Selectively Breeding Pepper Plants

Selective Breeding Fury Pepper Hybrid
Our 2019 attempt to continue selectively breeding our fury pepper (F4 & F5) – originally was an accidental white ghost hybrid

Have you ever had a pepper plant that was "different" in a way that made it one of your favorites – a pepper plant you'd like to grow year after year? Perhaps, it was an accidental or purposely created hybrid. Or, it was simply a traditional pepper cultivar that happened to have larger fruit, better flavor, or a higher yield.

Now what? You could take cuttings to clone the plant. You'd be guaranteed an exact genetic copy, though, cloning attempts don't always root successfully – and overwintering the cuttings potentially creates other issues.

It'd be more convenient to take its seeds and attempt to grow it again next year. The problem is that there's no guarantee the resulting pepper plants will share the desired traits of their parent. That's where the process of selective breeding comes in.

What is Selective Breeding?

Selective breeding has been used by humans for thousands of years. It's the process Native Americans used to turn a grass-like plant into modern day corn. These same early civilizations used selective breeding to domesticate small, berry-like wild peppers into the habanero, jalapeno and many of the other popular varieties we now enjoy. The intertwined processes of hybridization, random mutations, natural selection and selective breeding have produced an estimated 50,000 varieties of chile peppers!

Where hybridization and random mutations introduce newness, it's the processes of natural selection and selective breeding that choose which traits endure.

Simply put, selective breeding is a numbers game – take seeds from parent plant(s) with desirable trait(s) and grow a bunch of plants from them. Evaluate the plants and chose the ones that best express the intended traits to self or cross pollinate. Harvest those seeds and repeat the process. Carried out over several to many successive generations, this process can magnify and lock-in the traits desired.

What's Going On Behind the Scenes?

The original "different" plant that produced the desirable traits, was different due to different genetics (assuming it wasn't due to different growing conditions). The difference in genetics was either due to hybridization, a pairing of rare recessive traits, or random genetic mutation(s). This first generation plant is referred to as F1, or the first filial generation. Seeds taken from this first generation plant will be the second filial generation, or F2. Seeds taken from that generation, are referred to as F3 seeds that'll produce F3 plants, and so on.

The earlier generations of these plants hold genetic differences that may, or may not, express themselves in the seeds taken from their pods – even in the event of self-pollination. Early generations are less likely to consistently produce offspring with the desired traits, and are less likely to do so to the fullest extent. This is especially true for F2 hybrid plants, which theoretically, should have the greatest differences among its siblings. Due to the intricacies of genetic science (which we're not going to dive into), the more generations into the process of trait selection, the more likely those traits are to express themselves within the following generation.

Our research suggests once the selection process is successfully carried through to its 7th generation (F7), the seeds from those plants (F8) should reliably produce plants with the desired traits. By this point, the pepper plant should be a nearly homozygous cultivar – meaning its corresponding chromosome pairs should be nearly identical – and reliably produce seeds that "come true" to produce matching offspring plants.

Things to Keep in Mind

As mentioned, selective breeding is a numbers game. The greater the number of offspring plants grown each generation, the better the odds of maximizing the desired traits. We have somewhat limited space for growing peppers, though we've had good results with 6-10 plants per generation. We now target growing 10 plants per generation, while keeping more seeds on-hand in the event additional plants are needed.

It's also important to note the selective breeding process assumes steps are taken to avoid accidental hybridization. The desired plant(s) should be isolated from other pepper plants to ensure either self-pollination or intended cross-pollination occurs.

To maximize trait expression and to produce hardier plants, the top two, or three, plants of a generation should be crossed with each other. This helps to expand the genetic diversity, which provides for a greater genetic base for maximizing desired traits. Along with color, shape, flavor, heat-level and yield, one should also consider including hardiness, disease resistance and germination rates when grading plants for selection.

Our Experiments with Selective Breeding

Stumbling upon interesting hybrids and attempting to selectively breed them into repeatable varieties is one of our favorite aspects of growing peppers. Below are the two main strains we are currently working to develop.

Fury Pepper (F5 & F4)
Fury Pepper (F4 -> F5)
Fury, F4 pepper w/ F5 seeds

Pictured at the top of this page is our 2019 batch of F5 and F4 fury pepper seedlings. We're currently working with two strains as the F4 variety (F5 seedlings) produced the intended pod-type, but it was less hot than previous generations and had slightly less yield and lower perceived hardiness. The F3 variety (F4 seedlings) had a different pod-type (elongated), but nice heat and hardiness paired with an amazing yield.

This strain originally started as an accidental hybrid of a white ghost, and we believe, a yellow Trinidad scorpion. It's one of our all-time favorite peppers. In previous years, we'd grown four through eight plants per generation, and until last year, always had one express the full set of desired traits to select. We're growing ten this year – five each of F4 and F5 – in hopes we'll have two to cross and propagate.

Peach Pepper (F1)
Peach Hybrid (F1)
Peach hybrid, F1

If we're able to successfully reproduce this pepper, it'll easily be one of our favorites. It's definitely the sweetest and among the juiciest we've ever had. For the first few seconds, it produces almost no heat – but it quickly builds to an almost intolerable level a minute in. It's a smaller plant with medium-sized, peach-colored fruit and sports a decent yield.

This pepper popped up unexpectedly last year (2018). We were attempting to grow a hybrid of a hybrid of an Australian lantern that we believe crossed with our original mystery pepper (got seeds at a chili cookoff and weren't able to identify the variety). We were expecting red, mini, bell-like peppers with good heat, but were pleasantly surprised to get this instead. The prior year, we were growing a flaming icicle nearby and perhaps that mixed in.

We're growing ten offspring plants this year in hopes of getting a matching plant, or two.

Additional Resources