Decoding NPK

Our little jalapeno pepper plants have decided to turn their leaves yellow.  Meanwhile, our sweet pepper plants are not content to sit by and let the jalapenos have all the fun, so they have begun turning their leaves purple.  Ugh!

Jalapenos

Diagnosing the ills of these various peppers has been difficult.  It could be so many things!  At first we thought that the yellowing leaves might be the result of over-watering, so we watered less. That yielded no significant improvement.

 Then we thought that maybe we were under-watering, so we watered more by setting up a tray under the peppers with water in it so they could absorb what they need from the bottom.

 It could also be that we have been watering the plants with water from our inside tap (this water has much of its iron and sulfur removed by a filter) instead of with water directly from our well. We have changed that and are now watering with room temperature well water.

We also added a touch of quick-release fertilizer to try to give the plants a boost in case it is a nitrogen deficiency. Finally, we sprayed the leaves with a dilute epsom salt (magnesium sulfate) solution in case it is a sulfur deficiency.  Now we wait and hope things improve.

Sweet orange peppers

The purple leaves on the sweet peppers could be a phosphate deficiency.  It could also be the plants getting too cold (unlikely) or simply the plants adjusting to sunlight. We added a tiny bit of fertilizer to the soil but these plants are very small so we will likely leave it at that and wait to see how their second set of leaves look before taking further action.

In the course of all this problem solving, I have learned a lot about fertilizer.  It is always humbling to realize how much you don't know about something you assumed was pretty simple (kind of like beekeeping and sourdough bread making).  Here are some things I have picked up about fertilizer:

1) The numbers on the fertilizer correspond to the amounts of Nitrogen: Phosphorous: Potassium.  I spoke (extensively) to the shopkeeper at Richie's Feed and Seed today and she suggested that an easy way to remember what these minerals do is to think Greens: Roots: Stress.  So, one would surmise that a grass fertilizer would have a very high nitrogen content (20:0:0, for example), while a sprouting fertilizer might have a higher phosphorous content to encourage root growth in seedlings.  During my inquiries in a few garden centers today, I was directed to two fertilizers geared to plant starting.  Frustratingly, they had very different compositions (10:5:10 vs 10:52:10).  I do not think this is a typo.  It makes things very confusing.

The ratios in this one make more intuitive sense to me.

This one is made by the Jiffy seed company.

2) Fertilizers can also contain micro-nutrients such as boron, copper, iron, manganese, molybdenum, zinc, magnesium, or sulfur.  I expect that one needs to be careful with these as some plants like sulfur (like peppers, for example), while it can be detrimental to others.

3) There is both slow-release and fast-release fertilizer.  Slow-release is intended be used in the fall before putting the garden to bed or in the spring before planting.  Conversely, it is suggested to use fast-release fertilizer every 2-3 weeks throughout the growing season to replace nutrients in the soil as they are used up by the growing vegetables.  After discovering that our plain white bag of generic 5-20-20 fertilizer in the garage was devoid of any additional information, I wondered how you figure out whether a fertilizer is slow or fast release.  The Richie's lady explained that the ferilizer bag should say and if it does not than you should assume that it is fast-release.

My goodness, what a load of fertilizer information for one day.  At least my knowledge about fertilizer is growing (haha) even if my pepper plants are currently struggling.