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Pepper Plants Not Growing? These Are The Most Likely Causes

Pepper Plants Not Growing? These Are The Most Likely Causes

Whether you are starting from seeds or transplanting an existing pepper plant, there is a risk that it will not grow and thrive to your expectations. Let’s make sure that you understand the possible reasons for this so that you know what you can do to prevent issues.

The most common reason for pepper plants or seeds not growing is that it’s too cold. If your pepper seeds aren’t sprouting, it may also be because the seeds are too old, or the seeds have molded. If transplanted pepper plants aren’t growing, it may be because the roots are too wet or dry, or the soil has a nutrient deficiency.

Luckily, these problems are easy to fix. 

Why Are My Pepper Seeds Not Sprouting?

Peppers are warm-season vegetables (technically, they’re a fruit), and they are most picky in the germination stage.

Pepper seeds have a 55% germination rate, so no matter how perfect your germination station, you should only expect half of the seeds to sprout. This number is based on fresh seeds from the previous year’s plants; older seeds have a lower germination rate, with seeds older than 3 years barely viable.

Of course, proper seed storage is key. If your seeds are kept in a cool, dry place, the germination rates may be slightly higher, or they may hold for an extra year or two. Seeds kept in temperature extremes, or exposed to sunlight or moisture, will have much lower viability.

Ideal Conditions for Pepper Seeds

Pepper seeds require 3 things for successful germination:

  • 80°- 90° soil temperature
  • Moist, not wet, soil
  • Air circulation

Under ideal conditions, pepper seeds should take 7-14 days to germinate. 

The best way to set up pepper seedlings is to plant the seeds ¼” deep and place the seed tray on a heat mat. Leave the tray under a grow light or in a greenhouse; a window will not provide enough light and may cause temperatures to drop too low at night.

Mist the seeds 2-3 times per day, but be careful with plastic domes that retain humidity. The heat mat will cause excess moisture buildup, which may cause the seeds to rot before they can take in water. If you use a dome, take it off for a few hours per day to promote air circulation.

When Pepper Seeds Don’t Sprout

An easy way to make sure peppers have good growing conditions is to grow them with tomatoes. These two plants should be planted around the same time in the spring, and you can use the tomatoes to diagnose problems with the peppers.

Heat

Tomatoes and peppers require the same germination conditions. Tomatoes will always sprout first, and then peppers will sprout about a week later. If the tomatoes sprout but the peppers don’t, the soil is probably too cold.

Since pepper seeds spend more time in the soil before the seedling leaves emerge, this makes them more susceptible to fungus; especially if the soil is too cold. 

A heating mat is necessary for pepper seeds started indoors. Although tomatoes may germinate in a warmer part of the house, like on top of the refrigerator, it simply isn’t warm enough for peppers. The exception may be if you are using a heated greenhouse, but you should still use a heating mat if the temperature dips below 75° at night.

Water

Pepper seeds should be moist, not wet. 

If the seeds germinate and are yellow or brown, the soil is too wet. The seedlings will probably die within the week from root rot.

If the seeds never germinate, the soil may be wet on top but dry underneath. This can happen with bottom heat and is difficult to diagnose. You can start over by using seed starting mix.  

The goal is to keep the soil consistently moist, and the easiest way to do this is to wet the soil mixture before you plant the seeds. 

Dump the seed starting mix into a big bowl or container, and add water. Mix the water into the soil until it is damp, but water does not drip out when you squeeze it. 

Fill the seed tray with soil, but be careful not to pack the soil. This may contribute to root rot in the future.

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Plant the seeds ¼” deep, and spray the seed tray to wet the soil. This should help keep the entire soil layer moist as long as you spray the soil consistently throughout the day.

Try to spray early in the morning before the soil has a chance to dry out, and continue throughout the day until mid-afternoon. Don’t spray at night, or else the soil may stay too wet and cause rot.

Air

Air circulation is difficult to manage with pepper seeds.

You have to maintain humidity and heat without encouraging mold or rot, which is where air circulation comes in. However, too much air circulation can reduce humidity and/or temperature, so it’s a balance.

Humidity domes can help pepper seeds germinate, but you must remove them for a few hours per day to let the air circulate and prevent mold. 

The best time to do this is at dusk, when the water won’t evaporate too quickly from the soil. This will make sure air circulates before the temperatures drop and the seeds lose light for the night, which can help prevent the soil from becoming too moist and encouraging mold.

Why Are My Pepper Transplants Not Growing?

If you have grown (or purchased) pepper plants for transplant, congratulations! The hard part is behind you. At this stage, peppers are pretty resilient, although they are still picky about the weather.

