Pepper Plant Problems

May 3, 2024 6:15 PM

I'm new to gardening. I was growing some pepper plants in containers. They were doing great until they weren't. Their leaves started growing in curly with black and grown streaks. Now they are falling off. What did I do wrong?

I bought 3 different kinds of pepper plants: a serrano chili, a fresno chili, and a lemon drop pepper. They were each growing in three big, separate pots. Planted in potting soil from the gardening store. In the month since I got them, I have watered them weekly and fertilized them once. I found aphids on the lemon drop, and sprayed them all with a neem oil/soap/water mix and that seemed to take care of it. I live in the Bay Area, and the weather has been sunny and warm lately. The peppers are growing in full sun.
They were doing so well- one was even about to blossom. Then one by one, they all seemed to succumb to the same fate:
The leaves started to become curly
Black/brown streaks appeared on the leaves
Here is a picture
Now, all the leaves are falling off and they are beginning to die. I've tried googling, and can't pinpoint exactly what has gone wrong. Also, I have other potted plants in the same backyard (herbs, tomato, a lemon tree) and they are all doing great - this is only impacting the peppers
Does anyone have any ideas?

posted by firemonkey to Home & Garden (9 answers total)

Watering weekly might not be enough given the conditions. Alternatively you can also run into issues putting small plants into too large a pot which lets them sit in moisture too long.

Based on the pics though they look pretty thirsty, I'd give them water twice weekly or whenever an inch or so down feels dry.
posted by Ferreous at 7:04 PM on May 3 [2 favorites]

According to Pepper Geek, the curling leaves could be due to overwatering, edema, or being root-bound.
posted by mezzanayne at 8:38 PM on May 3

To me those look thirsty. If the weather has gotten warmer in the past week or two, you may need to water more often. A bigger plant will also pump more moisture out of the soil and into the air, but that can be counterbalanced by the larger root volume having access to a larger volume of soil moisture.

I find that potting soil designed for houseplants dries out faster than garden soil/compost, because houseplants usually have the problem of being too wet since they're not exposed to as much sun and air circulation as outdoor plants. You may want to throw in some compost to help hold more moisture and give the little guys a steadier nutrient source.
posted by heatherlogan at 9:05 PM on May 3 [2 favorites]

The fact that the younger leaves are paler/yellower makes me also think lack of nitrogen.
posted by heatherlogan at 9:07 PM on May 3

Hard to tell exactly from the photos, but this could be mosaic virus, which is spread by sucking insects, and/or over watering (the curling leaves can be symptoms of both over watering and viral disease).
I would be certain to water only when the top inch or two of soil around the root ball is dry, and make sure there are no sucking insects like aphids or thrips. Over watering issues will go away when the problem is resolved- the plant have fine new growth. Mosaic virus is incurable however.
It can be in the soil you used or in non-resistant pepper seeds, so do not re-use this soil if the problem does not resolve, and wash your hands before working with your other vegetables, especially tomatoes.
posted by oneirodynia at 10:12 PM on May 3 [2 favorites]

Here's why people are saying overwatered and underwatered, a lot of the symptoms are the same. I personally think those are underwatered, but definitely agree with Ferreous and oneirodynia about checking the soil to tell when to water and heatherlogan about getting some compost added to the soil. Peppers are sensitive to overwatering in general, but once a week isn't much for peppers getting a lot of sun.

I'd say to water early in the morning if the first 2 inches of soil feel dry, add some compost to the soil, and also some mulch on top to keep the moisture in. Plants in containers dry out more quickly than plants in the ground, so keep that in mind when researching "conventional" wisdom about watering peppers.
posted by Eyelash at 2:53 AM on May 4 [1 favorite]

Once a week watering in full sun may be too infrequent. I'm a newbie gardener and when I was growing cherry tomatoes in a container I ended up watering every other day/every third day (I stuck my finger in the top two inches of the soil and checked how dried out the soil was) AND adding some vegetable fertilizer (aka the nitrogen mentioned above, I used Dr. Earth fyi). Adding some mulch to the top of the soil is a great idea too, it helps modulate the swings of temperature and moisture. Lastly I see that your containers are black plastic, which means that sun will heat them up faster and contribute to water evaporation.
posted by spamandkimchi at 9:32 AM on May 4 [1 favorite]

Peppers don't like to sit in wet soil, but they are pretty heavy drinkers and they're very hungry - I would recommend topping up your pots with some compost and giving them a good feed. Feed/compost marketed as being for tomato plants will work well. Even in the UK, when it's hot I water my tomatoes and peppers daily and generously.
posted by In Your Shell Like at 1:03 PM on May 4

For the past decade or so I've been growing several varieties of peppers in containers.

First, what is the size of your containers? It may sound counterintuitive, but the smaller the container, the more frequently you have to water (and fertilize). Regardless of the size, watering once a week is not frequent enough for peppers in containers. Also, when you water, how deeply are you watering them? Just getting the surface wet will not be enough, water has to reach the roots.
I am in USDA Zone 8a (7b prior to 2023), growing in full sun, and I water pepper plants daily early in the morning, and sometimes twice a day during hot, dry spells.

Second, what kind of potting soil did you get? If it's the same as for your other containers, then the potting soil likely is not the culprit, but the quality of the potting soil can matter. Store-bought potting soil can sometimes have contaminants or pests that damage and kill plants. Also, how well does the soil drain? Is it just soil or is there some vermiculite or perlite mixed in?

Third, what was the fertilizer you used? The kind of leaf bubbling seen in your pictures can also happen due to calcium and magnesium deficiency. The ph of the soil can affect the ability of the plant to take up calcium in the soil. Fertilizers specifically for tomatoes will typically include calcium in addition to nitrogen-phosphorus-potassium in the appropriate ratios for fruiting. Depending on the plant's growth cycle I've sometimes had to provide Cal-Mag fertilizer separately.

Lastly, your county cooperative extension can be a helpful resource for troubleshooting and growing advice. e.g. University of California Cooperative Extension Contra Costa County
posted by research monkey at 1:32 PM on May 4 [2 favorites]