Question
Without using Roundup and other herbicides, what is the best method to control crabgrass, dandelion , thistle, etc. and still have a green lawn?  

Answer
Hi Henry;
If you want a dessert, use Roundup.
It kills EVERYTHING it touches, weeds, grass, flowers, trees.
I haven't use a chemical in over 10 years, and I used to have crabgrass, dandelions, johnson grass, clover, dollar weed.
Going on an organic program did it.
I spend a mere fraction of the money, and less than 1/4th the work, and i have a gorgeous weedfree lawn, and garden.
Here is my program.
Bear in mind, that if ou oput any chemicals fertiliozers etc on the lawn, it will kill the micro-organisms, thereby cancelling out all the benefits of the organics.
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You will constantly improve your soil if you go on a totally organic program, and don't use any chemicals at all.
I have beenm on such a program for the last 9 to 10 years, after breaking my back and ruining my body trying to maintain a decent lawn, with only mediocre results.
the organics has freed me from about 90% of the physical work, about that much of the expense, and the results are a think, beautiful yard with no weeds or harmful insects.
Man!!! Wish I had known all this 50 years ago !
The corn clutem meal is an organic product.
If you use organics, and then use chemicals, you will cancel out the organics.
Chemical fertilizers kill all the beneficial microbes, nematodes and other beneficial insects and critters that work around the clock improving your soil.
Beneficial microbes enrich the soil. Chemicls do NOT.
If you put a little too muchj chemical products on the lawn, it will burn your grass, and do a lot of other damage.
If you put too much organics on it, all you do is waste a little time and money.
Sugar does absolutely nothing but nourish the beneficial micrebes. THEY do the work.
Weeds will not grow in rich soil. If they cme up, they will start to die out right away.
The first time I use sugar was in the spring. I had not put any chemicals on the yard since the fall feeding, so they were all worn out of the soil.
I had a lawn about 50% full of dandelions, crabgrass, johnson grass, clover, dollar weed and some other shallow rooted weeds like chickweed etc.
a couple of weeks after I put down the sugar and watered it in, I had about half as many weeds. Nobody had pulled a weed or anything. My husband had just mowed.
I went nuts, like a school of sharks in a feeding frenzy, and ran out and bought more sugar, put it down and waterewd it in.
A couple more mowings, and there were so few weeds. In a few more werks they were all gone.
The next spring about half as many weeds as before came up, but in a few weeks they were gone.
All I had done was the sugar in the spring, and I did that again in the fall.
I used baking soda disolved in water for black spot on my roses and powdery mildew n my crepe mytrtles. That works much better then the chemical fungicides I had used before.
I started getting a nice herd of lizards, toads and grass snakes in my yard.
I had a BIG grub problem every year. I haven't had that since, nor do I have those nasty tent catapillars dropping on my head from the trees.
I see lizards running in the trees and along the fence. I never see the grass snakjes, which is fine with me. I seldon see a toad, but they are all there.
Sugar; I use 4 or 5 pounds per 1000 sq.ft. I just broadcast it by hand, and water it in well. If you spill a blob in one spot, no problem. No burning or other damage.

Watering; I always water to a depth of at least 6 inches. Deep watering like that encourages a deep root growth. That protects from heat, cold and drought damage, and prevents thatch. I water with soaker hoses, and run them till the water is close to the edge and is about to start running off the yard. then I turn it off and wait an hour or so for it to soak in, and turn it on again. I keep doing that until it is wet down to a depth of 6 inches at least. Even here in our Texas heat, I water only once a week, unless it stays well above 100 for a week or more, which it sometimes does. then I look at the grass, and if my St. Augustine is folded up, lengthwise, I know it needs water. It folds the blades up to reduce the area exposed to evaporation. Burmuda, when it gets thirsty, bends it's little blades a little, like it is bowing.
My earthworms and cock roaches etc tunnel through the soil, and that keeps it aerated. Their castings add nourishment. Cockroaches are beneficial. They normally live in the soil and feed on other harmful insects. We put down pesticides, and kill their food supply, so they come in our houses to get food and hide from the pesticides.
I use fresh rosemary to keep them out of my house.

Baking soda disolved in water, about 2 TABLESPOONS per gallon of water, sprayed on top and underneath all the leaves, prevent molds and fungus on plants. You can also use it for fungus in the soil, or you can apply agricultural corn meal and water that in. About 10 pounds per 1000 sq.ft.

Corn gluten meal is an organic fertilizer and weed killer.
It won't interfere with the sugar.
None of the organics calcel each other out.
Alfalfa meal is another good food to add. Just sprinkle it on in about the same thickness the sugar goes on, and water. It is full of nutrients. So is lava sand. Yopu can add it to the top of the soil, dig it into the soil, or add it when you are adding soil, or putting soil in a comntainer for a plant.
Alfalfa meal, as well as generally nourishing the soil, helps promote larger and more blooms in blooming plants and house plants.
You can also make a tea of it for foliar feeding or for watering house plants.
Put 1 cup alfalfa meal in 5 gallons of water and let steep overnight. Still and use to water plants, or strain it and put it in a garden sprayer for foliar feeding.  Be sure, if you strain it, to dump the dregs on the soil somewhere, it is still full of nutrients.
You probably won't need more fertilizert than that. I didn't use anything but sugar for about 8 or 9 years, and last spring, I leartned about the alfalfa meal and lava sand, so I use them.
If you have more questions, write to me.
I am very happy to share what I have learned, and am learning.
Charlotte