Starting Peppers From Seed: The Secrets to Strong Pepper Seedlings

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I’d vote for peppers as one of the easiest crops for brand new gardeners to grow. A member of the Solanaceae (nightshade) family, pepper plants are determined, adaptable, and much less bothered by pests and disease compared to other nightshades like tomatoes. Even if my garden is having a rough year, I can count on harvesting peppers and making lots of hot sauce and hot pepper jam when fall rolls around.

Peppers are also an ideal candidate for container gardening, and they’re known to produce huge harvests even in small containers like 5-gallon buckets. They just don’t care!

Peppers are a popular crop to grow, so you’ll have a decent selection of pepper seedlings to choose from during the spring. As always, though, starting your own from seed gives you a chance to grow less common and interesting varieties you probably wouldn’t find at the nursery or garden store. It’s also cheaper, as good-quality garden seedlings are more expensive than ever in recent years.

While they’re pretty tough plants once mature, pepper seedlings need a tad bit of special treatment to get them off to a strong start. They’re not hard to grow from seed, though, once you get a handle on their quirks.

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When to Start Pepper Seeds

It’s important to start your pepper seeds at the right time to get a big harvest. Even though we mostly grow them as annuals here in the States, peppers are perennial plants in their native warm, tropical regions. They grow slowly and take a pretty long time to set and ripen fruit.

All pepper varieties are also cold-sensitive, and they’ll easily get wiped out by even a light frost. Those of us in cold winter climates need to get them in the ground early enough for them to produce a bumper crop before that first frost in the fall.

Variety matters!

Some types of peppers take longer than others to grow and produce. Varieties in the Capsicum annuum family, such as jalapeno, bell pepper, poblano, and cayenne, mature in around 80 to 90 days after transplanting seedlings. Peppers in the Capsicum chinense or Capsicum baccatum families can take up to 120 days or longer. These are most of the hotter peppers like habanero, scotch bonnet, ghost pepper, and aji. You can find your pepper varieties’ days to maturity on the back of your seed packets.

Most pepper seed packets will tell you to start seeds 8-12 weeks before your last expected frost date. Kinda leaves you guessing, doesn’t it? In my experience, the best timing depends on the variety.

Since hotter pepper varieties take longer to germinate and grow to transplanting size, I try to start those at around 10 weeks. I start C. annuum peppers a little later, at 6 to 8 weeks. I’ve found that starting at 12 weeks is much too early for any variety, and I’ll end up with overgrown seedlings way before the weather is warm enough to plant them out.

Keep in mind that your average last frost date probably won’t be your target planting date for peppers. You’ll need to wait until nighttime temps have warmed up some, which might be several weeks beyond that date.

Once you’ve grown peppers from seed several times, you’ll be able to nail down the ideal time to start them based on your own local weather trends. Recording your seed-starting dates in a garden journal will help you identify any adjustments you need to make in your sowing schedule.

When is it too late to start pepper seeds?

The longer your growing season (number of frost-free days), the more wiggle room you have.

It’s important to note that the number of days to maturity means the timeline between planting seedlings in the garden and harvesting your first peppers. It doesn’t include germination time and inside growing time. Also, since peppers ripen their pods in small flushes instead of all at once, you’ll want to give yourself enough time for multiple harvests to get the most out of your plants.

For a pepper variety that takes 90 days to mature, aim to transplant seedlings at least 130 days before your first fall frost date. That way, you’ll have at least a month of harvesting time. If you’ll be cutting it much closer than that starting from seed, it’s probably best to pick up some seedlings from the nursery this time to ensure you’ll get plenty of peppers.

What if your growing season isn’t long enough?

Folks who have a short growing season can grow peppers in containers like buckets or grow bags to work around the weather. This allows you to carry your pepper plants inside at night when there’s a threat of frost, meaning you can extend your harvest later.   

Soil and Containers for Pepper Seedlings

Soil– For germinating pepper seeds, use a soft, soilless seed-starting medium like peat moss or coco coir. Most bagged seed-starting blends you can easily find at garden or hardware stores work fine for pepper seedlings. If you want, you can add a little perlite to the mix to improve aeration and drainage, but this is optional.

Since pepper seeds are small and the roots are delicate, it’s especially important to avoid coarse potting soil, rough compost, or any soil blend containing “forest products.” Starting in potting soil that’s full of wood and bark bits is a common cause of failed pepper seedlings.

