Question
I live near Milwaukee, and am in my sophmore year of gardening on the same plot.  I am growing a variety of peppers, and some of the varieties are showing severe yellowing of the leaves, with only the recent uppermost growth being green. The banana, cherry bomb and green peppers have the worst yellowing, while my jelepeno plants look incredible and the thai giant hot, and chili peppers are also doing well. I did mulch the plants with a mixture of grass clippings, shredded leaves, and composted (store boughten) cow manure, and the plants are in slightly raised mounds. I added a medium-large amount of leaves and grass clippings to the garden in early winter, and tilled it in this spring. What could be causing this, and should I remove the flower buds and/or yellow leaves from these plants.

Answer
Brian, yellowing of leaves is almost always caused by a lack of nitrogen and magnesium in the soil.  Normally this is a result of the nutrients being leeched from the soil due to excess water.  Only give the plants 1" of water per week.  However, it may simply be that the plants require an application of fertilizer high in nitrogen to get past the problem.

Normally I would not recommend a high nitrogen application for peppers ot tomatoes.  This will usually result in lush foliage at the expense of a strong harvest.  However, you need to get the plants healthy again, so this is definitely an option.

One other thing that has worked for me in the past is applying epsom salts to my pepper plants.  Epsom salts supplies magnesium and calcium and is absorbed by the leaves for a quick recovery.  You may want to use this as a foliar spray (3 tbs. per gallon of water) and then apply a granular slow release fertilizer high in nitrogen.

Note: I would remove the flower buds this one time in order for the plants to concentrate their energy solely on the foliage.  You still will have plenty of time for a fruitful harvest.

Have a good holiday.

Regards,

Mike