They demand warm temperatures—not too cool and not too hot, organically rich soil, and even soil moisture—not too little and not too much. Give peppers these optimal conditions and they will produce until the first frost in autumn.
Common mid-summer pepper problems and their cures:
• Bell peppers are small and bitter. Peppers are native to the tropics; they need warm temperatures of 70° to 80°F during the day and 60° to 70°F at night to thrive. They require soil rich in organic matter—add aged compost around plants–that is consistently and evenly moist—water deeply once or twice a week and mulch to conserve soil moisture in dry weather or hot temperatures. If temperatures are too warm or too cool, if the soil is not rich enough or too dry, peppers will not grow to maturity and they will be bitter flavored. One more thing, if the soil has a boron deficiency, peppers can also be small and bitter; have the soil tested.
• Pepper plants grow large but the blossoms fall off–no fruit. Temperatures below 60°F or greater than 90°F will cause pepper blossoms to drop; water stress—soil that is not evenly moist—can cause plants to wilt and blossoms to drop. Keep the soil evenly moist; use a thick mulch of straw or compost to keep the soil from drying out in hot weather. Protect pepper plants from hot temperatures by shading them with shade cloth draped over a wooden frame. Protect peppers from cool temperatures by covering plants with floating rows covers if nighttime temperatures dip below 60°F. Bell peppers least susceptible to stress include Lady Bell, Canape, Green Boy, Ace, and New Ace. Peppers susceptible to heat and water stress include California Wonder and Yolo Wonder.
• Pepper fruits are deformed. Flat or deformed fruit can be caused by exposure to temperatures in the 40°s and 50°sF or lower; low temperatures can inhibit pollination and ovaries may not develop properly. Protect plants from low temperatures by covering them with floating row covers; avoid planting too soon next year; plant peppers on the southside of the garden or next to building where they will be warmed by reflected heat. Two peppers that can withstand cool temperatures are Golden Bell and Staddon’s Select.
• Plants are slow growing, pale green, or dropping leaves. Peppers are heavy feeders; give peppers a boost with a sidedressing of manure tea or a liquid fish or kelp fertilizer. Make sure the soil and soil amendments such as compost contain nitrogen. Add grass clippings or aged manure to compost made from composted leaves. After plants have produced fruit, a sprinkling of bloodmeal around plants will offer a nitrogen boost and increase yield.
• Plants aren’t producing much fruit. The more you pick peppers, the more they will produce. Harvest peppers early and often; you can start picking and eating peppers as soon as they are big enough to eat. The more fruit you pick, the more fruit you will get. (The store of vitamins A and C is highest when peppers grow to full size and about two-thirds of their intended full color–for non-green varieties.)
• Fruits are turning brown and papery. Temperatures higher than 90°F can cause sunscald or sunburn leaving skins burnt looking. When temperatures soar set a wooden support over plants and put shade cloth in place. High temperatures can be moderated with a sprinkle of cooling water in the middle of the day. Place several inches of organic mulch across the growing bed to keep soil moisture from evaporating.
• Plants quit producing in the middle of summer. Bell peppers are sensitive to too much heat; when temperatures hit the 90°sF, plant go dormant to wait out the heat. Once high temperatures subside, bell peppers will begin producing again. Hot peppers will bear all summer no matter the heat.