Even the best maintained and healthiest lawns can get weeds. However an over-abundance of weeds usually reflects grass that is not healthy enough to ward off invaders. No mistake about it. Weeds are hardy and tenacious. They compete with grass for water and nutrients and many times they win the battle.
Weed Control: Weed control products are divided into two groups—those that kill weed seed as it germinates (pre-emergent herbicides) and those that control weeds after they are growing (post-emergent herbicides). The organic pre-emergent is corn gluten meal. The organic post emergent is vinegar.
The natural way to control weeds is to build the soil by increasing the organic matter and most weeds won’t be a problem. In the interim, hand pull problem weeds, spot spray with vinegar-based herbicides and apply corn gluten meal at 20 lbs./1,000 sq. feet spring and fall prior to seed germination.
For winter weeds, spray between Christmas and New Years with vinegar. The best mixture is full strength 10% pickling vinegar into which is mixed 2 oz. orange oil and 1 teaspoon liquid soap per gallon of vinegar. This technique works fairly well any time during the winter when the summer grasses are dormant.
Weeds in Paved Areas??: Weeds can be controlled with non-toxic products. Forget using black plastic, toxic chemical herbicides, salt and bleach. Remember one of our primary rules – do nothing to harm the life in the soil. Bleach and toxic chemical herbicides are poor choices, but there are some good ones.
To keep the weeds out of a decorative or utility gravel area, the best approach is to design them out from the beginning or use organic products later to kill the weeds. Salt, toxic herbicides and bleach should never be used because they contaminate the soil long term. They also leach into the water stream. To head off the problem, install the gravel in a thick layer – 6-8” after scraping away all grasses and weeds.
For additional control, add a layer of white caliche rock before putting the gravel on top. Any weeds that grow through the gravel can be sprayed and killed with a mix of 10% pickling vinegar mixed with 2 ounces orange oil and 1 teaspoon liquid soap or you can use a commercial organic herbicide.
Weeds in Beds: ??Weeds in beds can be killed by removing the tops and then covering the problem area with 1/2″ of compost followed about 5 layers of newspaper. Wet it all down and cover the paper with 2-4″ of shredded mulch. Spot spray any weeds that manage to come through with the vinegar herbicide or commercial organic herbicides.
Vinegar Herbicide Formula:
- 1 gallon of 10% vinegar
- Add 1 ounce orange oil or d-limonene
- 1 teaspoon liquid soap or other surfactant (Bio Wash)
- Add molasses at 1 tablespoon per gallon to the vinegar formula
- Do not add water
Pre-Emergent Weed Control: Pre-emergent herbicides must be in place before the weed seed begins to grow. Annuals, like henbit and annual bluegrass that germinate in the fall as soon as the weather cools. There could be as much as a month or so difference in the arrival of the first significant cold front. For a pre-emergent to be effective for winter weed control in north Texas, it should be applied around September 15 or a month or so later in the southern part of the state.
The same holds for the spring. Many annual weeds, like grassburrs and crabgrass, germinate in the early spring, again depending on temperatures. In northern Texas corn gluten meal should be applied by early March, even earlier farther south. Some years these dates may be too late. Success depends on changes in the weather. Early or late falls and early or late springs make pre-emergent programs difficult. Once in a while the program may fail. Corn gluten meal will fail as a pre-emergent if the soil and weed seed stay moist for a long period after treatment is applied. The constant moisture will override the herbicidal effect, the small roots will start to grow and the fertilizer value of the corn gluten meal will give you very large weeds. Just mow them.
Post-Emergent Weed Control: ?Post emergent control of weeds is done in the organic program primarily with vinegar and vinegar-based products. Spray during warm or hot weather. Straight vinegar (10 or 20%) can be used or vinegar-based products..
Mow a little higher than the organiphobes recommend. Start the season at 1 1/2″ to 2″ and raise to at least 3″ by mid summer. Mow weekly or more often if necessary, leaving the clippings on the lawn. Put occasional excess clippings in the compost pile.
Mowing/Lawn Care: The most important cultural practice associated with maintaining any turfgrass is mowing. When part of the grass plants’ leaf system is removed by mowing, the plant reacts by using high amounts of carbohydrates to replace the leaves that were cut off. Only when the leaves are replaced does root and stem growth renew. The greater amount of leaf surface that is cut off at each mowing, the longer root and stem growth is reduced. Research formed that when no more than 1/3 of the leaf system is removed at one cutting, negative effect on root and stem growth is minimal. The cutting height has an effect on root size. There is a direct relationship between cutting height and the total volume of root system.
Grass clippings should be left on the turf. They do not contribute to thatch so there is no need to “bag” them if a reasonable mowing program is followed.
Edging and Trimming: ?Edging along walks and curbs is needed. Monofilament trimmers can be used along steel edging, curbs, and other hard surfaces but never around trees or shrubs.