Containers- Pepper seedlings grow best when started in small pots or cells no more than two or three inches deep. This does mean you’ll need to move them up to bigger pots later, but the benefits of doing it this way are worth the hassle.

Here’s why:

When they’re first starting out, pepper seedlings’ tiny, slow-growing roots can’t deal well with waterlogged soil. That big chunk of soil in a container like a solo cup will stay overly soggy for a lot longer than a 2-inch cell after watering, which makes it very easy to accidentally overwater baby pepper seedlings.

Since small cells drain and start to dry out faster, they’re much more forgiving of watering a little too much. Plus, having your pepper seeds in small containers can be helpful for keeping the soil at the right temperature for germination, which we’ll get to in the next section.

Whatever containers you use to sow pepper seeds, make sure they have good-sized drainage holes at the bottom to keep water from sticking around longer than it should.

Read this post for more tips on choosing the best soil, containers, and other supplies for your seed starting setup: No-Fuss Supply List for Indoor Seed Starting.

Germination

To germinate pepper seeds, sow them 1/4 inch deep in your pre-moistened seed starting mix. Good soil contact is important for seed germination. To remove any air gaps, gently pat down the soil surface, then give it a good soaking with a fine-mist spray bottle to settle everything in.

Pepper seeds are notorious for being stubborn about sprouting. But really, they have excellent germination rates, at almost 100% with the right conditions. The key is making sure the soil is warm enough, and peppers like it extra warm.

For fastest germination, the soil temperature should be between 70 and 80 degrees Fahrenheit. At this temperature, pepper seeds should germinate within 7 to 10 days (though I’ve seen it happen faster). Super hot pepper varieties, like Ghost Pepper or Trinidad Scorpion, are known for taking longer than other types. I don’t start worrying about those until it’s been over three weeks.

How to Keep Soil Warm for Pepper Germination

There are a couple ways to get your seedling soil up to temperature and keep it there for pepper seeds:

The Fridge Top Method

Most likely, you already have a warm enough place to germinate most pepper seeds somewhere in your house. Some good options might be on top of your fridge, or maybe a tall cabinet or high shelf in a heated room. Usually, tucking your seedling trays up in a warm place like this works fine. Just keep an eye on them and watch for sprouts, since they’ll need to go under grow lights as soon as they break the soil.

Seedling Heat Mats

A seedling heat mat will provide the most consistent warmth for germinating peppers, especially if your house gets drafty or chilly at night. Heat mats will also give you better germination for hot pepper varieties, which have more trouble sprouting if the soil temperature drops below 70 F.

For the heat mat to be effective, you’ll need to have your seeds planted in small seedling cells. Seedling heat mats put out gentle heat, and it won’t reach the top portion of the soil if the containers are too big.

Also take your seedling trays into account, here. While a thick, heavy-duty seedling tray makes for easy handling and carrying for bigger seedlings, it’ll block most of the heat mat’s warmth when you’re trying to germinate them. I advise stopping by the dollar store and finding the thinnest, flimsiest trays available to use with your heat mat!

Most of the time, it’s best to remove the heat mat once the seeds sprout. However, if your growing area gets chilly at night, you can leave the heat mat on for extra warmth as long as you have a soil probe thermostat controlling the heat. Too-warm soil once seedlings are growing may cause them to get leggy, so you’ll want to make sure the soil temperature stays below 75 F. I like this seedling heat mat and thermostat combo.

Humidity Domes

A humidity dome is another tool you can use along with a heat mat to help pepper seeds germinate. The dome fits on top of the seedling tray, trapping in moisture to prevent the soil from drying out and retaining warmth from the heat mat. In a chilly room, a dome can boost soil temperature quite a bit higher than a heat mat alone.

The problem with humidity domes is that they’re bad to create excessive moisture, and conditions like that can lead to damping off disease and seedling death as seeds are germinating. Using a dome requires careful watering and daily observation to avoid moisture issues, but they can be helpful in some situations (for instance, in a particularly dry house).

Read this post to learn more about using seedling heat mats and humidity domes: Using Heat Mats and Humidity Domes for Seed Starting: Everything You Need to Know.

Will pepper seedlings sprout without added heat?

