Corn Gluten Meal is a pre emergent and needs to be spread about 6 weeks before weeds germinate at a rate of around 20 pounds per 1,000 square feet. That may be now depending on just where in Texas you are.
Vinegar needs to be sprayed on actively growing unwanted plants, but it only kills top growth so the roots left behind can grow again.
How much of any "fertilizer" to use depends on what the soil needs and a good reliable soil test from Texas A & M Cooperative Extension Service could be a big help determining that.

what kind of grass do you want?

in houston they are "big" on st augustine. I live in houston.

you say your yard is 95 % weeds. you can't just rip out the weeds without planting something in its place. nature abhors a vacuum and will send in its healers, like clover or prunella, just to cover the dirt.

i assume you have some st augustine under there somewhere? mow the grass at 4 inches, fiskars mulching reel mower, corn meal sprinkles once a month when the grass is dry. organic fertilizer, compost tea in a sprayer. diluted molasses in a sprayer.

you want to encourage the growth of the st augustine. happy st augustine will crowd out the weeds in a healthy soil.

if you don't have st augustine, you may need to buy some sod. so... what kind of grass do you have?

be patient.

read this: http://faq.gardenweb.com/faq/lists/organic/2004020829016580.html

and this: http://faq.gardenweb.com/faq/organic/

my front yard was in good shape.. i hand pulled all the weeds and sprinkled heavy corn meal in all the raw dirt areas, and all over the yard. i mowed at 4 inches and put a nice edge. yards looks nice with a nice edge, even if they are all full of weeds.

then last weekend i sprinkled scotts organic fert: blood bone, and protein meal all over the yard. today i will do a dilute molasses spray and next weekend i will do a compost tea.

my backyard is horrific, like yours. here is my plan. hands and knees hand weed (steak knives are handy) and heavy corn meal one square meter at a time. and continue as above.

edit: i ended up just hacking at it with a lawn mower and a steak knife for the deep rooted perennials. there is augustine underneath.

now i will follow the corn meal, organic fertilizer, molasses tea, and compost tea regimen.

and hand weed when i see 'em.

feed the soil, not the plants. feed the earthworms, not the plants.

This post was edited by ladykemma2 on Sat, Mar 29, 14 at 15:18

Sometimes a yard is so far gone you have to take a step back before you can take a step forward.

Although I've been a dedicated organic gardener for years, I would find the task of clearing a yard comprised of 90% weeds too daunting to address naturally.

Were I you, I would simply buy a sprayer and concentrated broad leaf weedkiller. Spray the entire yard and kill the weeds. Once dead, you can then switch to an organic program that, when applied correctly, will eliminate the need to ever use chemicals again.

Spraying a synthetic "weed" killer is not an acceptable alternative to anyone wishing to begin an organic growing program. Synthetic "weed" killers do more harm to our environment then any benefits of quick plant control might provide, long term damage.
To establish an organic lawn a good start is with a good reliable soil test that will tell you what that soils pH and levels of major nutrients are. Also a need to know item is how much organic matter is in that soil. So along with that good reliable soil test perhaps these simple soil tests will be of some help,
1) Soil test for organic matter. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drainsâ too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

CanCan100, your thought's are all over the place! You need to take a step back and come up with a plan. First, even at the date you posted it was too late in TX to apply CGM as a pre-emergent. Timing is critical. It should be put down when the Forsythia blooms or if there are 3 consecutive 50* days (whichever comes first). Also, be sure there is no big rain for 2 or 3 days after the application. Also, be sure it is certified CGM, with approval from Iowa State University, not just from a feed store. The concentrations are not the same, and much of the reason people think CGM doesn't work.

Beneficial Nematodes aren't cheap, I should know, I just had to purchase them to address a grub problem. But why are you wanting to use these? Do you have a grub problem? If not, don't waste your money.

90-95% weeds = Kill the lawn, but I agree with Kimmsr, do not use synthetics. It's unnecessary, and will set you back in your pursuit of organic lawn care. Instead, I recommend picking managable sections starting with the front yard and Solarize it! If you do it right using the hot TX sun, EVERYthing will be dead, just in time for fall planting season.

Next fall you would be ready for a fresh start. You could add a nice layer of compost/topsoil mix and then seed like crazy. Before winter you would have an awesome looking yard, then your organic lawn program can really begin...