Here are some problems that people commonly have with their plants. Check to see if you have one of these problems before suspecting anything else.

1. Improper mixing of nutrients or nutrient deficiencies (read directions)
2. Bugs and pest (use environmentally safe controls)
3. Letting plants dry out (water manually if necessary)
4. Improper or not enough Light (use 500 to 2000 foot candles)
5. Wrong temperature (keep between 65 and 95 F.)
6. Improper humidity (mist or spray, except cactus)
7. Improper pH (keep between 5 and 7 for most plants)
8. Toxic elements in water, system, or growing medium (don't use galvanized metal, copper or brass)
9. Bacterial or fungal infection (keep clean and sterile)
10. Waterlogged roots (no standing water in grow-beds)
11. Toxic salt buildup (flush with water every 2 - 3 weeks)
12. Pets urinating, etc. (keep pets out of growing area)
13. Spilling concentrated nutrients or pH adjusters (don't)
14. Windblown herbicides from neighbors (wash off)
15. Improper aeration (provide better drainage, aerate)
16. Experimenting (don't deviate too far from instructions)
17. Location changes (light, temp., pH, etc. can stress plants)
18. Freezing or wind damage (prevent and protect plants)

There are any number of other reasons for plants dying or not doing well. Sometimes you have to turn into a detective. Don't be afraid to ask questions!