Most pepper seeds will germinate at temperatures below that ideal range, but they’ll take several weeks to a month. You can get away with starting seeds earlier to make up for lost time, if it’s not practical to keep the soil warmer than that. Just keep in mind that soil temperatures below 60 may cause poor (or zero) germination in peppers, since the seeds are likely to rot before they get around to sprouting. They really do need a little warmth.

Don’t forget to keep the soil moist!

The trick with germinating seeds that need warm soil is that it’ll dry out quite a lot faster than room temperature soil. Dry seeds aren’t going to sprout! Don’t forget to check on your trays once or twice a day to make sure the soil is still damp, misting them as needed.

When you’re using a heat mat, the heat will often dry the soil from the bottom up. Pick the containers up every now and then and check the bottoms. If they get super dry, place them in a tray of shallow water to re-wet them without displacing the seeds. Keeping the soil damp near the bottom will encourage roots to grow downward once the seeds germinate.

A quick watering hack for pepper germination: make sure the water is room temperature or just a little warmer, since cold tap water can lower the soil temperature quite a lot. I usually continue to do this for peppers even after they’ve sprouted, until they’ve grown a little bit.

Stuck Seed Coats

Peppers are prone to having trouble shedding their seed coats when they sprout. Seedlings with a stuck seed coat will emerge looking as if they’re wearing a little seed hat. Sometimes, the seedling will grow and develop anyway. Every now and then, though, the stuck seed coat blocks too much light from the leaves, resulting in seedling death.

Keeping the soil properly moist during sprouting reduces the number of “seed hat” seedlings you’ll get, but you’ll probably have a few regardless. To help the seedlings free themselves, spray the seed coats with water several times a day to soften them. I also like to plant two seeds per cell so I can thin out any sprouts with a badly stuck seed coat.

Watering Pepper Seedlings

I see the claim pop up frequently that pepper seedlings need extra dry soil once they’ve sprouted, to the point you should even let them start to wilt before watering again. I don’t think this is good advice. Peppers may like well-drained soil, but they’re not cactuses, y’all.

While mature pepper plants are pretty drought tolerant, letting your young seedlings get too dry between waterings can cause plant edema, or tiny blisters on the leaves. Underwatered pepper seedlings may also start to flower early. Blooming is a sign of stress in seedlings, and stressed plants will have growth setbacks.  

Don’t overthink it and get tempted to deprive your seedlings of water. All you need to do is allow the soil to dry some between waterings, and they’ll be fine.

For more about the best practices for watering seedlings, check out this post: How to Properly Water Your Indoor Seedlings.

Two Keys to Awesome Pepper Seedlings: Light and Fertilizer

One of the small challenges with growing pepper seedlings is the fact they take such a long time to reach transplanting size, compared to the usual 4-6 weeks most other annual veggies take. Seedlings kept indoors in small pots for this long can get a little peaked. Thankfully, there are a few tricks to keep them green and happy until it’s time to transplant them. 

Light Exposure

Seedlings that get uneven or not enough light will get pale and leggy, which is why it’s important to keep your seedlings under grow lights from the time they sprout. Like most seedlings, peppers need bright, overhead light for 12 to 16 hours per day.

The problem with grow lights, particularly the budget friendly kind, is that they can’t replace real sunlight. Seedlings under artificial light for longer than a few weeks may develop a pale color as they start to put on more growth. This happens when they’re not able to pull enough energy from the grow lights to produce plenty of chlorophyll.

Since they need to be grown indoors for quite a while, pepper seedlings benefit from sun-bathing sessions early on. I start taking mine out for a few hours a day once they’re about a month old, as the weather permits. You’ll be surprised how your pepper seedlings will green up and glow almost overnight once they get some real sunlight.

Pepper seedlings can go outside to enjoy the sun whenever temperatures are in the upper 50s or higher. When you first introduce pepper seedlings outdoors, start by placing them in a mostly shaded area with a bit of filtered sunlight for an hour or two the first few days. Then, gradually move them into brighter light for longer periods of time. Seedlings raised indoors will get sunburned if you don’t acclimate them slowly.

Fertilizing Pepper Seedlings

Most annual vegetable seedlings benefit from a little fertilizer, but it’s especially important for pepper seedlings, since they’ll be in containers for a longer time. You’ll need to start feeding your pepper seedlings with a water-soluble fertilizer once they have a fully developed set of true leaves.

