I have used Pre-emergents in my garden for many years. Once I tried Gallery but it didn't work as well for me. I have used Preen. I prefer Snapshot - it seems to work a bit longer.
As soon as the beds are cleared off in the spring, I put the pre-emergent down on the beds, top with pine bark chip mulch (if the bed needs mulch) - then make sure the area gets between 1/2" to 1" of rain or watering in the next couple days to activate the chemical. Although I still have weeds, I think they are greatly reduced when using the pre-emergent. I seldom get around to applying Snapshot during July to control fall weeds. Daylilies are blooming in July and I neglect everything else during that time.
I have heard that pre-emergent will stunt roots, inhibit growth on seedlings and adult plants. However my plants seem perform equally to other gardens around.
I once tried rolling out weed mat in a new bed - then cutting holes in it to plant the daylily - but I found it was a real mess to try to get up a few years later when we wanted to add amendments and till them in. I finally gave up and just moved everything to a new bed. Eventually, grass took root in the old mulch and now we just mow over the area. But I won't be putting that stuff down again as weed control around daylilies. I do use weed mat around my garden tomatoes, cukes etc - but I remove it that fall, before it breaks down.
I will try to get some photos of the tools I use for weeding. I have tried quite a few over the years. Some work well - and some were, in my opinion, a total waste of money.
I do use mulch. I like the smaller pine bark chips.
I have also used Roundup, and sometimes 2-4-D. Fuscillade (sp?) helped get the nutsedge under control. I use big sheets of cardboard to shield the daylilies and perennials when I am spraying. I learned that the slightest bit of over spray from Roundup or 2-4-D will ruin the rest of the buds on a scape. So I try to limit any spraying at all to early spring, or after bloom season.
Right now, I am having problems with wild onions in the daylily beds. ARGH!
Back when I was younger, and healthier - I just pulled all the weeds by hand. I actually enjoyed weeding! Now -- it is difficult, so I have resorted to some other means to combat weeds.
I would like to hear how you battle weeds in your daylilies - and in any veggie garden or perennial gardens....