No growing season goes exactly as planned, but it’s still distressing to see any of your chilli plants wilting, and even more so when you have no clue what could be causing it. People’s initial reaction is to immediately give them a good, thorough watering, but if the cause is something else, like too much water, then the well-intentioned gardener could be making the problem worse.
Fortunately, a little troubleshooting can often help determine what the cause is, and in most cases, it’s fixable.
Reasons Why Your Chilli Plant Leaves Are Wilting
1. Your Chilli Plants Aren’t Getting Enough Water
Pepper plants, especially if grown in containers, will dry out faster during hot weather and require more frequent watering.
Check your soil by pushing your finger into it about 1 or 2 inches. As a rule of thumb, if it’s dry at least one inch below the surface, it’s time to water. However, for pepper seedlings, always keep your soil or potting mix evenly moist, but not soggy.
If you notice the soil around your chilli plants is always drying out quickly, it’s recommended to add a good layer of mulch like wood chips, which will shield the soil from the hot sun and slow down evaporation.
2. Your Pepper Plants Are Wilting from Too Much Hot Sun
You might sometimes see your pepper plants wilting in the middle of summer even when the soil is still moist. If you notice this only in the middle of the day while in the early morning or late evening your chilli plant leaves look normal, then it’s likely that high temperatures and too much hot sun are the reason.
Just like us, plants can only uptake so much water at any given time (drink a big glass of water all at once and you’ll feel it sitting in your stomach for a while as it’s getting absorbed into the body). At least 95% of the water plants absorb isn’t even used for growth [PDF] and is lost through transpiration, which is the movement of water from the roots to the leaves where it evaporates through microscopic pores called stomata.
Hot sun will cause transpiration to happen more quickly. However, if it happens so fast that roots can’t keep up, then your pepper plants will suffer a net loss of water and end up wilting even if the soil is wet.
If this is the reason why your pepper plants are wilting, there are a few things you can do. Usually, this type of temporary wilting will resolve itself naturally, but you can either move container peppers to a partially shaded area (especially during a really severe heat wave) or consider using shade cloth over your pepper plants to reduce sun exposure and transpiration.
3. Your Chilli Plants Are Getting Too Much Water (Root Rot)
A less common reason why your chilli plant leaves are wilting, especially if they are mature plants, is too much water. Roots need oxygen, too, and if the soil is constantly soggy, they can start to die and rot away.
Minor root rot is not a problem for large plants and they can recover, but if the cause of root rot is not resolved, it can kill entire chilli plants.
Ensure that your soil is well-draining and not constantly soggy. If you have very heavy clay soil, you can amend it with compost to increase the amount of well-draining organic matter. For mature plants, water when the top inch or so of soil is dry.
This is also a problem in some hydroponic pepper plants without proper aeration or in Kratky-style hydroponics when aerial roots are kept under water.
Chilli seedlings are much more vulnerable to overwatering, but they usually don’t die from root rot; instead, they will die from a disease called damping off, which attacks both the roots and base of the stem, causing seedlings to flop over and die.
4. Your Transplanted Pepper Plants Aren’t Hardened Off or Are Going Through Transplant Shock
If you’ve recently transplanted your chilli plants or taken them outdoors after starting them indoors, it’s not unusual for them to start wilting or look sick.
Any time you transplant a chilli, the plant goes through an adjustment period as it gets settled in its new location. This is more likely to happen when it has to adapt to very different conditions or if the roots are damaged during transplanting.
While some level of transplant shock is unavoidable, you can minimize it by doing the following:
- be careful not to damage the roots too much when transplanting
- after transplanting, water in the plant well so the wet soil can settle around the roots
- avoid any heavy fertilizing which can stress the chilli plant even more
- if you started your pepper plant indoors, harden it off first before transplanting
The last point is important because pepper plants started indoors have only ever been exposed to the gentle conditions of your home, always within a stable temperature range, little to no wind, and with some relatively weak lights (compared to the sun).
When you take pepper plants outside for the first time, the sun could be strong enough to cause damage to the leaves, and they could wilt or start to flop over from the wind. If you take them outside and transplant them, it can seriously stress out and weaken your pepper plants. It’s always recommended to harden off your chilli plants (and all vegetables) when you take them outside.
Hardening off means gradually exposing plants to the conditions outside. Leave them out for a few hours a day in the morning or late afternoon when the sun isn’t too strong, or all day if it’s cloudy. Each day, leave them out for an extra hour or two before bringing them back inside. Over time, the pepper plants will get sturdier stems and the leaves will adapt to the bright sun.
I usually harden off my chilli peppers (and tomatoes) over the course of 5 to 7 days, but some people do it longer, up to 10 or even 14 days. Then you can transplant as you normally would.
5. Your Chilli Plants Are Suffering from Fertilizer Burn
Overfertilization is often fatal for chilli plants. Whether you’re dealing with acute nitrogen toxicity or salt buildup over time, too much fertilizer kills (“burns”) roots which eventually kill off the entire plant.
If your pepper plants are wilting due to fertilizer burn, you can water heavily to wash away as much of the nitrogen or salt buildup as possible, but it’s often too late by that point. However, there is a chance that if any roots are still alive, the plant may be able to recover. This approach tends to work better for chilli plants in containers since you can continue flushing the soil with water multiple times and let it drain out the bottom of the containers.
I would also recommend in addition to flushing the soil with water that you prune back some of the branches so the roots have less to support as they recover.
6. Disease or Pests Are Attacking Your Chilli Plants
Various diseases or pests can cause your chilli plants to wilt, although in most cases it will be obvious to the home gardener.
Severe aphid damage can cause sap to be drained out of pepper plants, causing wilting. Even moderate aphid infestations can also worsen wilting during hot and dry conditions. Fortunately, aphids are relatively easy to get rid of. Aphids can often be washed away with a hose, and for more severe infestations you can use insecticidal soap or neem oil spray for organic pest control.
Regarding diseases, aside from the easily preventable root rot, two diseases that infect pepper plants are fusarium and verticillium wilt. Both are fungal diseases and are likely the problem if you’ve ruled out all the above (water, temperature, root damage, transplant shock, pests etc. are all accounted for). One sign of fungal wilt in pepper plants is a yellowing and wilting of leaves that also curl inward while wilting, especially if this occurs on the lower leaves and gradually up the plant.
Treatments for fusarium and verticillium wilt include using fungicidal sprays, but the recommended course of action is to use crop rotation and avoid planting peppers in that same spot for at least 3 years. If growing in containers, discard the potting mix at the end of the season and wash the container with a bleach solution (9 parts water to 1 part bleach), allowing at least 10 minutes of contact before rinsing it.