Answer: The solution to your problem depend on which leaves are turning yellow. If yellowing is occurring on the young leaves (those near the end of new growth), iron deficiency may be the cause. Chelated products work well when applied to the soil beneath the plants. You may also want to try using Miracid as it contains iron and will help acidify the soil a bit as you fertilize.
Adding lots of organic amendments to the soil before planting can help alleviate the problems caused by a high pH soil like yours. I find that even with a high pH, when there is plenty of organic content, the plants do well and exhibit little iron deficiency.
If the yellowing is occurring on older leaves, the culprit could be over or under watering, lack of nitrogen (which I doubt, based on your regular use of Miracle Grow), or root damage as can occur in transplanting or deep rototilling around an established plant.
Q&A Library Searching Tips