I've been noticing the older leaves on my bell pepper plant have started to turn yellow. I'm growing them from a 1 gallon pot. Any ideas or solutions how to keep them healthy if this is a cause for concern?
A nitrogen deficiency can be indicated by the yellowing of older leaves because nitrogen is mobile in the plant. A sulfur deficiency can be indicated by the yellowing of newer leaves because sulfur is immobile in the plant. The two elements most likely to be leached from soil by excess water is N and S because of the negative charge they have, NO3- and SO4--. Therefore, I would 'think' if over-watering was causing leaching, the whole plant would be yellow (though its hard to make a generalization about every possible soil type).
If the majority of the plant looks healthy and there are just a few yellow leaves at the bottom, its possible there is nothing wrong at all or maybe the soil is slightly low on nitrogen. If there are pieces of wood or leaves in the soil, they could be robbing nitrogen from the soil that the plant might otherwise use.
If I had reason to believe I had a nutrient deficiency in my soil, I would add a fairly dilute water-soluble fertilzer (miracle-gro, etc). I'd expect to see much darker greens in the next day or so after. If it continued to worsen, then I'd suspect some problem with the soil, such as compaction starving the roots of oxygen (water-logging can do the same thing).
I believe Joel is right that peppers are accustomed to arid heat.
Peppers tend to like things on the hotter and dryer side.
I'm having this same problem right now, and was told it was probably nutrient deficiency caused by over watering. I'm trying those fertilizer stakes at the moment since it's been really rainy where I am for the past 6 weeks and doesn't appear to be stopping anytime soon.
What has your rain/watering situation been like? what sort of soil are they planted in?
You may also want to try a compost tea to but back the nutrients the plant may have lost due to the rain. This method has help my yellowing plants turn green again and beef up flower production.
- 2 5 gallon buckets
- 5 cups of Chicken or cow manure compost -OR- worm castings
- Fill a 5 gallon bucket (I use a homedepot orange one) with water and let it sit over night to dechlorinate it. Do not seal the bucket.
- The next day, aerate the water by throwing the dechlorinated water between buckets (like you are making beer).
- Add a shovel full of compost or worm castings (about 1 cup per gallon if you want measurements). Adding this to the water wakes up the dorment micro organisms up.
- Every 2 hours or so, throw the buckets again to aerate and keep the micro organisms alive.
- After 8 hours, water the plants with the compost tea.
NOTE: Any of the aeration steps can be skipped if you would rather buy an aerator to stick in the bucket.