If you are like most gardeners, you want to get your pepper plants started as early as possible. You also want to keep growing them for as long as you can.
However, the weather does not always cooperate, and late spring frosts or early fall frosts can kill your plants.
So, what is the lowest temperature pepper plants can tolerate? A temperature of 32 degrees Fahrenheit or below will result in frost, which will kill your pepper plants. Any temperature below 55 degrees will slow down the growth of mature pepper plants, and will stunt seedlings. Peppers grown from seed should not be exposed to soil colder than 75 degrees Fahrenheit.
Luckily, there are plenty of ways to protect your pepper plants from cooler temperatures. Taking a few of these measures at the beginning and end of the season can extend your season by a few weeks.
In this article, we’ll take a look at some of the ways to protect your peppers from cold – given in approximately chronological order.
Let’s get started.
Choose The Right Pepper Varieties
To protect pepper plants from cold, the first step is to choose the right varieties for your climate. This is before you can even think about when to germinate seeds, transplant seedlings, or choose a location in your garden.
Based on your location, the USDA plant hardiness zone map will tell you what zone you live in.
In general, the lower the zone number, the harder it will be to grow peppers, due to a short growing season. If you live in a colder region, consider pepper plants that are:
We’ll start with cold tolerant pepper plants.
Cold Tolerant Pepper Plants
Peppers are a warm-weather crop, which means that they don’t do as well in cool climates. However, there are some cold-tolerant varieties that are adapted to cool weather, such as:
- Ace Pepper – this bell pepper does well in cool climates where other varieties might suffer. Another benefit is that they mature quickly, taking only 50 days from transplant to mature green pepper (70 days to a mature red pepper). Learn more about the Ace Pepper from Johnny’s Selected Seeds.
- Bulgarian Carrot Chile Pepper – this open pollinated heirloom chile pepper is 3 inches long, thin, and orange, just like its namesake carrot. It is adapted to cool northern climates. It takes 75 days to grow from seed to mature peppers, which are very hot. Learn more about the Bulgarian Carrot Chile Pepper from Sandia Seed Company.
- Intruder Pepper – this bell pepper is adapted to the Northeastern U.S. with its cooler climate. It also has good disease resistance. It produces mature green peppers in 62 days (82 days for mature red peppers). Learn more about the Intruder Pepper from Johnny’s Selected Seeds.
- Manzano Pepper – this open-pollinated heirloom chile pepper from the Andes in South America is also called “Apple Chili” or “Orange Rocoto”. This unique pepper has black seeds and hairy leaves, and it grows well in cool weather and shade. They can live and produce fruit for 15 years if they survive winter! It takes 100 days to grow from seed to mature peppers, which are very hot. Learn more about the Manzano Pepper from Sandia Seed Company.
- Yankee Bell Pepper – this open-pollinated bell pepper is adapted for northern growers in cold climates. It produces mature green peppers in 60 days (80 days for mature red peppers). Learn more about the Yankee Bell Pepper from Johnny’s Selected Seeds.
Although the varieties listed above are cold-tolerant, they are not invincible. Frost is still deadly for these pepper plants.
If there is not much time between the spring and fall frosts in your climate, consider fast-maturing pepper plants.
Fast Maturing Pepper Plants
Even if you have a short summer in your region, you can still get a good pepper harvest, provided that you grow them fast enough. There are several fast-maturing pepper varieties to choose from, such as:
- Bell Sweet Chocolate Pepper – this heirloom open-pollinated bell pepper is chocolate-colored and sweet. At 3 to 4 inches long, the fruit matures fast, taking only 57 days from seed to mature pepper harvest. Learn more about the Bell Sweet Chocolate Pepper from Sandia Seed Company.
- Early Jalapeno Pepper – this heirloom open-pollinated jalapeno pepper is very hot. The fruit is 3 inches long and matures fast, taking only 65 days from seed to mature peppers. Learn more about the Early Jalapeno Pepper from Sandia Seed Company.
