Growing Peppers In Cold Climates & The Subarctic | Frosty Garden

Growing Peppers In Cold Climates & The Subarctic

One of the most popular topics on the Frosty Garden blog is the subject of growing outdoor tomatoes in the far north.  We also grow a fair number of peppers outdoors in our cold climate, so it’s time for some of our top tips for growing peppers in the subarctic!

We’ve found great success with growing outdoor peppers in the interior of Alaska.  They often do better most years than our tomatoes.  While we don’t have bushy six foot tall pepper plants, we always get a decent harvest of peppers.

1.  Stick With Basic, Early Varieties

Unlike with tomatoes, there are very few varieties that have been bred for cold climate growing.  With peppers, there are just some types that do better than others in cold climates.

In general, you need to do a bit of research on the varieties you might want to grow.  For best results, seek pepper varieties that reach maturity in the 50 to 75 day range.

If you have a greenhouse, your season is longer and you could grow peppers with slightly longer maturation times.  Many varieties of peppers, including a lot of the super hots, require well over a hundred days to grow and then mature.  These might be out of reach unless you’re prepared with some of the ripening techniques discussed here.

It’s important to keep in mind that with peppers, the estimated day to maturity is an edible, but green pepper.  The green pepper may not be what you have in mind for a “ripe” pepper.  It can take days to weeks longer for a pepper to change colors (fully ripen), and it usually requires a good streak of warm weather.

For pure outdoor growing, our experience has shown that some of the most basic pepper varieties do the best here in Alaska.  You’ll notice that most of them are considered “ripe” when they are still green.  Examples of these include:

  • Jalapeno
  • Serrano
  • Anaheim
  • Banana wax peppers
  • Thai peppers

Some hots and super hots will also take to our climate, such as the habenero and bhut jolokia (ghost peppers).  It’s not uncommon to only get a handful of truly ripe peppers from these plants, however.  Check out the UAF Extension Service recommended varieties for a decent initial list of peppers that grow well in the sub-arctic.

We’ve had great success with early varieties of jalapenos.  These are usually our most prolific plants, sometimes providing a dozen or more peppers from each plant.  These can even continue to put on peppers if you harvest them mid-summer.

With peppers that require some maturity to be right, it can often take some finessing to get them to full maturity.  We will discuss some of the techniques we use further in this post.  These techniques allow us to grow any kind of pepper to full maturity.

2.  Forget About Growing Bell Peppers

Unless you have a greenhouse, you most likely won’t be growing bell peppers very successfully in the sub-arctic.  We have tried different varieties of bell peppers, even the most early varieties, and the poor yields just make them not worth growing.

Our experiments have largely been with the Ace hybrid variety, a super early sweet bell pepper, known for cool climate performance.  Unfortunately, even with these, we’ve only been able to get 1-2 fruit that will grow to full maturity.  At that point, you’re probably paying $5+ per pepper and it’s only about two to three inches in diameter.  That’s just too marginal for us to put resources into growing them.

We will probably continue to experiment with bell peppers, but they have been tough to crack.  It may be that these just simply require the use of a greenhouse and growing them outdoors is beyond reach.

If you are able to test or report on any varieties of bell peppers that do well in cold climates, be sure to leave a comment.

3.  Get An Early Start On Your Peppers

In most northern climates, there is not enough growing season to get a pepper plant to full maturity.  If you want to raise your own peppers in the north, you will need to start them inside or purchase pepper starts from a nursery.

For outdoor peppers, plant your seeds 7-8 weeks before last frost.  The earlier of those dates will ensure a larger transplant and better pepper production.  Your pepper plants will also be larger, so make sure your indoor growing space can accommodate this.

If you will be growing in a greenhouse, you can start your peppers 8-10 weeks before last frost.  This will allow you to transition your peppers to your greenhouse after frost danger has passed.

Peppers need relatively warm soil temperatures to germinate, typically around 70 degrees.  If you are growing with ambient light near a window, or a place such as a garage, you may see troubles with germination.  You can use alternative germination techniques, such as germinating the seeds in a paper towel, to help get an initial seed to sprout.

If you are buying pepper plants, look for fairly mature plants.  Don’t settle for a pepper plant that is 3 inches tall, try to find peppers that are at least 8-12 inches tall.  You want the summer’s warmth to be spent on producing fruit, not getting the pepper to basic fruiting maturity.

