Starting Pepper Plants Indoors – A Full Guide To Starting Seeds

Living in a climate with a winter season can be enjoyable. You can get out and do some skiing, watch the calming snowfall, maybe pack a snowball and throw it at your friends.

However, winter is also downtime for gardeners. Cold weather shortens the growing season for outdoor growers. This means that starting pepper plants indoors is necessary.

Pepper Geek participates in various affiliate programs, meaning links contained in this article may provide us a commission should you make a purchase on the linked website.

Starting Pepper Plants Indoors

This article will cover the basics on how to start pepper plants inside at the beginning of the growing season. Maybe you saved some seeds from last year, or you’re growing for the first time.

We will focus on peppers, but these planting guidelines can also apply to many other slower-growing nightshade plants, like tomatoes and eggplants. Let’s get started!

Skip Ahead:


When To Start Pepper Seeds Indoors

Exactly when to start your peppers will vary based on your region. In general, pepper plants need about 8 weeks indoors before transitioning to a permanent outdoor spot.

Simply put, start pepper seeds indoors 6-8 weeks before your last date of frost. In warmer regions, the growing season will be longer, and plants can be started earlier to extend the grow season.

When to plant pepper seeds indoors (chart).

One of the best ways to increase your pepper plant’s yield is to start from seed indoors in late winter. This allows the pepper plants to fully mature by the end of the season, producing the maximum number of ripened peppers.

In Northern climates, plants are typically started later (we New Englanders start pepper seeds in early or mid-March). With the proper grow light setup, you can start your plants very early to truly maximize the growing season.

Note: If you are growing superhot varieties, start them 2 weeks earlier than other pepper varieties – they take a long time to germinate and mature!

For an exact recommended start date, enter your postal code here.


How To Start Pepper Plants Indoors

When starting seeds, they require little or no nutrition to germinate. This is because the seeds themselves contain the necessary nutrients to get started. All that a pepper seed needs to begin germination is water, oxygen and warmth.

See our top tips for germinating pepper seeds fast here.

For peppers, the best seed starting soil is something organic with good aeration. This mix on Amazon will work well, as it contains peat moss and perlite to promote healthy root structure.

Tip: It is important to use fresh seed starting mix when starting plants indoors to avoid insects and mold. Using leftover seed starter from indoors can invite these pests into your home, so beware!

Starting your seeds generally consists of the following steps. Keep in mind that the germination process is usually pretty quick for peppers, and transplanting to larger pots with nutrient-rich soil is next.

How to Start Pepper Seeds Indoors:

  1. Use a starter soil.

    Starter soils have no nutrients and good aeration. We recommend something organic like this one on Amazon.

  2. Get seed starter trays.

    We love these built-to-last trays from Bootstrap Farmer. The trays should have a humidity dome to keep the seed mix moist during germination.

  3. Pre-moisten the soil.

    This helps with root formation and better water absorption in the future. Thoroughly mix with water until the soil is damp and sticks together when squeezed, but doesn’t drip.

  4. Fill containers with soil, compressing lightly.

    Compress until you feel resistance, and then add more soil until each cell is filled to the top.

  5. Push a small hole 1/8-1/4 inch into the soil.

    Alternatively, place the seeds on the surface and push them below the soil with a pen or pencil tip. Any deeper than 1/4 inch, and pepper seedlings may have trouble properly surfacing above the soil.

  6. Drop 2+ seeds into each hole.

    If you have limited seed quantities, just use one seed per cell. Using 2 or more seeds helps increase the odds that at least one will sprout. If you end up having multiple seeds sprout, you can simply pluck one of them.

  7. Cover with soil.

  8. Water lightly.

    Use a spray bottle to lightly mist and moisten the soil around the seed. This ensures enough moisture is on the seed to initiate germination.

  9. Keep warm with a seedling heat mat.

    We use this affordable heating mat from Amazon to keep our seedlings at a consistent 80°F. It comes with a probe that stays in the soil, measuring the temperature and automatically turning on and off the heating mat to reach the desired temperature. Highly recommended for the best germination rates!

  10. Keep in a dim and warm area.

    Pepper seeds typically take around 7-10 days to sprout, and before sprouting they do not require light. The ideal temperature is between 80-90°F. This will ensure that the seeds germinate as quickly as possible.
    Mist as necessary, or provide water to the bottom of the trays to keep the soil moist (but never soaking wet). Once the seeds sprout, immediately move them under grow lights and remove the humidity dome.

After your seeds have sprouted, you will need to provide ample lighting. Without enough light, your plants will grow to be leggy and weak. This may translate to a tall, lanky pepper plant that may under-produce.

To give your seed starts the light they need, we highly recommend using a grow light.


Which Grow Light Is Best For Starting Seeds?

Seed germination does not require light. However, once the seeds have sprouted, a grow light should be used. This will allow the leaves to photosynthesize and produce their first sets of leaves efficiently.

