Question
We have planted tomatoes and bell peppers in plastic containers for the past 3 years.  We tend to use the same dirt/soil but add a little each year to top off the pots.  Last year we had few tomatoes with a black bottom and this year we already have green peppers with black spots on the bottom.  We live in Minnesota.

We usually water them everyday because they take in a lot of sun and dry up quickly on the hot patio.

Is this a disease in the soil?  Any advice would be appreciated.

Thanks,
Megan

Answer
Megan, when peppers or tomatoes rot prematurely on the bottom of the fruit, it is usually an indication of blossom-end rot. This condition is caused by inconsistent watering and/or a lack of calcium in the soil.

When plants are watered too shallow, the roots reach for the surface causing stress and poor nutrient intake.  By the same token, when plants are given too much water, the roots are deprived of oxygen and cannot absorb specific nutrients that are not as concentrated as others.  Calcium is one of these nutrients.

Most soils in the US are very low in calcium.  To counter this problem, you can add crushed eggshells to the soil or you can spray the plants with a solution of 1 tbs. of epsom salts per gallon of water. Although epsom salts are comprised primarily of magnesium, it has been proven that the plants will draw more calcium and other vital nutrients more efficiently when sprayed with epsom salts. I add one or two tablespoons into each planting hole in the spring, and I seldom experience problems with blossom-end rot on either my tomatoes or peppers.

Finally, if you're not getting at least 1.5" of rain per week, make sure you water the soil deeply once or twice per week.  This will force the roots to grow deeper where lesser concentrated nutrients are more readily available. You should also mulch the plants heavily with dried grass clippings or straw to help retain moisture.

I hope this information helps.  Good luck, and please write again if I can ever be of assistance.

Regards,

Mike