rich soil poor soil

Does anyone know of a chart or similiar graphic that helps a novice gardener better understand the terms that are often used (and sometimes confuse) on seed packets and advice sites. Most of my container plants are said to like "a rich" soil but now Nasturtiums like a "poor soil". I've been using Schultz's Potting Soil Plus which I assume is rich but have no idea what to report the Nasturtiums to. I always thought rich and poor was about nutrients (not sand, silt, clay) but think some sort of chart or graphic would be helpful. Thanks in advance for any help you can give.

good question. I have assumed it goes along with organic content, as well as nutrients. more organic being richer.

Sorry for the belated response, but I haven't been to the forum much since I acquired chickens.

Nasturtiums are fine in just plain "dirt". For plantersand pots I mix equal amounts of potting soil, sand, and either coco fiber or peat. Too much nitrogen and your nasturtiums will produce a lot of foliage, but fewer blooms.