4.  Transplant Peppers 2+ Weeks After Last Frost

An unexpected late frost or cold snap can wipe out a pepper plant.  This is a very real risk in our northern cold climate.

Peppers are much more sensitive to cooler temperatures than tomatoes are.  Putting peppers outside when the temperatures are still in the 30’s to 40’s can seriously stunt their growth.  This can affect the pepper’s growth over the whole season.

We’ve found it a best practice to put peppers outside when the evening temperatures are virtually guaranteed to be over 50 degrees.  We sometimes push high 40’s, but try to avoid it if possible.  This is usually about two weeks after our last frost date, or around June 15th within Interior Alaska.

You can use this time for hardening off your peppers to both sunlight and our cooler northern temperatures.  As the evening temperatures approach 50+ degrees, you can leave them outside if they’ve been sufficiently hardened off.  Keep bringing them inside and outside, as needed, until after it’s very clear the danger of cold temperatures has passed.

5.  Grow Peppers In Containers

Growing your peppers in containers allows you flexibility throughout the plant’s life cycle.

Early and late season can be very dicey in Alaska and many northern locations.  Remember that an average last/first frosts are just that, an average.  You can still see frost earlier – or later.  Keeping your peppers in containers allows you to guard against virtually anything, even a June snow!  Juneuary is what we like to call it.

Peppers tend to drink a lot of water.  While they are more drought tolerant than tomatoes, growing peppers in containers can be challenging.  You will need to keep on top of watering them, especially later in the season.  An irrigation system or sub-irrigated containers may be beneficial to save you time.

For us, we’ve also found it highly beneficial to bring our peppers indoors for final ripening.  If our peppers were planted in the ground, that wouldn’t be easy.  With our peppers in containers, we can bring some of them indoors in late season and fully ripen the peppers within a few days.  We use our DIY COB lighting system and it works great for this purpose.

6.  Use 5+ Inch Pots For Pre-Transplant Peppers

For most commercial growers, 4 inch pots for pepper transplant are the norm.  We use 5.5 inch pots in the sub-arctic and there’s a good reason to consider this.

As with the above recommendation, in the north, we have to gauge when the weather conditions are suitable for peppers.  If you transplant your seedlings into 5.5 inch pots, you can get well into June before you need to transplant.  Your pepper starts will also appreciate the room for additional roots and your start will be larger.

If your indoor garden is cramped for space, 5.5 inch pots may not be the best idea in the early season.  Peppers are not super sensitive to transplanting, so it’s fine to consider a smaller pot (we recommend 3.5 inch) as an interim transplant step.  Once most of your plants are outside, you can up-pot your peppers to these larger pots.  This allows us to use our indoor growing space for further pepper plant maturity once many of the other veggies and flowers are outside.

7.  Assist Your Pepper Pollination

Alaska and many northern climates tend to have less numbers of naturally pollinating bees and flies.  It’s very helpful to assist your peppers in the pollination process as it will lead to increased yields.

Just like with tomatoes, peppers are self-pollinating.  This means that the flower can pollinate itself.  You can virtually guarantee pollination if you tickle/shake the flowers as they open.  We like to repeat this once every day or two as long as the pepper is putting out flowers.  Some people use electric toothbrushes or other gizmos, but we’ve found success using our fingers.

8.  Aggressively Feed Your Peppers

As with all vegetables growth under the midnight sun, peppers will eat a lot more when exposed to 18+ hours a day of sunlight.  Often, even a rich compost is not enough food for them to last the entire season.  It is a good idea to supplement your peppers with regular feedings throughout the summer.

Once your peppers have a couple sets of leaves, it’s time to fertilize them.  Early in the pepper’s life, you want to use a high nitrogen based fertilizer to encourage the plant’s growth.  This will help the plant to grow larger, which in turn results in higher yields.  When plants are small, a good recommendation is generally 1/4 the dose of your preferred fertilizer. 

Once the plant starts to put out flowers or upon planting outdoors, transition the plant to a fertilizer higher in phosphorus and potassium.  (i.e. higher P & K values or the last two sets of numbers on a fertilizer’s rating)  Tomato fertilizers are a good choice as peppers share similar nutritional needs.

Follow your fertilizer directions, but we are often fertilizing every 7-10 days to fuel more rapid growth.  In our sub-irrigated containers, we tend to treat them like hydroponics and provide a constant feed rate of fertilized water.

