1. Why Bell Peppers Are Not Spicy Even Though They Are Chili Relatives
Bell peppers are a type of green pepper and belong to the same genus as chili peppers. As a general guide, large, thick-fleshed peppers weighing over 100 g (about 3.5 oz) are often called bell peppers, though this is not a strict rule [1]. Chili peppers are spicy because they contain a substance called capsaicinoids. Research from Kyoto University describes a gene called pAMT as a "faucet-like gene." The study reported that if the position where another sequence inserts itself into the gene changes, the "tightness" of the faucet changes, altering the spiciness [2]. Note that this specific study did not examine bell peppers directly.
Another paper explains that spiciness is lost because the enzyme that creates capsaicin, controlled by the Pun1 gene locus, stops working. In non-spicy varieties like green peppers, several ways for this gene to stop working are known [3]. The materials for this article do not specify which type bell peppers use. The key point is that bell peppers are not made non-spicy by changing how they are grown. So, what is different about them compared to green peppers?
2. Why Waiting for Bell Peppers to Change Color Takes About 2 Months
According to the Iwate Prefecture manual, green peppers are harvested about 3 weeks after flowering. In contrast, bell peppers take more than 50 days after the fruit sets to become colored and ready for harvest [4]. In terms of time after flowering, this is 50 to 70 days. Harvesting happens when the fruit is about 80 to 90 percent colored [4]. This suggests that waiting for the color to develop adds to the time before harvest.
Temperature conditions also matter while waiting. A suitable air temperature for fruit setting is 17 to 30°C (63 to 86°F), and soil temperature is around 20 to 25°C (68 to 77°F). Coloring progresses most rapidly at 20 to 25°C (68 to 77°F). If the temperature drops below 12°C (54°F), the growth of stems and leaves stops [4]. This means it is a long period of about 2 months where progress is difficult if it is too cold or too hot. During this time, how do growers care for the plants to keep the fruit growing? Note that comparing green peppers and bell peppers can be tricky because the starting points for measurement (flowering vs. fruit setting) are not always aligned, so the "more than twice as long" claim should be read with caution.
3. Why Red, Yellow, and Orange Bell Peppers Are Not Always the Same Fruit Ripening
The red, yellow, and orange peppers in stores are not always the same fruit ripening from yellow to orange to red. In a variety comparison test in Ibaraki Prefecture, varieties are separated by color, such as red varieties, yellow varieties, and orange varieties. High-yield and high-quality varieties are reported for each color. For example, "Kupra" and "Plenty" are red, "Confetti" is yellow, and "President" is orange [5]. Fruit color differs by variety, and some varieties do change color as they ripen. Red peppers are closest to full ripeness and are said to be the sweetest. Yellow peppers have a refreshing sweetness with a bit of acidity, and orange peppers are in between [1]. However, not all varieties progress from yellow to red; the final color depends on the variety.
4. How Bell Peppers Are Grown in Greenhouses Without Soil
The Iwate Prefecture cultivation manual describes soil-free hydroponic cultivation. Seedlings are planted in rock wool, which is a medium made from fibrous rock. Since rock wool itself contains no nutrients, plants must be grown using nutrient solutions. It drains well and is less likely to become overly wet. Three plants are planted in one medium, with 40 cm (about 16 inches) between plants [4].
About one month after planting, branches are guided using hanging strings. The basic method is a "4-branch training," starting with the main branches shaped into a V [4]. The lifespan of a leaf is said to be about 120 days, and leaf pruning (removing old leaves) begins about 3 months after planting [4]. Because it takes more than 50 days for the fruit to color, care such as hanging branches, arranging leaves, and providing fertilizer dissolved in water continues for months. Is it possible to make the fruit color faster?
5. How Light Can Shorten the Wait for Partly Colored Bell Peppers
Manuals from Iwate Prefecture mention post-harvest ripening techniques. Fruit that has colored about 10 percent on the plant is harvested. If LED light is applied continuously for 24 hours in a room at 20°C (68°F), the fruit can reach 90 to 100 percent coloring in about 3 to 5 days [4]. If the light is weak, coloring does not progress. This is not a claim that "any light makes anything red." The condition is that the fruit must already be about 10 percent colored. The finishing touch of coloring is done in a room after harvest, not on the plant.
6. How Much of Japan’s Bell Pepper Supply Was Imported in 2016
According to the Agricultural and Livestock Industry Corporation (ALIC), in 2016, Japan's bell pepper supply was 40,488 tons (89.9%) imported and 4,565 tons (10.1%) domestic [7]. Japan first imported bell peppers from the Netherlands in 1993, and about 80% of import volume was from South Korea. These figures are for that specific year and are not the latest data [7]. Comparing yield per 10 ares (about 0.25 acres) in large greenhouses, Japan produced about 14 tons, the Netherlands about 30 tons, and South Korea about 25 tons. Japan's yield was about 47% of the Netherlands and about 56% of South Korea. These figures apply to large-scale greenhouses in Japan, not the average for all farmers [7].
In South Korean production areas, environmental control using ICT (Information and Communication Technology) is used, and red, orange, yellow, and green peppers are shipped year-round [8]. In Japan, examples of large-scale production by companies from other industries, such as construction firms, have increased [7]. The figures show differences in cultivation time and yield, but do not explain why yields differ.
7. How to Tell Bell Peppers and Green Peppers Apart at the Store
You can look for the country of origin at the store. Check the label on the bag or sticker of the bell peppers at the supermarket. In the 2016 ALIC data, about 80% of imports were from South Korea. You can check with your own eyes if this is still the case today. You can also weigh them. Buy one bell pepper and one green pepper and compare their weight using a kitchen scale. Do they fit the 100 g (about 3.5 oz) guide? If you cut the fruit open to see the inside, ask an adult to use the knife for safety [1]. If you want to read more, the Iwate Prefecture "Bell Pepper Cultivation Manual" and the ALIC report "Bell Peppers in South Korea" are available in Japanese [4].