It depends on what weeds your trying to prevent. If its crabgrass, you don't have to apply Dimension until the night time lows are 60 or above. If you dethatch kinda early, don't force the bermuda with lots of nitro. Go with a more balanced NPK with not more than 10% nitrogen and a little added iron- which will give lots of green without stressing the turf.

I get everything as far as weeds go, so I just put down my preM on a quarterly basis to make sure my "shield", as morpheus calls it, never goes away. Obviously I still get some annual Crabgrass & broadleaf & Poa, but it's significantly reduced. I'll have to see what the temps are like when we get to that point, but is there any advantage to dropping both fertilizer & preM together? My usual fertilizer for spring green up is nitrophos brand imperial which does have added iron. The rest of my fertilizer for the year are all organics.

I don't know if you have forsythia plants in Houston, but those usually indicate the correct time to apply preemergent herbicide. Whatever the first major plant/tree is that blossoms in your neighborhood is the indicator. This will likely be the very first thing you do for the lawn.

Wait to fertilize until after the initial flush of spring growth. For most people that date is in May, but in Houston it could be in April. AFTER the initial growth. - NOT BEFORE. For bermuda use a high N (low to no P or K) fertilizer on a monthly basis after that.

Watering should not be expensive. I recognize your handle, so I won't bore you with the watering mantra details, but if you want specific help with that, please let us know.

I water as little as possible, so we're all on the same page there. I'm not sure about forsythia, but around here the red bud trees are usually the first to go boom in the fall. Does that mean you'd drop the preM first, then dethatch, then drop fertilizer a few weeks later, after the grass comes back in?

We don't have forsythia in Austin. I use the redbud tree blooming as the sign to put down pre-ermergent in the Spring. Should be in mid to late February as the redbuds are starting to swell now where the buds/flowers will be forming.

I'm probably over thinking this, but will the dethatcher ruin my preM shield? I was thinking I'd have to drop dimension after I dethatch...

That's a good question. If I was going to dethatch (and I likely wouldn't) I would do that first, sweep/blow all the chaff away, and then do the preem. Fertilizer goes down at least 2 weeks after you are mowing a full lawn of growing grass. Seriously, there is absolutely no hurry to fertilize in the spring. Give the new spring growth time to slow down. Fertilizing too early is actually a problem. Perhaps in bermuda it's less of an issue, but the grass is going to come in fast and furious anyway, so it doesn't need any booster.

If/when the grass seems to come in slowly, you cannot fertilize it and make it come in faster. The best thing you could do is put a giant magnifying glass over the lawn to warm the soil. Warm soil is the only thing that makes bermuda come in faster. If you could find some black compost you could put that down to warm the soil faster. In Iowa they sometimes burn the lawn in the fall to stimulate spring growth. The black ash left on the soil absorbs the sunlight and grass comes in faster. That is environmentally ridiculous at many levels.

I like that idea of adding compost after the dethatching to warm the soil... Definitely looking at an early spring, it's 75 today!