I too use Preen and Snapshot. I don't think there is product that gets ALL the weeds, but Snapshot has 2 active ingreients in it. The Trifluralin that is in both is higher in Snapshot than Preen. What I've been told is Snapshot helps get the winter weeds that Preen doesn't get. I really couldn't tell a difference. What I do is after I'm done planting a bed and know I won't be messing in it anymore then I sprinkle it down on top of the beds and water it in.
I still have a few weeds here and there especially if I pulled some of those really small, but abundant weeds that leave some of the root behind when you pull them. You can definitely tell when it has quit working and it's time to put more down. As long as I keep track of when I apply it and reapply when I should it works great. I have seen no stunt roots or inhibited growth on seedlings or adult plants. Now, if you put it on a bed that you've direct sowed that's another story. I have heard that someone did this not realizing it would keep the weed seeds from germinating as well as daylily seeds and not one single daylily seed sprouted.
I use Killz All (same active ingredient as the professional roundup but cheaper than the regular roundup) and 2-4-D ( Weed-B-Gone) to spray around the daylily beds. When I have sprayed in the daylily beds, mainly for dollar weed, I taped a water bottle cut in half onto the spray nozzle so there wouldn't be any overspray. I have used cardboard to shield them as well.
I did get some over the top grass killer that is labeled as use on daylilies (ingredient Sethoxydim sp?) but never had to use it.
To keep ahead of the weeds, as I walk the beds, if I see a weed I go ahead and pull it. If I do this everyday while I'm out there it doesn't seem to get ahead of me. If I put it off and say I'll spray later, by the time I'm done with hybridizing or taking photos, I'll end up forgetting to do it and the weeds will slowly take over.