This post right over here has more tips for fertilizing indoor seedlings: How to Fertilize Seedlings (and Why You Should)

Potting Up

When you start peppers in small seedling cells, they’ll need to move into larger containers when they get bigger. The new pots should be at least 4 inches deep. Solo cups work great for potting up, and they can be re-used for at least a few seasons. For soil, I like to use a blend of 1:1 seed starting mix and all-natural potting mix.

As a general rule, potting up can be done once seedlings have a few sets of true leaves. At that point, the baby plants should have a nicely developed root system.

Potting up is best done a day or two after you last watered your seedlings. Soil that’s slightly damp holds together better than wet or very dry soil, which makes it easier to slide the little root balls loose. Be careful not to damage the stems when potting up, but don’t stress it. Pepper seedlings aren’t too picky about being handled.  

Pepper Seedling Problems

Some common issues you might notice with your pepper seedlings are root rot, plant edema, leaf curl, and nutrient deficiency.

Root Rot

Pepper seedlings in containers are prone to root rot if the soil stays too water-logged, particularly when they’re still small. Signs of root rot in pepper seedlings are wilting, drooping leaves even when the soil feels wet, yellowing, leaf drop, and sudden seedling death.

There’s not much chance of saving pepper seedlings with root rot, so the best course of action is to prevent it. Again, starting your pepper seeds in small cells rather than large pots greatly cuts down on the chances of root rot happening.

Once they’re potted up into the next size container, practice feeling pot weight to decide when watering is needed. Heavy pots are still damp enough, even if the soil looks dry on top. You’ll find they get noticeably lighter as they start to dry. It’s not an exact science, and older pepper seedlings with well-developed roots are a lot less likely to develop root rot.

Plant Edema

Seedlings with plant edema develop little blister-like bumps on the leaves, which can turn into necrotic (brownish) spots in bad cases. Sometimes, it may cause a few leaves to drop. Plant edema happens when your seedlings’ roots take in water faster than the plant can absorb and use it. The excess water causes cells in the leaves to burst.

Some possible causes of edema in pepper seedlings are poor air circulation, not enough light, and water stress. If you see signs of edema, you can increase airflow by running a gentle oscillating fan on the seedlings for a few hours a day (this will also help them develop strong stems). Make sure to water your seedlings before they start wilting, and avoid watering at night when the grow lights are off, since light helps the leaves transpire water. Edema may also be a sign your seedlings could use some real sunlight.

Pepper seedlings raised indoors are overall prone to edema, but they’ll usually outgrow it once they’re outside in the garden.

Leaf Curl

Curling, rolled, or wacky leaves is another common concern with indoor pepper seedlings. Leaf curl can be the result of over or under watering, too-cold nighttime temperatures, or some other little stress factor the plant is experiencing.

A lot of the time, the cause of leaf curl in pepper seedlings is a total mystery. I see it happen with a handful of mine almost every year. Even if it looks pretty bad, it’s not usually a sign of any critical problem. Just like with the edema, the seedlings will likely outgrow whatever is causing it once they’re transplanted outside.

Nutrient Deficiency

If your pepper seedlings’ lower leaves suddenly turn an off color, like yellowish or even purple, they’re just ready for a dose of diluted liquid fertilizer. Pepper seedlings can quickly bounce back from a nutrient deficiency as soon as you feed them. The affected leaves won’t turn green again, but new growth will be healthy.

Sometimes, seedlings that are simply pale (not yellow or purple) might just need some real sunlight.

Pepper seedlings can be transplanted pretty small, once they have two or three sets of true leaves, as long as the threat of frost is over and nighttime temperatures aren’t dropping too low. Read this post to learn about caring for your pepper plants beyond the seedling stage, including the best time to transplant and watering and fertilizer needs: How to Grow a High-Yielding Pepper Patch in Your Garden.

Even though they require a bit of extra care to start from seed, peppers are truly a low-maintenance summer garden crop. They don’t need much attention at all, aside from regular pepper picking to keep them producing. They’re also one of the most fun to grow, since they come in so many unique shapes, sizes, colors, and flavors. Once you get started with them, you’ll want to expand your backyard pepper patch every year with new varieties to enjoy and share.