A pepper is a perennial shrub in the nightshade family that most gardeners kill every autumn. Its fruit is a berry, its flowers carry both sexes, and its heat sits in the placenta rather than the seeds. Those four facts explain more grower problems than any fertilizer chart, so start there.

Where peppers sit in the plant world

Capsicum belongs to the Solanaceae, alongside tomato, potato, eggplant and tobacco. Five species carry the cultivated crop. Chromosome counts split the genus: all five domesticates share 2n = 24, while roughly ten wild species run 2n = 26, and that difference is one reason some crosses never take.

  • C. annuum: bell, jalapeño, cayenne, poblano. Widest adaptation, fastest to fruit.
  • C. chinense: habanero, ghost, the superhots. Slow germination, long season, high heat demand.
  • C. baccatum: the ajis and Bishop's Crown. Tall, sprawling, marked by yellow or green spots on white petals.
  • C. frutescens: tabasco, malagueta. Upright pods, compact frames, humidity tolerant.
  • C. pubescens: rocoto and manzano. Black seeds, hairy leaves, purple flowers, cool tolerance.

Wild species such as C. chacoense, C. eximium, C. cardenasii and C. flexuosum sit outside the crop but carry traits breeders want, including cold tolerance and unusual capsaicinoid profiles.

Seed and germination

Peppers are dicots, so two cotyledons open first and the true leaves follow. The radicle emerges ahead of the shoot. Temperature governs the whole process: germination peaks near 29 °C (84 °F) and falls off above 30 °C, which is why a mat that runs hot costs you seedlings rather than saving time. Alternating regimes of 15/27 °C or 15/30 °C break dormancy in seed from all five species.

Wild types and slow chinense lines carry physiological dormancy. Soaking, scarification and gibberellic acid all shorten the wait. Published pepper work used GA₃ at 400 ppm, and concentrations above roughly 400 ppm added no further germination. The GA₃ guide covers the mechanics.

Structure above and below ground

Roots anchor the plant, take up water and nutrients, and form mycorrhizal associations that improve phosphorus uptake. Stems branch at nodes; the branching pattern sets the shape and therefore the support you will need. Leaves photosynthesize and exchange gas through stomata. Trichomes, the surface hairs, cut moisture loss and slow small pests, and they cover C. pubescens thickly enough to give the species its name. For a labeled walkthrough, see the plant anatomy guide.

Flower biology

Pepper flowers are perfect: stamens and pistil sit in the same bloom. Descriptions of the genus give a white corolla with five to seven lobes, five to seven stamens, and a calyx with five teeth. Five is the usual count. Each flower stays receptive for only two or three days. Peppers self-pollinate readily, and vibration from wind or a bumblebee lifts fruit set further. Flowers whose stigmas sit above the anthers outcross at much higher rates than flowers where the two overlap, which is why some varieties stray far more than others. The flower guide by species shows the differences.

Will my peppers cross-pollinate in the garden?

Often, yes. Peppers self-pollinate as a rule, but measured outcrossing in C. annuum runs as high as 91 percent where bee traffic is heavy, so a mixed bed produces seed you cannot trust. Crosses within the Annuum complex, including annuum with chinense, succeed routinely. C. pubescens sits apart: it crosses with almost nothing, and several published attempts fail at pollen tube growth or embryo development. Bag the blooms or isolate by distance if you plan to save seed.

Fruit development

The ovary becomes a berry after fertilization. Wall thickness, shape, ripe color and flavor all trace to genetics that differ sharply across species and cultivars. Capsaicinoid glands develop in the placenta, so the seeds only acquire heat through contact with that tissue. Ethylene drives the color change at ripening; auxins direct root and shoot growth and matter most right after transplant; gibberellins govern elongation and flowering.

Why do pepper plants drop their flowers?

Heat, most of the time. Texas A&M puts the threshold at daytime highs much above 90 °F combined with nights above 75 °F, and nights below 55 °F cause the same failure from the other direction. Pollen loses viability, fertilization fails, and the plant sheds a bloom it cannot use. Shade cloth and steady soil moisture carry a planting through a heat wave; fertilizer does not.

Life cycle and what to do with it

Peppers are perennial shrubs in frost-free climates and annuals everywhere else by accident of winter. Overwinter one indoors and the second season starts from an established root system and a woody frame, so flowering begins weeks earlier. That payoff is largest for chinense and baccatum lines in short seasons, where the plant spends most of a first summer just getting to size. The overwintering guide covers the cutback and the light.

Sources & Further Reading