When to Bring Your Plant indoors
When the night temperatures dip into the 40s, it's time to start the process of overwintering.
Have your final pepper harvest.
Prune Back the Plant
Remove all the leaves, and trim your plant back significantly with sterilized pruners. It will be only a stalk with a few short branches sticking out.
Your plant will be in hibernation throughout the winter, and the leaves can serve as food for pests.
That said, we have had success keeping the leaves on if the pepper plant is overwintering in a sunny location of the house, so feel free to experiment. This is mainly true for smaller plants. We won't stop you from bringing a 3ft tall plant inside, but that size we'd recommend pruning.
Inspect your Plant for Signs of Insects
The most likely insects you'll see are aphids or whiteflies.
If there is ANY indication insects are present, do not bring your plant inside! If you have other house plants or vegetable starts, insects will spread rapidly indoors with no natural predators.
If you see aphids later on, a treatment with insecticidal soap is a good strategy. If you see whiteflies, our advice is to discard the plant. It's not worth it the risk to your other plants! If you only have one plant inside, then there is low risk to trying out methods of eradication.
Repot your Pepper Plant
This is another strategy to reduce the likelyhood of insects, since eggs or the pests themselves can be in the soil.
Prepare a second container with new soil.
Remove the pepepr plant to overwinter and clean the soil off the roots. Untangle the roots if applicable. Get the roots as clean as possible by removing all soil.
If the container you're planting into is smaller than the container you're planting from, trim the roots of the overwintering plant with sterilized scissors.
Water the pepper plant in the new container lightly. It will be out of the sun and using very little water over the winter, so do not fully saturate the soil.
The same process applies for pepper plants in your garden - it's just a little bit more digging.
Choose a location that can be maintained above 50°.
In frost-prone climates, this means an unheated garage is unlikely to be warm enough.
A lot of sunlight access isn't essential since the plant will be dormant. If a closet is your best option, give the plant some light for 8 hrs a day. It does not have to be a full-spectrum grow light for this application.
If you have the space, it's best to have overwintering pepper plants in a separate location from other house plants to reduce the chance of insects effecting those plants.
Throughout the Winter
Your pepper plant will most likely grow new leaves after pruning since pruning stimulates growth. You can pluck or let them remain since they will be small, and the insect risk should be reduced by the time they appear.
Water very lightly - it will most likely be about 1 time per month. Just like over-watering is the biggest problem for growing plants during the season, it's also the most likely pitfall for overwintering plants.
Spring is Here!
When daytime temps start to be in the 60s, you can start hardening off your pepper plant.
Very lightly fertilize your pepper plant at 1/4 dilution.
Bring your pepper plant outside during the day, starting with just a few hours at a time in a spot that is not in direct sunlight. Too much sun too soon will stress the plant.
Don't forget to bring your plant in at night!
Continue hardening off, extending the time your plant is outside until night temperatures are reliably above 55°.
When your plant is fully established outside, begin a regular fertilizing regimen.
We happen to have a sunny mudroom with no other plants, so most of the time we just bring the plants we want to save that are in manageable containers inside with minimal pruning or cleaning.
We also have access to many other plants next year if things don't work out, so the risk is a bit lower!
Spending the time to carefully repot will increase your chances of success, but if you understand the risks and want to save some time in the fall, it seems only fair to provide a real-world anecdote.