There are three reasons pepper transplants may not be growing:

  • It is too cold
  • The soil is too wet/dry
  • Nutrient deficiency

Cold

This is the most likely reason your plants aren’t growing.

Peppers need a minimum nighttime temperature of 55°, and a minimum daytime temperature of 65° (source). Plants will wait to produce new, tender growth until temperatures are consistently above these thresholds.

If temperatures are too low during the day, the plants may halt active growth until it gets warmer. If temperatures are too low at night, the plants may begin to show cold damage.

While they can survive a few days to a week of colder temperatures with minimal damage, pepper plants are not likely to survive a light frost without protection.

You can mitigate cold temperatures with a cloche or row cover to conserve heat. 

Traditionally, a cloche is a glass globe, much like the one holding the rose in Beauty and the Beast. It acts as a miniature greenhouse for plants that are susceptible to cold damage.

You can make your own cloche with milk jugs, juice bottles, or any other clear container that is tall enough to cover your pepper plant. 

This YouTuber shows several creative DIY examples (super-short 1 minute video).

If you have a long row or bed of peppers, you can alleviate cold temperatures with a row cover.

Use clear plastic sheeting or frost fabric to create a miniature greenhouse environment around your peppers. Build a frame out of wood, PVC, or other handy building materials, and drape the fabric or plastic over the plants. 

Row covers work best if the fabric is suspended above the plants so as to not touch the leaves. Try to make sure the plastic touches the ground on all sides to conserve the most heat.

Water

Peppers are tropical, warm-season plants. They thrive in heat, but they can be water hogs.

If plants are too dry, they will halt growth until they begin to get consistent water. 

If plants are too wet, they may start to wilt and become mushy.

Unfortunately, overwatering and underwatering can look similar. Both will eventually result in wilting and halted growth. However, underwatering is easier to remedy.

The easiest way to tell if a plant is underwatered is to water it. If it perks up, it was too dry. If it doesn’t, it’s too wet.

If the plant was too dry, start to water more frequently. Peppers are fruits, and they need more water when they are blooming and fruiting. Water early in the morning, and thoroughly soak the root zone to promote a deep root system.

If the plant was too wet, let it dry out. It will look sickly for a while, but resist the urge to water. Wait until the top 1” of soil is dry, and then water thoroughly the following morning. Continue to wait to water until the top 1” of soil is dry until the plant has recovered, then you can begin to water more frequently if needed. See What Are The Signs Of Overwatering Plants? for more information.

Soil

There are a myriad of nutrient deficiencies that can halt growth. Peppers aren’t too susceptible to nutrient deficiency, but low nitrogen, phosphorus, and potassium will restrict root and leaf growth.

Symptoms of nutrient deficiency can include:

  • Yellow leaves
  • Purple leaves
  • Brown spots
  • Stunted growth
  • Curled leaves
  • Stunted or deformed fruit

Use compost each spring to maintain nutrient levels in the soil. If you didn’t incorporate compost into the soil, you can try side-dressing your peppers, but it won’t fix a nutrient deficiency that is currently halting growth.

Instead, apply a slow-release fertilizer with a balanced amount of N-P-K, and wait a few weeks to see if the plants improve. 

If the plants do not improve, do a soil test. It’s possible your pH is too high or too low, which is causing secondary nutrient deficiencies. A detailed soil test will give you more information.

Test your soil and get specific recommendations for addressing deficiencies. Click here to learn more (link to SoilKit by AgriTech).

Other Reasons Pepper Plants Aren’t Growing

Sometimes, plants just don’t follow the rules. If most of your plants look healthy, rest assured your growing conditions are probably not to blame. 

Lemons

Sometimes, a plant is just a lemon- meaning, it was doomed to fail.

Some plants are deformed or stunted due to genetics, and there is nothing you can do to fix them.

If all but one or two plants are healthy, the problem is the individual plant, not the growing conditions. It could be a virus, deformity, or any number of underlying issues. 

The best course of action is to pull the affected plant/plants. Especially if you save your own seed. Don’t allow them to pollinate healthy plants and corrupt your future seed supply.

Variety Packs

If you start your own seeds, keep in mind variety packs contain different types of plants (which… is exactly the point).

This means individual species may grow faster than others, which could cause some plants to appear stunted when they are perfectly healthy. 

If the rest of your plants are growing well, be patient. Some varieties can mature weeks or even months later than others. This may also be more pronounced in hot pepper species. I also have some helpful insights and tips if your peppers aren’t producing.

Pepper plants are one of those veggie crops that start slow, and then give you many more peppers than you thought possible. The best way to ensure healthy plants is to provide an optimum growing environment by building a healthy soil profile.

Learn more about how to make and use compost and improve the overall health of your garden.

Happy planting!

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