- Fushimi Sweet Pepper – this heirloom open-pollinated pepper variety has long, thin fruit with crispy skin. The peppers are not hot, and they take only 80 days to grow from seed to mature fruit. Learn more about Fushimi Sweet Pepper from Sandia Seed Company.
- Shishito Japanese Sweet Pepper – this heirloom open-pollinated pepper variety has fruit that is 3 to 4 inches long. The fruit is not hot, and it takes only 60 days to grow from seed to mature peppers. Learn more about the Shishito Japanese Sweet Pepper from Sandia Seed Company.
- Sweet Banana Pepper – this heirloom open-pollinated pepper produces yellow peppers shaped like bananas. The fruit has low heat and matures in only 75 days from seed to harvest. Learn more about the Sweet Banana Pepper from Sandia Seed Company.
- Yellow Jalapeno Pepper – this heirloom open-pollinated pepper produces very spicy yellow peppers that are 3 inches long. This variety only takes 65 days to mature from seed to harvest. Learn more about the Yellow Jalapeno Pepper from Sandia Seed Company.
As with any peppers, you will still need to protect the varieties listed above from frost. However, their fast growth and short time to maturity should help you to avoid the cold weather.
Decide On A Pepper Planting Schedule
At this point, you have decided on the pepper varieties that you want to grow. Now, it’s time to take a look at the time to maturity.
The seed websites should have this information, or you can find it on the seed packets. For example, the Yellow Jalapeno Pepper (mentioned above under fast-maturing varieties) has a time to maturity of 65 days.
You also want to find the first chance of frost in your area. The Farmer’s Almanac has a tool that you can use to find the frost dates for your region.
For example, the first chance of frost in my area is October 1st. So, I will want to harvest my peppers by September 30.
Then, I work 65 days backwards from there: 30 days in September, 31 days in August, and 4 days at the end of July.
I would also need to leave some time for a harvest window – perhaps 2 weeks (14 days). This would put us back to a last planting date of June 20.
That means I would want to plant my pepper seeds by June 20 at the absolute latest for a fall harvest. You can learn more about how to speed up pepper seed germination in my article here.
Of course, my peppers would not do very well once the nighttime temperatures start to get into the 40s Fahrenheit.
Planting earlier than this would be much better for my harvest. Hopefully, this example illustrates the point about how to plan ahead for your garden’s planting schedule.
Start Pepper Seeds Indoors
For pepper seeds, the soil temperature needs to be at least 60 degrees Fahrenheit (16 degrees Celsius) and at most 95 degrees Fahrenheit (35 degrees Celsius) to achieve germination.
According to the University of California, the ideal soil temperature range for pepper seed germination is 65 to 75 degrees Fahrenheit (18 to 24 degrees Celsius). At those temperatures, the seeds should germinate in 7 to 14 days.
However, your soil may not get that warm until later in the season. You have two choices to bypass this limit:
- buy established pepper plants from a garden center
- start your own pepper seeds indoors
The question is, when should you plant the seeds? It will depend on the variety of pepper plant you choose.
A good guideline is to plant the pepper seeds 4 weeks before the last chance of frost. Then, transplant the seedlings outside 4 weeks after the last chance of frost.
This means that the plants will be indoors for 8 weeks total.
For example, let’s say the last frost is May 8, and I want to plant the pepper seeds indoors 4 weeks (4×7 = 28 days) before that date.
Working backwards, we find: 8 days in May and 20 days at the end of April, for 28 days total. So, I should plant the seeds indoors on April 10 (30 days in April minus 20 days at the end of the month gives us the 10th).
Keep in mind that the soil temperature should ideally be kept at 65 to 75 degrees Fahrenheit (18 to 24 degrees Celsius) to speed up germination of your pepper seeds.
