Pepper is an annual herbaceous plant, with limited growth. Height and growth depend on culture and cultivar conditions. The main stem ramifies between 10 and 40 cm in two or three branches. Secondary stems develop from buds, fruits grow on these stems.

Stems and branches are important structural support elements for leaves, flowers and fruits. They are involved in transport of xylemic and phloemic sap, phyto regulator synthesis and other metabolic functions. Pepper has a deep tap root with a lot of fasciculate roots which grow horizontally within a radius of 30 and 50 cm.

Leaves are alternate, entire, lanceolate, hairless and bright green with a sharp tip.
Flowers are white, small and solitary at each node (occasionally fasciculate) with declined pedicels. Corolla is milky white. Calyx is formed by welded sepals in single piece. Sepals harden until fruit ripening. Flowers are mostly autogamous. There is a low percentage of allogamous flowers.

Fruit is a hollow berry with a bright and even surface. They are divided by 2 or 4 incomplete walls, which join on the base over placenta. Varieties consumed fresh have different shapes and colours (red or yellow at ripening). Some varieties are hot flavour because of the presence of capsaicin.

Pepper has numerous circulars, flat shaped, yellowish seeds. They are attached to a peduncle extension in the inner side of the fruit. Seeds can germinate after 3 or 4 days.

 

Pepper plant development is influenced by different factors, the main ones are:

Temperature: This culture needs increasing temperatures from first growth stage to fruiting, sudden changes in temperatures between day and night are not well tolerated.
Average temperatures of between 18 - 22° C are necessary to obtain good vegetation and plentiful harvests. The optimal temperature is about 20 - 25 °C by day and 16 -18 °C by night. Vegetative disorders like plant hardening and fall of flowers are produced when difference between day and night temperatures is too great.

The optimal temperature for seed germination is between 20 and 30 °C. Seeds do not germinate when the temperature is below 13 °C or over 37 °C. During germination and plant development the temperature should not be less than 18 °C because this will seriously affect plant productivity (first fruit stage appears during seedbed stage).
Plant growth slows down when temperature is below 15 °C. At 10 °C the growth shuts down and temperatures below 0 °C could generate freezing damage. Sub-optimal fertilization occurs, principally in dry climates, at temperatures above 35 °C.

If environmental moisture is high, pepper plants tolerate temperatures over 40 °C, if not, it will produce vegetative shut-down with fall of flowers, and small fruits and leaves. Thick skin (peel) varieties peppers are more temperature exigent than thin skin ones.

Humidity: Optimum relative humidity is between 50 - 70 %, during normal conditions of temperature. If relative humidity is over 70%, cryptogamic diseases can occur, which require the use of systematic chemical treatments.

At the early development stages pepper plants need higher relative humidity than at later stages. Efficient ventilation is required during flowering and fruit set to shut down vegetative growth, and increase production.

Brightness (Luminosity): This culture is light-demanding throughout the vegetative cycle, particularly during flowering. Flowers are weaker when light is low during flowering. Light shortage results in poor plant growth, with internode and stem lengthening, resulting in plants not being able to support a big harvest.

Photoperiod: Pepper fruiting is reduced in autumn compared to spring, due to the influence of increased humidity, and reduced temperature and photoperiod length on vegetative growth and fruit production.
Flowering seems more conditioned by temperature and light than photoperiod length. However, during autumn, with favourable temperature and light conditions, there seems more falls of flowers than in spring.

Ground demanding: The most optimal soils for pepper cultivation are sandy, deep, rich, and well drained, with organic matter content of about 3 - 4%. The optimal pH values are about 6,5 and 7, although pepper can withstand mildly acidic conditions, to about 5.5 pH. In sandy soils, the pH values may be around 8. In irrigation water optimal pH ranges from 5.5 - 7. Salty (saline) soils are not suitable for pepper cultivation, because plant development is reduced, which affects fruit size and crop yields.