This is cheap and effective, but it is not for edible crops. It says right on the front it is for ornamental plants. Who knows what kind of effect it is having on you. I am all for saving money, but truthfully its not worth saving a buck if its harming me in the long run. While hydro stores can be a bit expensive you will find the correct products rather than whatever is available. Home Depot, Lowes and even a lot of local nurseries are buying these products for the person maintaining their landscapes, not people growing edible gardens. Also go ask someone at Home Depot what works best for aphids, they will have no idea what an aphid is. If you ask the same question to the people working at your local hydro store they will usually have an educated answer to your issues, and that is worth the extra few bucks. Plus you will be supporting a small local business rather than a large conglomerate who only wants your money, they don't care if your garden stays infested.
As for
diatomaceous earth, it may have some efficacy but only for anything trying to find its way into or out of the soil. Neem is not bad, I would personally step up to something like
Azamax; its a more concentrated form of the chemical within neem that kills pest. However for aphids I do like some thing a bit stronger like
spinosad or
pyrethrin, both are safe for edible crops and are often listed as safe to use in organic gardens. Then there are plenty of options that are based on essential oils, like
Trifecta,
Lost Coast Plant Therapy or anything from
Sierra Natural Science (SNS) that seem to be effective, but do typically require a few extra treatments. I personally apply combinations of all of these when I have pest problems.
If we only continuously use a single product to attack pests eventually the pests will win. Most people call these super-bugs but this is not true. All organisms have natural immunity, but not all members of a population have the same set of immunity. So some of the bugs will succumb to one treatment, lets say
pyrethrin, but not all will be killed. A few of those bugs were immune to
pyrethrin, and at least 25% of their offspring will have the same immunity. So when we come in a second time with the
pyrethrin we may only knock down 75% of the population, then on the third application we only knock down 62% of the population and this will repeat until the only pests left are the ones with natural immunity to
pyrethrin. So if we do a
pyrethrin treatment, then a
spinosad treatment 4 days later, then a
Plant Therapy treatment 4 days after the
spinosad, we will have eradicated pretty much everything and attacked any potential immunity and we should no longer be dealing with pests.
Once the pests have been minimized or eradicated then I use something like
neem oil once a week (in veg only) to keep the pests from returning. If I can avoid it I try not to spray anything on my plants once they have begun flowering. Only if I absolutely need to will I spray plants in flower and at that I will not spray them past day 21 of bloom.
But truly the best way to fend off pests is to have strong healthy plants. Like us, if the plants are healthy they have immune systems that will kick when they become infested with bugs. With strong plants they will fend off the attack on their own or take little damage from the plants. One of the things you can do to give the plants immune system a bit of a kick is biweekly treatments with insect frass. The insect frass causes the plants to start producing chemicals within itself to repel bugs that want to come feed on them.