Let’s say I decide to transplant the seedlings outside 4 weeks (4*7 = 28 days) after the last chance of frost. Working forwards, we have 23 more days in May (31 – 8 – 23), plus 5 days at the beginning of June, giving us 28 days total.
This means that I will transplant the pepper seedlings outdoors on June 5. Of course, if there is unseasonable cold in the weather forecast, I will wait a few days until conditions improve.
One more thing to remember: you can use two different types of light to grow your pepper plants:
- grow lights (artificial lighting, such as LEDs)
- sunlight (from a window or skylight)
If you do place pepper seedlings close to a window, be sure that they don’t get caught in a cold draft. Otherwise, your season for growing peppers could be over before it even begins!
If you have trouble getting your pepper seeds to sprout, check out my article on how to get your pepper seeds to germinate.
Watch Weather Forecasts Before Transplanting Pepper Plants Outside
Even if you are careful about choosing pepper varieties and timing your planting, nature may have other plans. The dates for first and last chance of frost are usually reliable.
However, they are based on probability, which is no guarantee. Once in a while, you will see a year with strange weather patterns.
In this case, you should watch the short-range and long-range weather forecasts. When it gets close to the time that you transplant seedlings outdoors, make a decision.
If you see a forecast for a stretch of unseasonably cold weather or an extremely cold night, keep the pepper seedlings indoors for a little longer.
Apply Cold Treatment To Pepper Plants
You also have the option of applying cold treatment to your pepper plants. This will toughen them up and prepare them for cold weather.
The idea is to expose them to weather a little colder than they would like (not freezing temperatures!), before they really get going.
Ideally, you would put the pepper plants in a location with plenty of light and a temperature in the low to mid 50’s (50 to 55 degrees Fahrenheit) for four weeks. This cold treatment forces the pepper plants to put more energy into developing roots, stems, and branches.
In the short term, cold treatment slows down the growth of the pepper plant. In the long term, cold treatment will give you more flowers and peppers.
Cold treatment makes a pepper plant more resistant to cold. However, if you have a short growing season, you might not have time for cold treatment.
Being more resistant to cold will not help your pepper plants in a frost or freeze. If you have a longer growing season and want to increase your pepper yield, cold treatment is an experiment you can try.
Select The Best Locations For Pepper Plants
If you choose to grow some of the cold-tolerant pepper varieties mentioned earlier, you might be able to plant them in cooler, shady spots in your garden. For example, the Manzano pepper grows well in cool weather and shade.
However, if you are planting standard varieties, choose a spot in your garden that gets more sun. Most pepper plants need full sun (8 or more hours of direct sunlight per day) to grow their best.
As an added benefit, more sun exposure will make the soil warmer during the day, and that heat will last longer at night.
If there is an area of your garden that is protected from wind, that can also help to prevent damage. If you want to find out ways to provide your own shelter, check out my article on how to protect plants from wind and storms.
Protect Established Pepper Plants From Cold
There are several ways to protect established pepper plants from cold, including:
- cloche (for younger, smaller pepper plants)
- cold frame (for younger, smaller pepper plants or seedlings)
- row cover (for taller, more established pepper plants)
- greenhouse (for keeping pepper plants warmer all season)
Use Cloches To Protect Young Pepper Plants From Cold
An easier, low-cost alternative to a cold frame or greenhouse is a cloche. A cloche is simply a cover meant to protect plants from cold temperatures.
Originally, a cloche was a bell-shaped glass cover to put over plants. However, without a vent, a glass cloche will trap too much heat unless you manually take it off of the plant.
You can also use a plastic cloche to trap heat. A wire cloche is often used to protect plants from rabbits or other creatures.
However, a wire cloche by itself won’t keep the plants warm. You will need to wrap a frost blanket or piece of row cover around a wire cloche to provide cold protection.
The top of a plastic cloche should have a hole to allow plants to breathe and to allow excess heat to escape. Conveniently, a cloche can also deter some pests from damaging your pepper plants.
