Can Propane Gas affect the health and growth of plants?

I have several plants in my kitchen. Most are doing poorly while the rest are doing fair. My kitchen has south and west facing windows and I supplement them with several plant-style floriscent blubs....running 16 hours....as well. I have two humidifiers running to keep the kitchen at 65% humidity because the furnace is constantly running. I live in the upper midwest and it's winter here now. I also have a gas stove. Now many of the plants have poor growth habits. Stunted, misshapen and slow growth. Some even have dropped new leaves. I keep them well watered....not over watered....and at normal house temps....75-80....as well as ferderized on a weekly basis at 1/4 tsp to 1 gallon. Ortho brand. Given all this info can someone tell what I'm doing wrong?