See our recommended grow lights for peppers here.

Can I Use A Sunny Window?

It is common for gardeners to simply place seedlings in a sunny windowsill for light. While this may seem like enough, it is not ideal for peppers. When choosing a window for your seedlings, consider these factors:

  • Is the window south-facing? (South gets the most sunlight)
  • Are there any obstructions to the sunlight outside? Trees? Fencing?
  • How many hours of direct sunlight does the window actually receive?
  • How far north are you? The farther north, the less winter sunlight you are receiving each day.

The reality is that most windowsills are not ideal for young seedling growth. Your seedlings need LOTS of strong light for at least 12 hours per day, but ideally for 16-18 hours.

While a windowsill will certainly help the plants grow, you will likely find that they become leggy (tall and lanky). It is also usually colder near windows, leading to slower growth. This can cause weaker plants and lower yields in the long run.

What Kind Of Light To Use?

There are an overwhelming number of grow light options available. For the purposes of this article, we will recommend two grow lights. One for a casual grower with a few small pepper plants, and one for a larger project, with 10-20+ plants.

If you expand your garden, you can always use additional grow lights and be creative with your setup.

  • Clip-On Grow Light
    This light is affordable and does not require any hanging to position the lights. You can simply clip the light onto a table, plug it in, and bend the lights to the desired height. This particular light on Amazon also has a built-in timer to have the light turn on and off at different intervals. This light is not very strong, so keep the lights close to the seedlings.

    *Don’t expect these cheap clip lights to last very long, we have already had one of ours stop working after about a year. The convenience is attractive, but investing a bit more money goes a long way.
  • LED Panel Light
    A hanging grow light typically requires more setup and space but also has more power to grow larger plants. A hanging LED light also allows the plants to grow taller by moving the light up as the plants make progress.

    A clip-on light may have a limit to how high the plants can grow. Hanging lights can also be bought with more wattage and power. Be careful though! Too much light can cause damage to tender, young plants.

For another quality light option, check out this unit from Spider Farmer.

This is by no means a comprehensive list of grow lights. However, one of these will almost certainly be adequate for starting your pepper seeds indoors. If you are looking to do full-grown plants, you may want to consider a larger lighting setup, and perhaps even a grow tent.

How Close Should A Grow Light Be To Seedlings?

This is a critical element of starting plants indoors. Once your seedlings sprout, you want your lights to be as close as possible to the plants without causing damage.

For typical LED grow lights with low power (~20W), the lights should be positioned 2-3 inches above your seedlings. Stronger lights (80-150W) should be much higher, between 12-24″. Lights can be closer as the plants grow larger and become more hardy.

Keep the lights on for 2-3 weeks on a 16-hour-on, 8-hour-off schedule. If the plants appear to have burning or rolling, the lights may be too close to the foliage. Move the lights higher to avoid further plant damage.

As the plants grow larger and begin to fill out their foliage, they will outgrow the small seed starting trays. This is when we recommend transplanting the pepper plants into larger pots indoors.

Tip: Be sure you have enough lighting and space for the number of pepper plants that you have planted. If you use inadequate lighting, your plants may not reach maximum potential.


Transplanting & Fertilizing

If you started seeds in small seed trays, they will soon need a larger container. Once your seedlings reach 2-3 inches in height, it is time to transplant to a larger pot. With proper lighting, the plants will develop a strong root system. This will help make transplanting easy.

Steps to transplanting your started plants:

  • Get 3-inch nursery pots. These are perfect (or these for a higher quality option).
  • Get some standard potting mix. Get something with a full range of nutrients. Choose an organic option if possible.
  • Pre-moisten the potting soil. Wet the mix with water and mix thoroughly until evenly moistened, but not soaked. We use a large bowl or a wheelbarrow for larger gardens.
  • Fill each pot with soil. Fill the pots with soil, compressing until you feel some resistance. Don’t over-compress, but don’t be too gentle either!
  • Dig out a hole. Make sure it’s large enough to fit your seedling’s root system.
  • Place each plant in its new pot. Be careful not to damage the root system while handling the plant. Try to pull the plant out gently by the base of its stem. Loosening the soil slightly can help. Also, I like to make sure the started plants are lightly watered before transplanting.
  • Cover with soil and compress. Be sure to avoid burying any of the plant stem that was not below the surface. Keep the plant at the same level above the soil where it was previously. Young pepper stems can rot if buried with moist soil.
  • Water immediately. Water thoroughly to ensure the root system is moist and integrates well.

This is almost an identical process to starting the seeds, but instead of putting seeds into the soil, you’re moving the whole plants. Giving your starts adequate soil and space allows the plants to continue to grow without getting stunted. Without enough room, the plants will stop growing.

