New-ish gardener here! This year I have planted 5 varieties of peppers in a brand new raised bed in central Arkansas (zone 7b). Fill for the raised bed is 100% compost purchased from a local plant store, with no amendments or additions.

Initially all of the peppers saw slow growth through the cooler, wetter weeks after transplanting, but as it has warmed up most of them have grown quickly. At first 2 of the plants showed signs of strange growth, including new leaves curling, thickening, becoming harder, darkening and areas of new growth looking strange and stunted. Because of the presence of these symptoms only on new growth, I assumed a calcium deficiency. (google image results for "pepper plant calcium deficiency" show at least one result that looks like my plants, but the comments were inconclusive). Several posts here have suggested that ongoing pest damage could cause this, but I have seen very few pests and have preemptively applied neem oil on a couple of occasions.

In the last few weeks, new growth on some of the surrounding plants has started to show some of the same symptoms and now I am not so sure what could be going wrong here. I'm starting to think that it could be one of the following:

  1. Disease (virus, maybe? transmitted between plants via pest)
  2. Deficiency of some nutrient (peppers are growing in compost with no soil mixed in)
  3. Toxicity of some nutrient (I have no idea what the nutrient balance of the compost is)
  4. Presence of herbicide in compost (I don't know the source of the compost)
  5. Environmental factors (Maybe overwatering. Compost retains significant moisture)

I'm trying to determine if any of the above causes are an obvious cause of these symptoms.

In addition, These plants are planted within 5-10 feet of a bed of tomatoes in similar planting conditions, some of which are showing leaf curl which does not resemble this, and a potted ground cherry plant in store-bought potting soil does have similar symptoms.

I've attached some images that should show the affected area of a couple of the plants, as well as a previously healthy plant that is now affected. I can provide any additional photos, including ones of surrounding plants, to help diagnose this.

patient zeropreviously healthy plant Closeup of previously healthy plant

  • What kind of conpost? – Bamboo Jun 16 at 23:46
  • @Bamboo, It's a municipal compost, I believe. I bought it from a garden center. It has lots of organic matter, as well as the occasional piece of random litter. – Joseph Benton Jun 17 at 15:28

If you filled the bed completely using only municipal compost with no soil, that might be the problem. Composted materials of this type are meant for mulching or digging into garden soil; they are not usually suitable for use as a planting medium, especially not in a contained area. If your raised bed is open at the bottom and sitting directly on soil,that's not quite so contained as a raised bed on legs - not sure which you've got, but even so, there is no soil in the raised bed, only the compost. You could try checking the source to see if it's been produced using a hot, aerobic method, which would mean it is suitable for use as a planting medium, but more usually, these are not produced in that way.

The other possibility is there is some contamination from pesticides (usually herbicides) of some sort; this could be present in the compost, or could be caused by spray drift from you or someone else spraying some sort of pesticide nearby. Note that composted materials meant for soil conditioning purposes do not usually cause problems when mixed in with soil in open ground, though some horse manure can sometimes be contaminated with a particular herbicide.

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