There are many ways to suppress weeds in a garden or flowerbed.Chemicals are not always the best answer.
Smothering has been the standard for years. Mulch or a covering material is very common. I use my grass clippings around my vegetable plants and it will decompose in one season so that it feeds the plant as it protects the nutrient's from weed roots. Leafs are another popular free mulching material. They will break down faster and hold fewer bugs if they are mowed with a lawn mower into smaller pieces before application. I have also used sheet metal, solid plastic sheets and boards to stop growth. The metal will get hot in the full sun and burn whatever is under it. The plastics should be opaque so they do not form a tiny greenhouse effect and aid weed growth. The boards double as a slug-hiding place. Turn them once per week and cut the slugs with your garden knife.
I own four sprayers. One is a two-gallon that I inherited from my father. I bought another two-gallon and own two one-gallon sprayers. This allows me to keep the chemicals in different sprayers to avoid contamination from a cross chemical. I also mark each container with the chemical that is currently inside of the sprayer. I have cardboard tags, covered in PVC, and wires attached for easy name changes. This becomes critical as I go from total kill chemicals to basic weed killers. I spot spray the problem plants instead of sweeping the entire area. This saves on cost and the amount of chemicals in a given treatment area.
Next on my list of dreaded weeds is the wild violet. The plants forms rhizomes and are difficult to control. Persistence pays off when dealing with these weeds. Weed stop claims to control it but I have yet to be impressed. They make a special concentrate for the wild violets and that is my choice of products. They require persistence and repeat treatment if you have a wide spread problem. Small patches are best dealt with by digging the entire root system and disposing of it properly.
The next problem child that I will address is Nut Sedge. This fast growing weed is an eye sore that will outgrow every plant in your yard. It is known as water grass to many people because it seems to grow 5” the day following a rainfall. Digging will control this weed but it requires the same persistence as the wild violet due to its rhizomes. Control can be obtained by using Glyphosate (Round up or equal) very carefully sprayed on just that plant. Sedge Hammer is also a good product and Weed Stop seems to have a very positive effect in controlling this weed.
I caution all vegetable gardeners to not use any chemicals in your gardening beds. It is one thing to use chemicals to control weeds in a lawn, or a flowerbed, but never use chemicals near plants that grow fruit or vegetables for consumption. These areas should be hoed, dug, raked or preferably mulched with organic matter, which will suffocate the weeds, while building the soil as it decomposes.
Poisson Ivy and all other Ivies require special chemicals to control. The Ortho MAX Concentrate Poison Ivy and Tough-Brush Killer is designed to kill over 60 types of tough brush and weeds including poison ivy, kudzu, poison oak, stumps and blackberries. The formula penetrates through to the roots to destroy weeds systemically. Provides rainproof control in as little as 2 hours after application and is my choice for this type of tough weed control.
The basic rule of thumb is to dig weeds out if possible before resorting to chemicals. If you need chemicals due to the nature of the infestation then do your best to spot spray the problem plants. This limits the amount of poison applied to your problem areas.
I do not support particular brands. They are all pretty much equal. Read the label for suggested applications and use some common sense.