Answer: You've experienced one of the problems with homemade solutions - they can be phytotoxic to plants. Commercially prepared Insecticidal Soaps are generally not phytotoxic because the oil is light-weight and the soap is plant derived so doesn't contain detergents. The best bet for you is to purchase an Insecticidal Soap and to use it diligently over a period of several weeks to get every last aphid. Here's the story on aphids - most are females and they give birth to live aphids in addition to laying eggs. This means that you can have several generations in different stages of maturity feeding on your plants all at the same time. So while the Insecticidal Soap will kill those it contacts, those that are not sprayed will continue to give birth to even more generations. So, thorough spraying is important; both sides of the leaves, in the nooks and crannies where stems meet and all around (and in) the folds of the flower buds. If you spray every 3 days for 2-3 weeks, you should knock out the population.
Best wishes with your project!
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