Spring aeration, over-seeding, pre-emergent.
I have noticed a few signs advertising aeration and over-seeding. It’s almost March now and that got my attention. Couple things to consider. First, over-seeding should be done in fall. However, due to last season’s dry spell, many non-irrigated lawns where too dry to core aerate. Many lawns are now in poor shape with bare spots and weeds. Here’s the caveat, starting around February most will spread their first pre-emergent/fertilizer application. (Crab grass starts to germinate when the ground temperature reaches around 55°F for three consecutive days).
This pre-emergent creates a barrier just above the soil to prevent crab grass and other weeds from germination. When you core aerated that barrier is now compromised. Which defeats the purpose of putting it down. Furthermore, if you over-seed the pre-emergent will inhibit the new grass seed form germinating. The pre-emergent will kill the new grass.
New grass needs time to get established. That’s why fall is a great time to over-seed. It should give the new grass enough time to germinate, grow, get mowed before a hard frost, go dormant over winter, and start growing again come spring. All this in what should be a cooler time of year. When new grass is sowed in the spring. It is most likely going to be subjected to the heat and dry conditions of the summer months. This will stress the new grass and it may or may not survive the season? Mostly due to it’s root system not being deep enough yet.
Winter/Spring over-seeding. Providing you have not applied any pre-emergent to your lawn this season the next consideration is addressing weeds. If you just has a couple smaller areas of lawn that need seeding you can simply avoid the application of pre-emergent to those spots while treating the rest. However if your whole lawn is in need of repair you’ll be dealing with some weeds. There are many herbicides you can use to address weeds which will come up during the season. However there is one weed that may prove to be an issue, Dallisgrass. This particular weed is difficult to manage with the given herbicides on the market. In it’s initial stage it looks like crab grass. Yet it quickly produces stocks with seeds. Then when you mow those weed seeds spread. One method, if you don’t have a prolific spread of Dallisgrass, is to simply dig the weed out.
Core aeration and over-seeding is a great practice to get your lawn in shape. Understanding when and how to use this method will save you time, frustration and money.
You can over-seed in the spring, although not the ideal time, just beware of the additional work required to get your lawn back in shape. Or just wait till next fall and renovate your lawn then, while working on what you do have established.