Question
QUESTION: Can I apply a pre-emergent immediately before laying sod?  I tore out a small island area of lawn that had weeds and other grasses that I didn't want.  I'm laying sod today and plan on putting down a layer of manure first, but wanted to apply a pre-emergent.  Should I do that now or wait?

ANSWER: I'm afraid this will reach you too late to be of any help, unfortunately, but for future reference and the benefit of the rest of the world reading your question, let me say this.

If you do not turn the Soil, you won't be exposing a lot of Weed Seeds to the light and air they need to germinate.  These Seeds can lurk underground for 50 years, just waiting for someone like you to dig in with a shovel and bring them to the surface.

Covering the area with Manure (which I assume is well aged so that you don't burn the bejeezus out of the Sod) will block light; Sod will seal the deal.

It is not time to put down Pre-emergents in the Northeast, but if you are somewhere warmer, let me know, and I can go into detail about this.

Bear in mind that many Weeds are Annuals.  If they don't make it to the Seed stage, they're finished.  Mowing at the right height will strengthen your Grass, often to the point where Weeds can't compete.  Let me know what you're growing, and I'll give you more information.  Thanks for writing -- I hope the Sod fluorishes.

---------- FOLLOW-UP ----------

QUESTION: Thank You!  I did place a layer of manure and the sod is in now.  And to answer your question - I live in the west (southwest).  So. California to be exact.  It is much warmer!  About 78 degrees today.  Any advice is appreciated.

Answer
In that case, for future reference, January is exactly the right time for these products to be applied to halt Weed growth.

But there are other, better ways to whack Weeds.  Because perfect timing is so critical for these to work (and you don't want to interfere with the growth of any new Grass), and because there are side effects (dead Wildlife, Birds with three legs, sterile Snakes etc) that we don't like, I just don't use them.

Except for Corn Gluten Meal, which is patented and delivers royalties to the Iowa State University that invented it.  I am not certain it would work on California Weeds.

Southern California -- probably a Tall Fescue (either Medallion or Marathon) that you laid down.  More Southern California Lawns use this than any other.

The usual Sod rules still apply.  These first few days are the MOST VULNERABLE for new Sod.  Make sure your baby Sod does not dry out!  Once established, Sod does not need as much H2O.  But even drought-tolerant Grass NEEDS to be watered while its Roots are getting established.  This is the mistake homeowners make more than any other after new Sod goes down around the house.  Don't do it.  Keep that Sod Watered the first few days; taper off gradually; let it dry out at night (to avoid Fungus attacks) and you're in business.

Correct mowing will weaken Weeds and strengthen Turf every time.  If you selected Fescue, mow it every week as early as 7 days after it gets rolled out.  Set the blades between 2 and 3 inches tall.  Leave the clippings down -- local Earthworms will devour them and turn them into rich, healthy Soil.

If your plot can be managed with a rotary Lawn mower, I recommend one of the calorie-burning, German-built precision instruments made by Brill.  They are discounted on the internet and make a sharp, clean cut every time.  No noise.  No exhaust.  Easy to adjust.

Please confirm your Grass and I can go on and on...