Weed Control and Horticulture Tips For Home Lawns and Gardens

When using any type of pesticide it is important to read and follow the instructions on the label. All chemicals are different and their compositions make them unique in their effects on plants versus humans. Just because a chemical is not highly toxic to a broad variety of plants does not mean that it is not highly toxic to human, and vice versa. Respect all of them.

Weeds can be characterized as selected vegetation that is undesired within other vegetation that is selectively desired. (The operative term here is selectively desired.)

Fortunately there are chemical herbicides (weed killers) that are selective in the types of weeds that they kill or affect.

In general, there are four types of selective Herbicides:

Grass Killers

Grass Killers kill grasses without harming most of the surrounding foliage with leaves on them. These types of chemicals can be used directly over plants and planter beds to kill unwanted grasses in the planter bed. Fortunately, this chemical works well on Bermuda Grass as well. Read the label carefully to determine which plants it can be used on. If you have a leaf plant that is not listed on the label it is likely because it has not been tested on that leafy species. We recommend testing it over one plant before applying it over many of the same that you have in your garden.

There are two commercially available Grass Killing Herbicides that we recommend: Fuslaid and Post. Both are spray on chemicals that you mix with water and apply to grass weeds that are growing in ornamental planter beds. Follow the application directions and rates carefully. Typically they take about two weeks from the time of application to take effect.

Broad Leaf Killers

Broad Leaf Killers are more or less the opposite of Grass Killers. They can be applied directly over most lawns and will selectively kill the broad leafs without harm to the lawn. These chemicals are very volatile and, while relatively safe for humans, drift will severely damage adjacent plantings. Spray on low wind days with low pressure to reduce spray drift.

Weed B Gone is a very effective broad leaf killer that is available on the retail market. A newer product, Turflon, is a broad leaf killer that is not registered for use on Bermuda or St. Augustine because it will severely damage or kill those species of grasses. Turflon is not labeled as a Bermuda Grass killer, but is commonly used to control Bermuda Grass within fine turf grass lawns. Turflon should be used on Blue, Rye and Fescue grasses.

Both Weed B Gone and Turflon are spray on chemicals that you mix with water and apply to lawns in order to kill weeds. Follow the application directions and rates carefully including ambient temperature restrictions.

As mentioned above, Broad Leaf herbicides are very strong and should not be used on shrubs or leafy ground covers that you wish to keep.

Broad Spectrums Non-Selective Herbicides

Both types of herbicides mentioned above are selective in what they will have an effect on. They are specific in that they kill either grass or broad leafed plants.

Non-Selective Herbicides are self explanatory in that they are not selective in what they kill. They generally damage or kill virtually any plant material they contact. Round-Up falls into this category.

Round-Up is a non-selective broad spectrum herbicide that is intended to kill all herbaceous plants that it touches. It is especially helpful for sidewalk cracks and areas with no desired plantings.

Seed Killers

The fourth type of selective herbicide is a Pre Emerchant Herbicide (also known as a seed killer) that will kill seeds but should not harm existing plants or lawns (depending on the label).

Ronstar is a granular product that will not harm most common plants, nor is it harmful to Blue, Rye or Fescue Grasses. Ronstar is available in 40 or 50 pound bags for about $60.00. This product is best applied with a Whirlybird spreader at the approximate rate of four pounds per 1000 square feet, and is effective for about three to four months.

Upon application of any of the weed killers referenced above, it would be prudent to apply this product to minimize reproduction of weeds via seeds that may be left behind or that blow in from neighbors. At such time that your weed population is under control, it would be advisable to regularly treat with Ronstar Pre Emerchant (seed killer) as necessary for prevention. Once the weed problem is under control, you can cut back the use of Ronstar to an as needed basis. It is recommended to use Ronstar Pre Emerchant during rainy seasons as well to control new season seeds that tend to emerge.

Ronstar Pre Emergent is not recommended for use on perennials and annuals, as it will severely damage the plants. Spot treating with the other weed killers will be helpful (and necessary) from time to time. As always, be sure to read the label as some Pre Emerchant herbicides may harm some plantings, especially herbatious type plants such as annuals.

If your lawn is dense and has become resistant to weed population, and you’re at the point where you can easily control the lawn weeds with spot treatment, then avoid the repetitive applications of Ronstar Pre Emerchant seed killers as it does have nominal negative impact on the vitality and maturing of a fine lawn. Also, it will save you costs.

The Importance of Safe Chemical Application

As discussed in the opening paragraph, the selective chemicals can potentially be as or more dangerous to humans than they are to foliage. All the products mentioned above are intended to be used in accord with the label and must be respected.

Chemical labels typically have the signal words like: “CAUTION” “WARNING” or “DANGER!” These indicate the relative hazard of the products.

When a label says “CAUTION” it means it is the least hazardous to humans, while “DANGER” is the most hazardous to humans. This is true for all chemical products including those around the household.

