Ask Mr. Smarty Plants

Many of our favorite grasses, such as Schizachyrium scoparium (Little bluestem), Bouteloua curtipendula (Sideoats grama),Bouteloua gracilis (Blue grama) and Bouteloua dactyloides (Buffalograss), are so-called warm season grasses, meaning that they need a soil temperature of 55 to 60 degrees for some days in order to germinate.  For this reason seed distributors give them any pretreatment that they might need, such as cold exposure, and then recommend that they be planted in spring. 

On the other hand, in nature these grasses produce their seeds and drop them to the ground in the fall.  The seeds lie there dormant over the winter and germinate the following spring. So they have evolved the ability to survive low temperatures.  But during this time several things could happen to the seeds, some of them bad.  They might be eaten by birds, small mammals, or ants.  Erosion could carry them away. On the positive side, some of them experience that time at low temperature needed to prepare themselves for germination.

Now consider the other requirement for germination and growth - moisture.  Grass seeds need continuous soil moisture during their germination and enough additional moisture to form an efficient root system.  Most locations can count on spring rains just in time to provide that needed moisture.  But sometimes, such as in Central Texas last year, the rains don't come, and seeds do not germinate.  A similar condition in 2012 has been predicted, and that is what prompted your question.  Many of us have pondered the same question.

I'll tell you what I did.  I am converting part of my St. Augustine lawn to native grasses.  After killing the St. Augustine, I will wait to till the soil and plant seeds in the spring.  This is safe because I can irrigate that plot while the grass seeds are germinating and becoming established.  I have cleared another area of juniper and wish to replace the trees with grass there.  That area is outside the reach of my irrigation.  I decided to plant the seeds in November and take what losses to predation, etc. I must in order to gain the benefit of winter rainfall.  There will hopefully be a series of days warm enough to permit seed germination.  If not, the seeds (at least some of them) will still be there in the spring.

So I suggest that if your lawn can be irrigated, wait for the ideal spring temperatures for germination and keep the soil moist.  If you cannot irrigate, go ahead and plant as soon as possible so that the winter rains, such as we are having at this time, will give the grass a chance to get started and be able to survive a possible drought next summer.