Dig That Crazy Mixed-Up Lawn!
"My lawn is currently fescue that gets half a day of sun and half a day of shade as the front of the house faces East and the back west. The majority of the front lawn gets AM sun and the back gets the PM sun. I have a couple of bare spots I want to address this fall and plan on running a plug aerator over the entire lawn, roughing up the bare spots, then overseeding and spreading topsoil. I am wondering if it would be OK to overseed with a bluegrass that will spread via rhizomes vs fescue, which as you know, does not spread to fill in its own bare spots.
"Thanks! You used a previous question of mine on your show; your advice worked like a charm and remedied the issue!"
A. Thank YOU for the positive report, Keith; we love hearing back when our advice works!
Anywho, I realize that the perfect time frame for working on cool-season lawns is running out, but your soil should still be warm enough to germinate new seed fairly rapidly. And yes, dear listeners, while I did try and avoid electronics other than my pinball machines over our summer hiatus, I did scroll through and briefly answer a few emails here and there, Keith's being one of them. It simply said "Fescue. It may mean a bit of work every other fall, but it's your best choice". Now I get a chance to explain why.
But first, of course, a diversion. Keith mentioned that he planned on performing a core aeration before doing any seeding and I want to take a moment to highly recommend this. A core aerator is a machine that pulls plugs of soil and grass out of your lawn and makes your arms shake for several days afterwards. You can rent one, but be aware that they are big and heavy; it's not the kind of thing you can fit in the trunk of your car. Any reputable lawn care service will be happy to come out and do the job for you. Hint. Hint.
Yes, it sounds counter-intuitive to pull those plugs, but the second biggest human cause of lawn death is soil compaction, especially if you have a large riding mower. Big machines and heavy feet compress the soil over time, making it difficult for air and water to reach the roots of your turf. The best solution is to pull out plugs, thus reducing the overall density of the soil.
And yes, plugs MUST be pulled. Years ago, we were offered the option of The Sandals of Death; sandals with long nails on the bottom. Walk on your lawn wearing them, it was touted, and the nails would make holes in the turf, which they did, but with no material being removed, the holes just filled back up with no reduction in soil density.
An interesting digression. Researchers testing the sandals discovered that you could kill huge numbers of grubs and baby Japanese beetles if you walked on your lawn wearing them at beetle emergence time in your region; information your local Extension will gleefully provide. Just saying.
Oh, and if you were wondering, poor watering practices are the number one human cause of all plant death. But that, children, is a story for another day.
Timing is important here. Cool season lawns like fescue and bluegrass should only be aerated in the Fall, ideally September through October. Aerating in the Spring would weaken the grass right before the hot summer weather hits.
Same reason for the timing of seeding and overseeding. In the Fall, the soil still retains a good amount of that summer heat, which makes for speedy germination.
The cool season grasses that emerge then love growing as the nights get cooler. Spring sowing is a waste of time, seed, and money in most regions as the soil retails the winter cold and the seed can't readily germinate. The opposite is true of the warm-season grasses grown in warmer regions; aerate and install them in the Spring and leave them alone in the Fall.
Back to Keith. (Remember Keith?) My impression is that he started with a named variety of fescue or a named blend of various fescues that look similar to each other. It would be really difficult to ballpark guess a bluegrass that would match the existing fescue. But it would be really easy to pick a variety with a distinctly different color and blade shape, leaving you with a crazy quilt lawn.
That's why I always advise starting a new lawn with a named variety, so that you can match the seed in the future. And fescue is the better choice. It requires less food and water and holds up better under foot traffic than bluegrass. Just plan to reseed any bare spots in September and then spread an inch of finished compost over the entire lawn to give it a natural feeding and you'll have a great-looking, kid-and-pet-friendly turf.