Whenever applying any of these chemicals, especially for the first time, you should protect yourself against the concentrate and the mixed product. While these products are safer in their diluted rates after mixing with water and also after drying in the garden, do not underestimate the safety required to apply and handle these commercial chemicals.

Because these chemicals are concentrated and at their strongest prior to mixing with water, be sure to put on goggles, rubber gloves, and long sleeves before opening or handling any open containers or bags. A dust mask and rubber boots are suggested but not usually necessary. Read the label in advance as it will dictate the precautions!

Along with the specified safety equipment, the equipment required to apply the granular herbicide and the fertilizer would be a broadcast spreader such as a Whirlybird. The liquid chemicals would be best applied through one or two gallon pump sprayers. It is recommended to have different sprayers for the different chemicals. Since spot spraying may be necessary from time to time, it may be useful to label the sprayers with a felt pen and store unused diluted portions for subsequent use within the containers. Do not rinse containers into storm drains or sewers

Also, you can purchase colorants to add to the chemical solutions so that you can easily see the area and amounts that have been sprayed. The spray colorants are inexpensive and dissipate in the sunlight within a few days.

Chemical Absorption

Chemicals are absorbed by the plants in several different ways. Most applications are for contact application. Meaning the chemical must come in contact with the foliage or with some insecticides with the insect itself to be effective. A few chemicals are absorbed through root absorbsion and are usually applied as a soil drench or root feeder.

There are such things as bark injections, however this is not recommended for someone who is new to this process. The other solutions mentioned above are easier and typically just as effective.


Translocation is a term that implies the chemical is absorbed into the plant and flows through and with the plant fluids.

Pesticide translocation refers to the plant absorbing the chemical into the tissue and fluids of the plant. Translocating pesticides are preferred as they affect the entire plant from roots to leaf.

A translocating herbicide will translocate to kill beyond what it contacts; it will also kill the roots.

A translocating insecticide will actually make the plant poisonous to the target insect. As the insect preys on the plant it will ingest the insecticide that has translocated through the plant.

The Best Ammunition Against Pests

A thriving, healthy plant will ward off pest invitation (weeds, insects or fungus) by its own competitive nature better than any use of synthetics.

Most ornamental plants and grasses that are used are not indigenous to this region; however, with regimented feedings and watering they will perform admirably. The plants have natural defenses that work well within their indigenous area. Keeping your plants and gardens healthy is your absolute best defense against unwanted pests.


When planting shrubs or trees it is prudent to dig the plant pit to about twice the diameter and twice the depth as the root ball. Use about one third organic amendment and an ounce of fertilizer blended with the native excavated plant pit soil. The most critical issue for new plantings is to plant in a manner to insure that after it has settled, the top of the root ball is one to two inches above the adjacent soil grade. While you definitely do not want soil to cover the top of the root ball it is very advantageous to apply two to four inches of organic mulch over the root ball.


It is strongly advised to apply a balanced fertilizer to all turf and ground cover at a rate of about five pounds per thousand square feet; and about one ounce to all shrubs and trees once every other month or six times per year. A balanced fertilizer is a granular product with NPK (Nitrogen, Phosphorus, Potassium) of about 15-15-15 with minor nutrient elements included.

Note: If your fertilization has iron in it, do not let it sit on the concrete as it will stain and leave rust spots.


Water is even more critical than food for life, which is why it is highly recommended to get a timer controlled sprinkling system. Most people cannot accurately distribute the correct amounts of water on the correct watering days per week to optimize the plant vitality. Automatic irrigation is the most cost effective aspect of a fine lawn and garden.


While the previously mentioned strategies of plant vitality are generally the best ammunition to fight off pest and predators of the garden, there is a relatively new insecticide, called Merit, which has some extraordinary characteristics.

Merit is within the lowest toxicity category for pesticide chemicals. This means that it is not among the more dangerous pesticides to use. However, it still produces very good results on controlling a wide variety of insects in a garden. It will work as a contact killer and will also work as a translocating chemical.

A contact insect killer, as the name implies will kill only if it contacts the pest directly. The translocating aspect of the chemical means that the plants will absorb the chemical and will then have the plant fluids become toxic to the insects that are feeding on the plants. Merit solutions can be either sprayed onto the plant foliage to be absorbed by the plant or the solution can be applied as a root feeding to be taken up by the plants.

While this chemical is indeed a broad spectrum insecticide, there are certain pests that it may be ineffective on. Currently the label does not indicate control of many of the insect pests that penetrate and feed inside of the bark of plants or trees. This is contrary to what one might expect as the Translocating aspects of this chemical would seem to effect the fluids that boring insects are exposed to. Furthermore, while using this product to fight labeled pests we have seen a decline in the population of certain boring insects that were not labeled. While using this chemical we have seen no adverse effect to plant material. Please read the entire label and follow directions. Please remember that more is not always better.

Disclaimer: These tips are intended to be informative in a general sense but in no way are to be construed as a recommendation for use of any pesticide or product. Recommendations are general and will vary for each unique landscape.

Return to Sprinkler Times Landscaping Tips