If you want to make your own cloche, simply collect empty plastic gallon containers of milk or water. Then, cut out the bottom, and put the container over your plants.
When it gets hot, remove the cap on top of the plastic container to allow the plants to breathe.
The only downside of a cloche is that your pepper plant will eventually outgrow it. However, a cloche is a good way to keep young plants warm if you transplant early, or if an unseasonably cold spell comes through.
Use A Cold Frame To Protect Pepper Seedlings From Cold
Sometimes, you want to transplant your seedlings outside a little earlier. Other times, your spouse yells at you for having too many plants in the house.
Either way, a cold frame can help you out! A cold frame is a short wooden structure with a glass or plastic top.
It acts as a “mini greenhouse”, helping to keep plants inside warm. Many cold frames open automatically when the temperature inside gets too high, and close again when it gets low.
You can transplant your seedlings directly into the cold frame when they are mature enough, and when temperatures are warm enough. Just put a thermometer in the cold frame and monitor it every day.
You can also use a cold frame for cold treatment if you transplant earlier in the season. Just watch out for frost in the weather forecast!
Use Row Covers To Protect Taller Pepper Plants From Cold
What should you do if your pepper plants are too tall for cloches, but still need cold protection, perhaps towards the end of the season? In this case, use row covers to keep your plants warm.
One way to do this is to fashion flexible plastic rods into half-hoops, with both ends stuck into the ground. Once you have enough of these rods along the row, put a length of garden fabric over the hoops.
You can also use a tomato cage to hold up a row cover over a pepper plant to keep it warm. As an added benefit, it will provide support for the plant as it grows.
For more information, check out my article on why to use tomato cages.
In addition to providing cold protection, row covers will protect pepper plants from pests. As with a greenhouse, high temperatures can spell trouble for plants under a row cover.
If the temperature rises above 85 degrees Fahrenheit (30 degrees Celsius), then take the cover off, and replace it when temperatures cool down.
Use A Greenhouse To Protect Pepper Plants From Cold All Season Long
If you want to protect your pepper plants from cold temperatures throughout the growing season, transplanting directly into a greenhouse is a good option.
You can build one yourself, hire someone to build it for you, or purchase a pre-fabricated greenhouse.
As with a cold frame, you should put a thermometer inside your greenhouse and monitor the temperature.
If daytime temperatures are consistently 65 to 70 degrees Fahrenheit, and nighttime temperatures are consistently above 55 degrees Fahrenheit, then you can think about moving pepper plants from indoors to the greenhouse.
If you move your pepper plants to the greenhouse early, make sure to keep the door closed to keep heat trapped inside. Otherwise, you could damage or lose your pepper plants on a cold night!
On the other hand, a stretch of hot, dry weather could stress the plants. Pay attention to the weather, and open the greenhouse door or vents if necessary.
Look at the weather forecast regularly. If the forecast calls for a hot, sunny day, then leave the greenhouse door open before you leave for work.
Pinch Off Early Flowers From Pepper Plants
This technique is totally optional, just like cold treatment (mentioned earlier). However, it is similar to cold treatment in that it can toughen up your pepper plants and increase your yield.
The idea is to pinch off some early flowers from your plants. Instead of putting energy into developing fruit right away, the plant will instead use that energy to strengthen its roots, stems, and branches.
After the plant gets stronger, let it flower and produce its fruit. The result will be more and larger fruit, and a plant that is more resistant to wind and cold.
Again, this is a method that slows down your harvest in the short term, but improves your harvest in the long term. You may not have time for this in a colder climate, but together with cold treatment, it can really toughen up those pepper plants!
Now you have an idea of the temperature range that your pepper plants can tolerate before they slow down their growth or succumb to cold.
You also have plenty of ideas on how to protect your pepper plants from cold, extend the growing season, and increase your harvest.
I hope you found this article was helpful – if so, please share it with someone who can use the information.
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