I also live in Florida (Tampa area) and am currently battling weeds in my SA lawn. I do not mulch mow and bag the clippings - I feel that it has really helped so far in preventing seed dispersal. Before I mow, I try to remove as many seed heads as possible. Some weeds such as wood sorrel will get high enough to be drawn into the mower and it takes very little agitation for wood sorrel's seed pods to burst open. Chinch bugs took a toll on my lawn over the summer, in which the weeds quickly took over the bare spots. I know its a slow process for the grass to recover (considering replacing some of the lawn with groundcovers LOL)

Consider. Weed seeds move about the universe on the wind, in bird droppings, and by attaching themselves to the fur of animals that transport them to new areas so mulch mowing your yard is not going to contribute that much more to what comes in from elsewhere. The presence of unwanted plant growth ("weeds") may be an indication of a problem that needs to be looked at.

kimmq is kimmsr

Yes, weeds come from many sources. But there is a higher probability of seeds in one location germinating in the same location, especially weeds like wood sorrel/oxalis and purslane whose seed pods burst open when disturbed such as when mowing. Bagging the clippings or hand pulling the seed heads before mowing will definitely lessen the chances of dispersal. After the initial cut, continue with high and regular mowings to keep future seed heads forming. However, some weeds like purslane and oxalis will still form seed heads below the mowing height and will require hand removal or spot treatment. After that, mulch mowing (as well as applying organics) would be recommended to improve the health of the SA.

OP: Yellow nutsedge spreads by underground rhizome and tubers and is incredibly tough to remove, especially organically. I don't know of any organic systemic herbicide that would work on nutsedge - perhaps someone on the forum can chime in. I know of only chemical methods in which you spot treat each plant. As far as crabgrass, it spreads by rooting as well as seeds, so minimizing seed production is recommended. I am currently experimenting with baking soda/soap/sugar solution and so far there has been success!

I've been using molasses for nutsedge. Cut the nutsedge down to the ground especially so there are no leaves/blades. Then cover the cut stem (should only be a little nub left) with molasses. Clip a few here and there and it adds up. If your nutsedge is growing more in grassy clumps, then just cut the clump down and pour molasses over the top.

If you have pure weed areas, 20% vinegar works very quickly. It will kill anything it touches. It will start dying within hours.

I've been mulch mowing. My turf has really thickened especially now that it's fall and the stolons are spreading much more quickly.

The weeds have been filling in thin spots and bare spots where nothing grew before. I have not seen weeds being invasive; they are not smothering and replacing the grass. But I keep an eye on it. We'll see. When I keep the lawn mowed it just all looks like a thick carpet of green from a distance. So I'm happy.

I see the St. Augustine competing strongly and winning the lawn. So at this moment, I believe nourishing the St. Augustine is more important than trying to punish the weeds.

I have been mulch mowing my lawn for 40 plus years and I see no increase in the number of "weeds" although there is sometimes different types of them in the lawn. The idea of bagging the clippings comes from the people that promote the use of synthetic products, not from true organic growers.

kimmq is kimmsr

M.Adams....thanks for the tip on molasses for nutsedge. Do you know if it kills only top growth or does it work systemically? Those underground tubers are little storehouses of energy. Being near the coast have you tried harvesting seaweed? I've done it and have had good results but it is time consuming. I usually take the easy route and spray with kelp during summer months which helps with heat stress.

The theory I read is that the molasses causes a blast of bio activity that rots the nut. But I've never gone digging to test. The nut sedge has not returned or multiplied so it's very promising. I know it's important not to break the sedge from the nut, but the molasses does seem to rot.

I came up with the method because people were diluting the molasses and spraying the lawn. They said it didn't work, but of course it wouldn't. Diluted molasses is just like fertilizing. When I read the theory of the high bio activity rotting the nut, I realized that cutting the sedge down and applying pure molasses with no dilution would fit the principle better.

I stick to liquid kelp as well. I mix it with fish emulsion. I overhead water my shrubs and flowers with it and do put it on my lawn as well. What's your process for administering? I've just walked around with watering cans but am considering an EZ Flo system.

I can imagine the beautiful results from fresh seaweed.

Two of my lantanas were ravaged by hurricane Matthew. The leaves just withered and turned crispy brown. I've been pouring kelp and liquid compost and some new green growth has emerged. Unfortunately, it's so close to winter it won't harden in time. I'll replace them next spring but it's been an interesting experiment to see how organics bring them back.

What's your full organic program?

I like to experiment a lot and have no set program other than regular applications of alfafa pellets and cracked corn in the lawn and bed areas. Many of the bulk organics that I would love to use regularly such as dry molasses, soybean meal, and corn gluten I cannot find locally. I just ordered Safer Ringer Restore II which has soybean meal so am anxious to try that. I use a hose end sprayer for the fish emulsion, molasses, and kelp but do have to dilute it beforehand to prevent clogging.

Hopefully you didn't sustain serious damage from Matthew. My brother lives in Atlantic Beach & miraculously had little damage.