There is this thing called a lawnmower. You probably already have one. It's job is to cut things down close to the ground. Since it is so effective at killing plants that can't handle continous cutting, it doesn't really seem to be recognized as one of the best machines ever invented for controlling unwanted plants. It will get rid of the loosestrife. It will also significantly control the mint, though it is much better at growing under the cutting blades. Any plant that either cannot handle continuous cutting, or cannot grow close to the ground can easily be controlled with the mower. This covers almost all of the truly bad plants. Compared to poison ivy, rosa multiflora, bush honeysuckle and phragmites, dandelions are not a concern.

OK, let me get this correctly. You mulched heavily, sprayed anything that remained, then put Preen on top. Since the green things you sprayed were probably flowers and the mulch can keep plants from coming up? Any of the flowers that put out seed will have their seed prevented from coming up. Where do you think the flowers are going to pop up from? From what was written sounds to me very few if anything will come up. Better to have given the advice to get a book on weeds and/or a book on garden plants so that the original poster can find out which plants are which. Unless you have clearly defined marked plants it would be better to wait until your plants start growing before adding the mulch etc. Pulling a few weeds will prevent the heartbreak of finding out that you pulled the plants you were expecting and left the weeds. It sounds funny but even experienced gardeners will destroy things that had been on their wishlists because they don't recognize them. Tulips and some of the iris's may be emerging. Start doing a patrol to see the new things that are emerging. If you don't know what they are introduce yourself to a neighbor to see if they know. Hosta's will be later and depending on the type of lily they could emerge any time from now until July. Not all things come up at once. Enjoy your new place, try to keep the weeds down once you find out which is which. If you are lucky the previous owners will have planted some of the spring flowers such as Jack n Pulpit that come up then disappear when it gets warmer.

I had a lawn-wide infestation of nut sedge after replanting the lawn. You cannot kill nut sedge in one year, it is an ongoing project. I have used Sedge Hammer and it has been quite effective. I have two small spots of sedge (about 10 plants in total) left in the lawn. You have to apply Sedge Hammer repeatedly (I do it about every two weeks) until the sedge leaves turn brown, and the plant dies. The problem with nut sedge is that even if you kill the leaves, the herbicide only trans-locates back about 2-3 nuts in the root chain. The roots can have up to seven nuts on any root. That is the problem - there will be nuts left to germinate the next year. That's why it will come back the next year, there will still be nuts in the root mass that are still active. So, what you are doing the next year, is killing the left over nuts, and 2-3 nuts back from them. Ultimately, you will kill all of the nuts and the plant will disappear. The problem with trying to dig the plant out is that the roots are very fine and fragile. No matter how careful you are, you will end up leaving some of the nuts in the ground, and as soon as the main plant has been taken out, the remaining nuts will start to germinate. Roundup (glyphosate) will do nothing to the plant. You need to use a sedge-specific herbicide like Sedge Hammer with spreader sticker in the mix. I have found that a small amount of Quicksilver herbicide added to the Sedge Hammer seems to increase the effectiveness. I apply the Sedge Hammer / Quicksilver / spreader sticker mixture after the plants have at least three to five leaves and the temperature is above 80 degrees. It usually takes two treatments over two weeks to kill the plant for this year. I then monitor the area the next year and repeat the treatment. Eventually, you can kill all of the sedge because there will be no more nuts left in the ground to germinate. In my case, it has taken about six years to get all of the nut sedge out a 3000+ square foot lawn. But, since you only need to treat the plant 2-3 times over four week period, it is really not very work intensive. Once you treat the plant for the year - you're done until the next year. It's a war of attrition and you just have to work at it until it's all gone. It can be done, I've done it in my lawn.

In my case, it's a spray (I use a hose end but my hand is very steady and I'm used to doing this). So I simply go over the gardens just like I would the lawn, applying evenly. Almost everything in the gardens was added as an adolescent plant, already sprouted indoors from February through early April, so the pre-emergent doesn't do anything to them. The few natural re-seeders are either unaffected by the Prodiamine, or the number of seeds is so high that it simply doesn't matter. A few that I wish were deterred aren't bothered in the slightest (last year's cleome seeds, I'm looking at you here). Back when I used Dimension granular, I put on a glove and hand-scattered it. It worked about the same, and didn't do any damage.