Why Won't My Peppers Turn Red?

You have a plant full of glossy green peppers that seem to have stopped, refusing to turn red, yellow or orange. It is one of the most common pepper frustrations, and the reassuring truth is that the usual cause is simply that they need more time and warmth than people expect. Ripening a pepper to its final colour takes patience. Let me explain what is going on and how to help them along.

Ripening simply takes a long time

The biggest reason is patience. A pepper takes a long time to go from full-sized green to fully ripe colour — often three to four weeks or more after reaching its mature size. Many growers expect colour too soon. Green peppers are simply the unripe stage of fruit that would eventually turn red, yellow, or orange; if you wait, most will get there. So if your peppers are full-sized and firm but still green, the first answer is usually just to give them more time on the plant.

Warmth drives the colour change

Peppers need consistent warmth to ripen, and ripening slows or stalls when temperatures are too low. Late in the season, as days shorten and nights cool, ripening can grind to a halt, leaving you with green fruit. Conversely, extreme heat can also pause the colour change temporarily. The sweet spot is steady warm conditions. Keeping plants in the warmest, sunniest spot and protecting them from early-autumn chill helps the fruit finish colouring. A run of warm days often brings a whole flush of peppers to colour at once.

Don't let too many fruit stall the plant

A plant carrying a heavy load of green fruit sometimes seems to pause, putting energy into holding all the fruit rather than ripening any. Harvesting some peppers at the green stage — they are perfectly edible green — can free the plant to ripen the rest. Easing off high-nitrogen feed late in the season also nudges the plant from leafy growth toward finishing its fruit. And make sure the plant gets full sun, which powers ripening.

The finish-indoors trick

Here is the grower's rescue, especially at season's end. Peppers will continue to ripen off the plant if they have already started to change colour or are fully mature green. Pick them and leave them at room temperature, ideally near a banana or apple, which give off ethylene gas that speeds ripening — the same trick used for tomatoes. When frost threatens and you still have green peppers, harvest them all: the more mature ones will often colour up indoors over days to weeks, and the rest are delicious used green. Never refrigerate peppers you want to ripen, as cold stops the process.

The takeaway

Most "won't turn red" peppers simply need more time and warmth. Be patient, keep plants warm and sunny, harvest some green fruit to free the plant, and finish mature green peppers indoors near ripening fruit if the season is ending. Do that and your green peppers will reward you with their full, sweet, coloured ripeness.