Question
I've been planting some different kinds of chili for a two years now and I live in northern sweden and have up to 20 hours of sunlight during summer. I usually have them planted in a huge pot outside during summer and when there's a risk of night frost I move it inside. I've been getting a reasonable harvest but I want to get some tips for this year. What temperature range is best for Jalapeno, PiriPiri, and others in general (I've got a few bigger ones planted from unknown seeds).
Is it better to bring them up indoors until flowering or is it better to let the fruit finish indoors. Do you have any other general tips for me?

Answer
Max, peppers need several things in order to produce a good harvest with good sized fruit.  Three important factors are good soil, strong sunlight, and favorable temperatures.

When giving advice on vegetable gardening, I always stress the importance of good soil.  It is without question the primary difference between gardens that produce healthy, bumper size crops, and those that are plagued by disease and insects.

Unless you are using an organic potting soil, be sure to work the soil well by mixing in as much organic matter as possible.  This would include compost, aged manure, and other amendments such as peat and humus.  By using organic materials, you are increasing the number of microorganisms in the soil which result in increased resistance to diseases and insects while, at the same time, providing the necessary nutrients for the plants. It also improves the tilth of the soil which improves water retention and soil temperature. In short, plants thrive in composted soil.  Many communities have programs that offer compost free to local residents.  If not, you can purchase composted soil at most reputable garden centers.

For most vegetables, you also need to ensure that the PH balance of your soil is as close to neutral as possible.  A neutral soil has a PH balance of 7.0. Peppers are one of the exceptions since they like slightly acidic soil; somewhere around 6.2 - 6.5.  If you're not sure what your PH balance is, you can purchase a PH kit at most garden centers.  They are inexpensive and very accurate.  If your soil is too acidic, simply add garden lime to your soil.  If it is too alkaline, add sulfur.  One advantage to using composted soil is that PH is seldom an issue since compost is as close to neutral as possible.

Next, peppers like warm temperatures, but not necessarily too hot. Between 80F and 85F is ideal.  Over 90F and they tend to stop producing until the temperatures cool again. Under 80F and they go dormant. That is why I would suggest you bring the plants indoors at night, but be sure to move them back outside during the day to ensure they get the proper amount of sunlight; at least 8 hours per day.

Also, do not overfertilize, especially with water soluble chemicals high in nitrogen.  Nitrogen tends to promote lush foliage at the expense of sizable fruit.  Instead, you want fertilizers with a higher ratio of phosphorus and potassium.  I personally use fish emulsion once every 10 days.  Another good catalyst for peppers is epsom salts.  Most oldtime gardeners swear by the results.  Simply dissolve one tablespoon per gallon of water and apply once per month for great results.

Finally, water to a depth of 1.5" per week.  Overwatering causes more harm than good by depleting the soil of nutrients and depriving the roots of oxygen, especially when growing in pots.

I hope this information helps.  Please write again if I can ever be of assistance.

Regards,

Mike