I've ordered a 3 gallon fertilizer injector and I think I've calculated a formula to start with: 12 parts vinegar: 1 part foliage pro I'll set the fertilizer injector at 250:1 This should deliver almost 1 TB vinegar per gallon of water and 1/4 tsp of FP per gallon. From what I've read the vinegar should lower the ph by approximately 1. Drip irrigation will be watering/fertilizing almost every day. On the weekends, I will probably hand water as needed, especially to flush out the containers. I'm sure this will need some tweaking, but that's my starter plan Anyway, if anyone has advice for me on that, I'm all ears. However, my real question is whether it is safe to combine vinegar and FP. From reading other threads, it seems like people have done it with other fertilizers, but always diluted with water and used immediately. In my case, this injector would be sitting there with a full-on mixture of 12 parts vinegar and 1 part FP. I'm in Kansas where we are likely to hit 100 degrees during the summer. Is that going to be safe and effective or can the vinegar somehow "ruin" the fertilizer?

You would be defeating the purpose of a well draining mix by preventing water from escaping creating perched water and yes, damaging your roots. Your concerns about water usage are valid. I have a well too, and have to be very careful about water usage. A few things you can do: Use larger container and a slightly higher proportion of peat in 5-1-1. That will reduce your watering frequency, but will require more water at a watering time. Save exiting water and use it on your gardens. Will reduce need for water and fertilizer there. Capture rain from your roof in barrels or a cistern. Plants love it. Some people use grey water. I use that in ground, but not in containers, but I think it could be used. Use a drip system. It's more efficient then hand watering. Use self-watering containers (earthtainers). The whole concept of earthtainer is to conserve water. Mulch your plants. It reduces evaporation. Use plastic or hydroton or white rocks to reduce evaporation a lot. Be careful though as reducing evaporation can increase root temperatures. Use white containers.

coco does not disintegrate, it resist decomposition and last several years.. i have made a quick video showing how airy it is, and it's certainly not "dust" like it's mentioned in that 2 line sentence about the person in that link you posted say it is, and as i've said, coco can be purchased in coarser grade too. i'd imagine mixing the finer grade coco with the coarser coco would make one hell of a mix that will put the 5-1-1 mix to shame and keep so much money in your pocket.. but i think just the normal texture coco is fine, there are plenty of people who use it on thehotpepper forum by itself with amazing results. it does not compact at all despite how hard it is squeezed. very fibrous which is why it does not really need any additives such as perlite, bark, etc..which saves huge amounts of money. the amazing thing about is it has tremendous water holding capacity while still staying light and airy and not suffocating plant roots. there are so many other reasons why it's superior to just about every type of planting media out there. research and very much doubt you'll find many valid negative things about it.

My experience with the particular plants you mentioned is nil because I live in a cold zone where we can only dream of growing plants like these, but my general approach is to plant anything woody or perennial in gritty mix. There's no reason you can't use 5:1:1, but it breaks down quicker and therefore you have to repot sooner than with GM. The only exception for me might be if you have a very large container. Unless you have a cheap source of bark in exactly the right size, making gritty mix in my experience is a somewhat time-consuming process (or expensive to buy already screened material). I have a couple of mandevillas in huge planters, for example, and I use 5:1:1 even though I overwinter them.