Killing of Daylilly grass, can it be done?

[Ed]

My wife planted a Happy Returns daylily in the front garden a few years ago. The rysome grass the plant gave off choked out all the surrounding plants so we tore up the garden and started fresh. When the landscaper put in the new mulch/stone he never tilled the soil and now the rysome grass is coming back. I've tried Roundup and Ortho vegetation killer but it only kills the blade it hits, the underground network continues to flourish. Short of starting everything from new again, is there a way to kill off these invasive grasses? Thanks for any help. Ed

[David E. Ross]

I'm very confused.

What is a rysome? Do you mean rhizome? Or do you mean rye grass?

Daylilies are NOT a grass. They grow from bulb-like tubers, not rhizomes. Mine grow quite lush but they do not spread wildly and are not crowding out adjacent azaleas, cheddar pinks, thrift, cinquefoil, or pink clover (persicaria). Indeed, the latter two (both ground covers) would choke out the daylilies if I did not keep trimming them back.

If Roundup is killing only the foliage of any plant and not the roots, you are using too strong a mixture. The standard dilution is to add 6 oz of concentrate to 1 gal of water (about 1:21.3). Try using a dilution of 4 oz to 1 gal and repeat in 3 weeks.

[Elizabeth]

I would guess that he got some bermuda mixed with his daylily. I agree with RoundUp