Weed Control

Most weed killers are designed to kill broad leafed weeds. Trees are broad leafed. Weed killer can stunt the growth and even kill an otherwise healthy tree. The label will never tell you this directly. Even weed-and-feed fertilizers can and will cause damage to trees. A deciduous tree has roots that are about 3 times as far reaching as the tree is tall. Many people say they do not spray around the tree but that doesn’t mean the tree does not find the poison. 2-4-D is the bad ingredient in lawn weed control products. Pre-emergent products stop the emergence of seeds, not weeds. These do not harm plants, trees, or weeds. They only affect seeds. These are good products to use in areas where you are not seeding.


The following Overview & Benefits comes from a 3 – 6 month products. These usually kill all trees and shrubs with a broad leaf. Usually needled trees (pine) and shrubs (juniper) are not affected but there are many different brand names and obviously have not researched everyone.

Overview & Benefits

  • Kills existing weeds and prevents new ones from growing for up to 4 months!
  • Rainproof in 10 minutes.
  • Visible results in 3 hours.
  • Kills the root – guaranteed!


  • It says it prevents weeds for a year. This means it sterilizes the ground for at least that long. NOTHING can grow there. These are poisonous to EVERYTHING, broad leafed and needled trees and shrubs.
  • It says it is rainproof after 30 minutes, this means that no matter how much water or it rains, the poison will remain in the ground continually poisoning. You cannot wash it out! In fact, the more you water, the more live things have the opportunity to drink more poison. If you spray on a hill, when it rains, the poisoned water can flow down and kill everything in the runoff line.
  • You may not see visible signs of poisoning on a tree within 12 hours. In fact, it could take until the next growing season to see results. Either way, it is not reversible.
  • It says it is for use on driveways, patios, sidewalks, and gravel areas however, these products should never be used around a home where people and things live. If the space is big enough in your patio or sidewalk for a weed to grow up, you can bet there is a tree root waiting there for water. If the water it gets is poisoned, it will get sick and the growth will be stunted. If it gets enough poison, it will die, or at least partially die. In fact, the company has staked its reputation on it when it says … …
  • Kills roots – guaranteed!

Weed & Feed products kill slowly. In fact, often the damage is undetectable for years. But the continuous poisoning weakens trees, leaving them unable to defend themselves from normal stressors. These trees can succumb to infestation or disease or simply die during a drought or other stress events. If you use anything combined with your lawn fertilizer, pre-emergent is not harmful to trees – that is fertilizers with pre-emergent rather than fertilizers with weed control products.


The following Overview & Benefits comes from a glyphosate product.

Overview & Benefits

  • Kills existing weeds and grasses to the root – guaranteed!
  • Ideal for targeting weeds in garden and landscaped beds. Can also be used on driveways, sidewalks and patios.
  • Visible results in 3 hours. Rainproof in 10 minutes.

These products have glyphosate as a primary ingredient. On its own it does not sterilize the ground. In fact, it kills the weed from the top down rather than poisoning the soil and killing from the root up. It serves as a sun block, preventing photosynthesis, thus killing the weed. Glyphosate is the active ingredient that does not kill trees unless sprayed directly on the leaves. Be aware that many very bad weed killers have a percentage of glyphosate but have other harmful ingredients. Just because it has glyphosate does not mean it is not harmful to trees.

Pre-emergent does not harm anything green. It does not kill weeds. It stops the germination of seeds. Since most weeds come from seeds, this product prevents weeds. It also prevents seeds from germinating in your grass or flower beds so if you are seeding, this product will not help your cause. If you use any product on your grass along with your fertilizers, pre-emergent is okay to use.