Mistina, what are you hoping to accomplish with this mixture? What is it supposed to do? The problem with many of these so called 'natural' or organic home remedies is that they really don't do anything despite being touted for all sorts of magical properties. Corn meal - or even corn gluten meal - really doesn't have significant herbicidal or fungicidal properties. Scientific testing to support any consistent herbicidal properties have not been able tosuccessfully duplicate the results generated by Iowa State University that caused all the hoopla to begin with. And the fungicidal properties simply do not exist. But since CGM is nearly pure protein, it's not at all a bad organic fertilizer (if you overlook the consideration that most feeder corn grown in the US is GMO'd). And Epsom salts (magnesium sulfate) provides absolutely NO benefit to the garden unless you have a magnesium deficiency in your soil. If you want to use any of these or similar organic home remedies for weed control or pest or disease suppression, do some research first before you spend money purchasing these products needlessly. There are numerous websites outlining any scientific testing or investigation into the alleged beneficial properties these products may or may not possess. Look in particular for scientific papers or websites with the .edu suffix. Finally, purchasing food grade equivalents of these products at a grocery store will always be more expensive than buying in bulk from a feed lot source.

To answer you question: Sure you could use Corn Gluten now, unfortunately most of use have found it doesn't work very well as a pre-emergent. However it is an excellent fertilizer. The pre-emergent results vary greatly and for the cost, I think you will be disappointed. With an organic approach your going to have some weeds, thats a fact. Now, there are some things you can do to limit the amount of weeds you have. Proper management practices that encourage a dense, thriving turf are the best method of weed control. Healthy turf shades the soil so sunlight can't reach weed seeds ready to germinate. A thick turf also minimizes the physical space available for weeds to become established. There are several management practices that will promote a healthy, dense grass. Proper management begins with selection of the best turf species or variety for a particular area. For example, heavily shaded areas will support only a few turfgrass species. This results in thin, weak turf that is very susceptible to weed invasion. Do some homework before you overseed this fall and find the best variety of seed for your area and "shade situation". Proper fertilization, watering and mowing are required to produce a dense turf that will prevent weed infestation. If turf is over-or under-watered, over-or under-fertilized, or mowed too low or too infrequently, the turf is weakened and cannot compete with weeds. Damaged areas resulting from using unsharpened mowers increase time needed for turf recovery, allowing for weed invasion. It is very important to understand that weeds don't create a void, they fill a void. So, first, Set your mower to its Highest setting and leave it there. Always use a Sharp blade Irrigate with 3/4" of water when 30-50% of the lawn shows signs of stress. In the shady areas you might be able to go weeks between waterings. The general rule of thumb is no more than once a week in the middle of summer. This is the most important step IMO. To determine how long to run your sprinkler system to apply this much water, set out several straight-sided, same-size cans (tuna cans work best) at random in each irrigation zone and see how long it takes to fill them to the desired depth. Be sure to check your irrigation system for uniform coverage at the same time. In the meantime get yourself a Weedhound(google it) or hand pull the weeds. You could also CAREFULLY spot spray the weeds with vinegar.

Yes it is perfectly safe to use both at the same time. In fact it is safe to use any of the grain type fertilizers at any time, day or night, rain or shine, all together or separately. There are no interactions among any of them that we know about. You can use them in amounts up to the smothering the grass stage (more than 50 pounds per 1,000 square feet). You will get some bad odors if you use more than 30 pounds per 1,000 square feet but if you are using corn and corn gluten meal at 10-20 pounds per 1,000 square feet, you should be fine. Where it might get dicey is if you used blood meal or fresh manure in large quantities. Personally I would never use fresh manure without full composting first. Blood meal is probably best used by mixing it with grains so that no more than 5 pounds per 1,000 square feet of blood meal goes out. Blood meal can get stinky fast and it can burn your grass roots. It is hard to control very light applications of it so mixing it in with something else is a good idea.

IF you are going to use a chemical "weed and feed", better carefully read the label as the product will kill a lot more than weeds. Also, contrary to popular belief, St. Augustine needs 5 or 6 hours a day of sun shine. Now, before Lou starts in about shade tolerant varieties of St. Augustine, yes, there are some new strains, they are expensive and it involves resodding your lawn. To reiterate about CGM, an application of less than 20 lbs. per 1,000 sq.ft. has limited effectiveness, and a heavy rain immediately after application will render the weed killing effect nill. If your desire is to use a natural approach, you need to understand how products work and what to expect of them. Most of the grassy weeds will die out in the heat. Others will be crowded out as the grass regains its vigor as it comes out of dormancy. The best way to control a lot of weeds is with a healthy lawn. Further, I have been praticing organics for 50 years and my present property for 35 years. Don't expect a property to turn around in 1 or 2 years as it will take that long at least to get the toxics out of your lawn and garden.