Answer: It's normal in late summer for the bottom leaves of heliotrope to die down. As long as the rest of the plant looks healthy, the yellowing of the lower leaves isn't anything to worry about. I'm concerned about your watering practices, though. When you apply only a little bit of water on a frequent schedule you'll encourage the plant's roots to stay close to the surface where they will depend upon frequent watering, instead of growing deep down into the soil where they will find ample moisture and be less inclined to suffer from heat and drought stress. When you water, you should water long enough to allow the moisture to penetrate the soil several inches deep. This is typically 15-20 minutes with a standard sprinkler and average househould water pressure. Watering long enough to saturate the soil will allow the moisture to trickle down, wetting the entire root mass. I would water once or twice a week, allowing the sprinkler to run 15-20 mintues rather than lightly sprinkling for 4 minutes a day. You'll find your plants will grow lush and thick and be healthy enough to tolerate some damage from garden insects.
Hope this information is helpful!
Q&A Library Searching Tips