How can I kill weeds and grass in flower beds and around trees?

So as to not kill your trees or flowers, all you can do is hand pull. It sucks I know.

Hi Mr. Will,

I used a combination of hand pulling and vinegar with a few drops of Dawn in my garden this year. You just have to be careful not to get vinegar on your plants that you want to keep. My garden had a lot of "dirt" areas that were just growing weeds. Those are the places where I used the vinegar. I was also very careful to just spray directly on the weeds. Wishing you the best.

The BEST killer I know is paper several layers or cardboard over lapping. You can cut a hole for each flower to plant. Cover it all with mulch.

I'm not sure there is anything you can use over a large area like lawn that will not hurt the tree underneath. You can rent a turf cutter that will cut away the lawn. The other option is to cover the entire lawn with a tarp, cardboard, or boards to kill the lawn that way.

Weed management can be a multifaceted approach.

Some recommendations include the following

I have resorted to placing pieces of cardboard out on top of weeds or unwanted groundcover-in the flower garden— on top of weeds but not covering flowers and placing mulch on top. It works very well for smothering out unwanted vegetation in that area as well as around trees.

Management

Cultural control in ornamental beds

Prevent going to seed; hand pulls easily.

Do not compost plants with seed heads.

In Lawns

• Cultural Practices
• Maintain healthy, dense turf that can compete and prevent weed establishment.
• Mechanical Management
• Hand pulling or using an appropriate weeding tool are the primary means of mechanical weed control in lawns. This is a viable option at the beginning of an infestation and on young weeds. Hand pulling when the soil is moist makes the task easier. Weeds with tap roots like dandelions or have a basal rosette (leaves clustered close to the ground) like plantain are easier to pull than weeds such as Bermudagrass (wiregrass) or creeping Charlie (ground ivy) that spread with stolons or creeping stems that root along the ground.

• Chemical Prevention/Treatment in Lawns
• Herbicides should be used as a last resort because of the potential risks to people, animals, and the environment. Be aware of these precautions first.
• Use a granular (apply with a spreader), selective, preemergent herbicide. Apply a preemergent without nitrogen fertilizer. Look for the active ingredient: Prodiamine (Barricade) or other preemergents labeled for crabgrass control. Apply in early spring (March) before it germinates. It germinates earlier than crabgrass so to prevent J. stiltgrass the preemergent needs to be applied a couple of weeks earlier than for crabgrass prevention.
• Rainfall or irrigation is required to dissolve the herbicide which is then absorbed into the upper portion of the soil and forms a barrier which kills weed seedlings. Preemergent grass herbicides have residual activity that lasts for several weeks after application. High temperatures and rainfall will decrease the length of time they remain at sufficient concentration to be effective.
• 
  
• Tips for application:
If planning soil disturbance, such as aeration, do it before application.Apply prior to seed germination which begins, in early spring a couple of weeks before crabgrass seeds germinate.Water after application, according to label.A second application may be possible, usually 6-8 weeks later (see product label).Consult label for specific waiting period between application and overseeding.

I would add 'patience'. Weeds are weeds because they are tough and can grow anywhere.

When mulch does not work, try spraying plain water on the weeds when under direct sunlight, to burn the leaves.

That does sound cruel, doesn't it?