Fertilizing

Once you have transplanted your peppers, it is time to start your fertilizer regimen. Potting mix often contain some fertilizer, but it is best to supplement with the ideal nutrients regularly.

At this stage, we like to start lightly fertilizing every 2 weeks with a nitrogen-rich fertilizer. Any fertilizer with an even 5-5-5 or 10-10-10 makeup will work well. Use at 1/2 the recommended strength. Don’t water too heavily when fertilizing, and be sure not to over-soak the soil.

We use this fertilizer for early growth.

We switch to this fish-based fertilizer once the plants have been outdoors for 2-3 weeks in an established location and begin producing flowers.

Tip: Make sure you have good drainage for your pots. If the water is forced to stay in the soil, it can cause rotting and insufficient oxygen levels.

As the plants grow larger, and your lights are moved higher, the light will become more scattered and less effective. The plants will either need stronger artificial lighting or, ideally, be moved outdoors into the sunlight.


Hardening Off Pepper Plants

After the risk of frost has passed in your area, you can begin hardening off your pepper plants. “Hardening off” is the process of transitioning your plants from indoors to outdoors.

Read more about hardening off pepper plants properly here.

It may be tempting to simply put your plants directly into the ground, but this will likely cause shock to the plants. Shocking your plants can cause stunted growth, sun scald, and dying leaves.

The proper method is to gradually keep the plants outside for longer and longer each day. Doing so allows your pepper plants to get used to the elements, like direct sunlight, wind, and varying temperatures.

Here is our method for hardening off plants:

  • 1st week: 20 minutes sunlight, or 1 hour of shade
  • 2nd week: 1 hour sunlight, or 3-4 hours of shade
  • 3rd week: 1.5-2 hours sunlight, or all day in shade
  • 4th week: Transplant outdoors permanently
Hardening Off Pepper Plants
Hardening off our pepper plants

This can be time-consuming and tedious, but if you keep your plants on a tray or a wagon, it can make the moving process easy. You can also do this more aggressively, as our method is very conservative and safe.

For a full pepper growing guide, read our article on growing habanero peppers here!

Once your plants are used to the outdoors, you can transplant into the ground or large nursery pots for the season. Make sure they get the nutrients and sunlight they need. Enjoy and good luck!

Calvin Thumbnail

Calvin

One of the original Pepper Geeks! When Calvin isn’t gardening or learning more about peppers and botany, he might be traveling new places or playing some music.

11 thoughts on “Starting Pepper Plants Indoors – A Full Guide To Starting Seeds”

  1. Hi Calvin,

    I’ve successfully germinated pepper seedlings but they now appear to be having difficulty growing a third set of leaves. The seedlings are in peat pots with seedling starting mix; I feed with dilute liquid fertilizer every other watering and am careful not to overwater. The seedlings are under grow lights much of the day and the indoor temperature is about 75 degrees. What can I do to further encourage growth? Would a heat mat be at all helpful at this stage? Sun exposure outdoors? Transplanting them into more nutritious potting soil?
    Thanks!

    Reply
    • Hi there,

      Well it sounds like the environment is good (temp, light, etc.), so you may just need to transplant to larger containers – how big are the peat pots? Getting them outside should also be prioritized as soon as the weather permits, just be sure to harden off the plants gradually. If they’re just in peat moss, then yes, I’d recommend moving to a more well-rounded soil mix or into the ground. Good luck with your plants!

      Reply
      • Hi Calvin,

        They are in 3” round Jiffy pots and seedling starter mix. I can certainly transplant them into better soil and begin hardening them off if you think that will help. They just seemed so small and fragile, I didn’t want to move them unless it seemed like doing so would be helpful.

        Thanks!

        Reply
  2. I have a tsw2000 led light, my question is how far above the peppers should light be? We are at 1-2 sets of true leaves and have the light turned right up and about 8” above them. Day time temps are roughly 75 f, night time 66-67 f. Humidity runs around 40-45. First time grower any suggestions are greatly appreciated, thanks.

    Reply
    • I would definitely raise the light up to around 20″ or so if it is on full-blast. If you can dim it, I’d do that too, maybe to around 50%. That is a 300W light, so very powerful.

      Reply
  3. Hi Calvin,
    First time pepper seed growing and my plants are a little leggy because I didn’t realize they had started to sprout before adding the light. I have since added light and they are standing now and look much better, but is it too late?

    Reply
    • No! We accidentally had one of our lights on for 24 hours a day last year and we had some pretty bad leaf curl. The timer was accidentally set to “ON” instead of “TIMER.” I recommend 14-16 hours a day for new seedlings on a low intensity or higher hanging height.

      Good luck!
      -Calvin

      Reply
  4. Hi Calvin, what sort of room temperature should I be aiming for at the 4th true leaf pair stage, is it still around 80 deg F or can it be cooler?

    Many thanks!

    Reply

Leave a Comment