Correction: I meant to say that overwatering *wouldn't* explain the high P and K.

I don't wander, I wonder:)

I live in S. California...not really windy where I live. My cabbage, squashes (they are in containers but will be transplanted), green beans (pretty much dead at this point), peppers and tomatoes are in full sun. The rest are in slightly less sun. I don't think it's a sun issue because it's happening to all container plants but are receiving a variety of sun exposure.

As far as how often I water, it's usually twice a week. I was clueless, so I bought myself one of those handy moisture meters to only water when they need it. Yes, the little ones need to be watered a lot more often. I think I have my watering schedule down with the help of my new toy. I'm more worried about the amount of water the receive every time they are watered.

I thought about how much water it takes for it to soak through and come out the bottom. I can do that with my little ones, but most are in huge pots on top of lawn-- can't see when they drain out and are too heavy to move to concrete so I can see. Maybe I can get some help to move those.

The pots have a lot of drainage holes and I have dug to the bottom of the pot to see if it's soggy at all. It isn't. I know I still can't rule it out completely, but it doesn't seem to be the problem.

The pot mix wasn't a starter recipe. However, the plants just not liking the potting mix for one reason or another makes sense. It's one thing that all of my container plants have in common, but why the super low N and super high PK? It just doesn't make sense.

And my mango that needs the "deep watering" is in the ground.

Thanks for your feedback! :)

First, I wouldn't put any faith in the result of a home test kit for nutrient analysis. They are notoriously inaccurate. N is an extremely mobile element and not possible to test for correctly with a home kit. Even many professional soil testing labs don't test for N unless asked specifically as it takes special testing. And most soil test results will recommend adding N, simply because it is so mobile and transitory in the soil and nearly always needs supplementation.

The higher P & K can be attributed to your potting mix. Compost is a strong source of these. And worm castings are extremely nutrient rich. I don't think your issues are with soil test or what the nutriment levels may or may not be. Your fertilizing and the richness of the mix are making sure the plants get what they need nutrient-wise.

Your problem is the soil. It's too finely textured and too dense. And it's retaining too much moisture. The fine texture and density are just as detrimental as the moisture retention and all three in combo are problematic - lack of aeration, compaction and excessive moisture. This is what's causing the yellowing.

Compost is not a great addition to a potting mix. It is what promotes the moisture retention and it contributes to compaction and lack of aeration as it continues to decompose. You want a mix that is more textural and durable (not prone to additional decomposition). These are typically going to be mixes that are bark-based. The following is a homemade mix that is very popular. You can find more details on this and other excellent potting mixes on the Container Gardening form.
5-1-5 Mix

5 parts pine bark fines, dust - 3/8 (size is important

1 part sphagnum peat (not reed or sedge peat please) coir can be substituted for the peat

1-2 parts perlite (coarse, if you can get it)

garden lime (or gypsum in some cases)

controlled release fertilizer (if preferred)

Thank you GardenGal! That all makes sense to me.

I'm also thinking about your soil. You might simply try a test of repotting a plant in a box store potting mix or something of that sort.

Mostly, keep it simple and don't overthink things. People go on and on about what fertilizers they use, but really, it's mainly the same stuff, just different variations; maybe "trace minerals" added, etc...

Start with your soil. If you're STILL having less than nice results, then look at your fertilization regiment.

Think of what plants need in nature - soil, sun and water! First things first - SOIL

Sorry, I overlooked the question about the mango. Mango and avocado - both fruit trees. As they are getting aquatinted with their new home, it's good to water them twice a week. How long has the mango been there? How big is it? When planting, did you make sure the graft line is above the soil? Don't be afraid to sprinkle a little general fertilizer (13-13-13) around the base and keep the grass from growing up to it. I'm in zone 9a, but am usually wet here, so I don't water "deeply." That's a relative term anyways. Just give them enough water to make you feel good. Don't drench the soil. You can also post your question about the mango on the fruit forum. There's a lot of really knowledgable people on that one! Good luck!

I planted the tree about a month ago. It's about 5-6 feet tall. I did plant it so the graft line is above the soil. I put a little mound of soil at the base, but the graft is above that. I also mulched it. I just don't know if I should spend 20 seconds watering the thing or 10 minutes. The "deeply" thing really threw me off. Thanks again!

Squash grow really rapidly! When my squash were the size pictured, they also turned yellow, and I had to transplant them. The roots were already filling the container and with a dark container this can allow heat to scorch those roots pressed up against the container. Sometimes yellow just means "I need some space!"