usually slow-release. This means that they slowly break down in the soil over time and don’t provide all of their fertilization at once. 

Because of this, they don’t need to be applied as often as many liquid fertilizers do. 

Liquid fertilizers are exactly what they sound like. Fertilizer in liquid form. Liquid fertilizers cannot be applied directly to your pepper plants because they are heavily concentrated and therefore must be diluted. 

Dilution is the process of adding water to your fertilizer to make it significantly less concentrated. To dilute a liquid fertilizer, first, check the packaging for the correct measurements and ratios. 

Ratios will vary depending on the fertilizer you’re using but in general, you only need about 1 tablespoon of fertilizer per gallon of water. 

Fertilizing young pepper seedlings

When your pepper seedlings first emerge from the ground, don’t fertilize them right away. Wait until they are at least 2 weeks old before adding any amendments. Seedlings that are too young are much more susceptible to fertilizer burns.

For seedlings in plug trays, I like to use Neptune’s Harvest. This fertilizer is a fish emulsion fertilizer and is made of fish that have been ground up and processed into a liquid. 

It sounds kind of gross and, believe me, it doesn’t smell or look all that great, but the plants love it so I can’t complain too much. 

To apply the fish emulsion, I dilute the fertilizer in a 5-gallon bucket. For Neptune’s Harvest, the dilution ratio is 1 tablespoon of fertilizer to every 1-gallon water. 

I don’t usually fill the bucket all the way with water as it can get quite heavy. I will fill the bucket halfway so that it has about 2 or 3 gallons in it. Then, I add the fertilizer and give it a good mix.

Once I’ve mixed it well, I will then pour the fertilizer mixture into some kind of plastic bin. To fertilize the pepper seedlings, I take my plug trays and gently place them on top of the fertilizer mixture. I count to 10 and then remove the plug tray from the mixture.

I repeat this process for however many trays of seedlings I have. 

With this method, the seedlings are absorbing the fertilizer through the holes in the bottom of the plug tray and it’s going straight into their roots. 

It’s also important to note that I only do this when I’m getting ready to transplant my seedlings outside. Not only have they been given a boost of fertilizer, but their root balls are also good and hydrated now which helps to prevent transplant shock.

Fertilizing mid-sized pepper plants

Now that you’ve transplanted your peppers outside or they’ve at least grown to be almost a foot tall, it’s time to switch up the fertilizer. 

Neptune’s Harvest is still a great option and can be used on any sized pepper plant, but for maximum fruit production, it’s best to switch to something with a higher potassium and phosphorus ratio.

As your pepper plants start to get bigger and develop more leaves, you’ll want to move away from fertilizers that are higher in nitrogen.

At this stage, using fertilizers that have a higher nitrogen ratio can encourage bushy leaf growth in your peppers but may limit their fruit production. What good is having a bushy pepper plant if it won’t even grow peppers?

I would switch to a fertilizer that has an NPK ratio of 5-10-10. Some good options include the Morcrop Tomato & Vegetable Food or the Fox Farm Organic Liquid Plant Food. 

The Morcrop fertilizer is a granular fertilizer meaning its application will be a bit different than the Fox Farm liquid fertilizer which will have to be diluted with water. 

To apply a granular fertilizer, you simply need to sprinkle it on the soil around the base of the plant. Take special care not to let the fertilizer touch the plant as it can cause serious burns to it.

Again, check the packaging of the fertilizer to know exactly how much to apply. When I use granular fertilizers, a small handful of the granules sprinkled around the base of the plant seems to do the trick. 

Don’t forget to water the granular fertilizer in. Or, if you know a good rain is coming, then let mother nature do the work for you. 

Fertilizing mature pepper plants

Once my pepper plants start producing consistent fruit, I usually roll back on the fertilizing if not stop altogether. 

Although, continuing to fertilize your mature pepper plants can help to prolong their life and keep them producing well into the fall. 

If the fertilizers you have been using up until this point have been working well, then no need to switch them. Continue to use what you have been using but roll back on the amounts and/or frequency of the application. 

If you think you might need to try a different fertilizer then look for a granular, slow-release fertilizer that you can sprinkle on the surface of the soil where your peppers are buried. 

Slow-release fertilizers are great because you don’t have to apply them as often and they don’t usually release very high concentrations of nutrients. 

Again, be careful not to let any of the granules touch any of the leaves of the plant as they can cause serious burns to the foliage. 

How often to fertilize peppers

When seedlings are young most people like to apply a liquid fertilizer about once a week. As I described earlier, it’s best to bottom fertilize the seedlings so they can absorb the fertilizer directly into their roots. 

Alternatively, you can also apply the fertilizer as a foliar spray. 

I only apply fertilizer to my seedlings once and that’s right before I transplant them outside. If you plan to fertilize your seedlings every week, then you only need to use about half of the recommended dose of fertilizer. 

Once your pepper plants have grown a bit, you can scale back to fertilizing them about every other week. As my peppers reach maturity, I even scale back to fertilizing only once a month. 

Just remember to keep track of whatever schedule you choose so that you don’t accidentally over or under fertilize your peppers.

Best natural fertilizers for pepper plants

A lot of the time, I like to opt for natural fertilizers instead of the high-chemical ones often available at most lawn and garden stores. 

Some great natural fertilizer options include compost, bone meal, blood meal, worm castings, and even animal manures.

It’s important to note that these fertilizers tend to have much smaller ratios of NPK than you might find in other commercial fertilizers out there. 

This isn’t a bad thing, just something to keep in mind if you’re looking to add a hefty dose of nitrogen, phosphorus, or potassium to your soil.

Should you still fertilize after adding other amendments?

If you’ve added any amendments such as compost, straw, sawdust, etc. to your soil, then adding fertilizer may not be necessary. 

Sometimes all your soil needs is a good layer of compost to add the necessary nutrients needed for healthy plant growth back into the soil. 

The best thing to do would be to wait and see how your peppers do after planting them into already amended soil. If they look like they need a bit of a boost, then go ahead and fertilize them.

If they seem to be doing fine without fertilizer, then hold off on applying any. You don’t want to run the risk of adding excessive amounts of nutrients to your fertilizer as this can negatively affect the growth of your peppers.

What to do if you over-fertilize your peppers

While fertilizers can be extremely beneficial to the growth of peppers, it is possible to overdo it. If you apply too much fertilizer to your peppers, then you’ve given them way more nutrients than they can take in. 

When your peppers have been overfertilized, you may start to notice that their leaves turn yellow and curl at the edges. If left untreated, this can be fatal. 

The best thing you can do for your peppers is to stop fertilizing them immediately and flush them. Giving them a heavy water will help to flush out any excess nutrients that they may be holding in from the fertilizer. 

While you want to water them a little heavier than normal to flush them out, be careful not to overwater and drown them. 

Make sure your peppers have good drainage so that they don’t end up sitting in a pool of water and rotting.

In summary

So there you have it, now you have all the information you need to properly fertilize your pepper plants and grow big beautiful peppers this season. 

It can be a lot of information to take in at once, so let’s do a quick recap of the highlights:

• The 3 major nutrients that your pepper plants need are Nitrogen, Phosphorus, and Potassium.
• Fertilize young seedlings with well-rounded liquid fertilizer about once a week.
• As your peppers mature, switch to a slow-release granular fertilizer with higher ratios of phosphorus and potassium to promote fruit production. 
• Scale back on the frequency of fertilizing mature pepper plants. You only need to fertilize them about once a month. 
• Be careful not to over-fertilize your peppers as this can ultimately kill them. Try to flush them out to help prevent any serious damage from the excess fertilizer.