If you are having troubles with aphids here is a quick, cheap and simple solution that I used to clear up my problem with aphids.
Buy a spray bottle ($2-4)
Buy the lightest dish soap you can. I got Palmolive Pure and Clear Liquid Dishsoap from Kingsoopers/Safeway/Walmart. ($3)
And hopefully you have Cayenne Peper, otherwise your gonna have to buy that too.
Now adjust the PH of your water to 5.5-6 in a bowl. Add 1 tsp soap, 1 tsp Cayenne pepper to the bowl of PH adjusted water and mix. Then pour into spray bottle.
Now twice a day spray below and on top of your leaves and on the stems. This cleared my problem up in a week and now I'm aphid free.