9.  Have A Plan For Pepper Maturity

When you look at seed packets for peppers, the maturity date is defined as an edible green pepper.  That may not match your expectation of a ripe pepper.  It can take quite a few days (or even weeks) for a pepper to fully ripen.  This is especially important for super-hot and colorful varieties that need to be ripe for best eating.

Peppers ripen best in warmer temperatures.  In interior Alaska, August can often be a rainy, cooler month.  This can make it challenging to grow peppers as your prime time for ripening are less than ideal for it.

If you can, consider using an indoor growing space to ripen your peppers.  If you can do this, you can grow almost any variety of pepper and get a rather decent yield of ripe peppers.  This technique also allows you to grow super-hot peppers that often need much more time to fully ripen.  This is our biggest reason for using higher end LED lighting in our indoor garden, it allows us to finish growth cycles indoors.

With this technique, you could theoretically grow any kind of pepper out there.  Think of summer as a free, three month grow room.  There are some ridiculously long growing super hots, like in the 180+ day range.  We’d recommend starting out with basic peppers described above, but any pepper lover will want to experiment with varieties eventually and this is the most reliable technique for the sub-arctic.

Outdoor grown peppers don’t tend to get humongous in Alaska like they do in warmer climates.  We usually see about 2-4 feet tall, and most on the shorter side.  This is often a manageable height for moving them indoors if you choose to do so.

10.  Keep An Eye Out For Bugs

The lack of garden pests in Alaska is probably one of the best reasons we like to grow here.  We aren’t fighting beetles, caterpillars and slugs.

But, some years we can get infestations of aphids.  They are horrible.  These dastardly bugs absolutely love pepper plants and will destroy them if allowed to.

Periodically, you should be checking your pepper plants for aphids or other pests.  If your plants are having a hard time all of a sudden, this is one of the first things you should check for.

You will find aphids crawling on the backs of the leaves and plant stems.  They are tiny, so you have to look carefully.  If you see symptoms of plant health that can’t be attributed to watering or feeding issues, look for aphids.

If you get an infestation, it’s a good idea to resolve it as soon as possible and across your entire garden.  A popular method of aphid control is neem oil.  Most brands of this are organic and it’s generally safe to apply.  There are oil based versions and sprays and for our scale of gardening, a spray bottle is preferred.  Apply the neem oil to the backs of leaves and the stems of the pepper plant.

If neem oil doesn’t cure your bug ills, you may need to escalate to an insecticide.  These are more harsh and can be harmful to humans, so be careful in their application.  Be certain that an application of insecticide is “food safe” – it’s not safe, but it should wash off with ease.  There are similar products that aren’t food safe, these are intended for non-edible plants.  As with neem oil, apply the insecticide to the backs of leaves and stems of the plant.

Regardless of what you use, it’s a good idea to thoroughly wash your vegetables before you eat them.  This is recommended even if you use neem oil, which is generally regarded as safe.  If you use insecticides, always recommended to thoroughly wash your veggies before eating.

11.  Grow More, Smaller Plants

The truth about peppers in northern climates is they will end up being smaller than peppers grown at lower latitudes.  If grown outdoors, you won’t have hundreds of peppers falling off any pepper plant grown in Alaska.  If peppers are your jam, you would do well to heed this advice.

You can still get an epic pepper harvest, but you may need to think in terms of plant quantity over plant quality.  It might be better for you to grow more pepper plants to get the harvest you want.  They tend to be fairly compact and easy to deal with overall, so more of them isn’t always a bad thing.

One thing we’ve considered with our pepper gardens is to focus primarily on one or two varieties.  This allows for greater production of a single type of pepper, which can help when you go to use them.  We also struggle with that decision every year because it’s so tempting to have many varieties!

In Conclusion

Pepper harvests are always fun.  Peppers are a great addition for the preserver and add a great dimension to food.

We use them not just for fresh eating, but also preserve the majority of our harvests.  We use a fair amount of our peppers in hot sauces, but also like to dry some into pepper flakes or powder.  Peppers also take well to being frozen and you can do so whole, halved, sliced or diced.  

We hope that you enjoyed our tips for growing peppers in the sub-arctic and other cold climates.  If you have any tips yourself, feel free to leave a comment.

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