Controlling Weeds Organically
You may already know that weeds are a challenge to manage as a part of an organic program. As with many of our clients, we also strive to create perfect lawns of our own – lawns that are visually appealing and weed-free. However, nature calls for and thrives through bio-diversity. Biodiversity, although a naturally beneficial state, works against a solid green lawn that is a monoculture. So how does the organically-minded grower deal with weeds? The answer begins with a better understanding of the role of weeds.
How Weeds Help
What is a weed, really? A weed is just a plant out of place. While many of us see weeds as detrimental to a beautiful lawn, weeds do serve a natural purpose.
The natural role of weeds is to build soil fertility. How you ask? Every weed has a specific soil type requirement as well as mineral deficiencies or excesses under which it thrives. In this way, each weed draws out nutrients from the soil that many other plants might not be able to easily access. This may be through a deeper taproot, a more fibrous root system or some other symbiotic relationship with soil microorganisms.
Weeds can also be a great indicator to help identify specific soil problems. If there are one or two weeds that seem to proliferate in an area of a lawn, we may take that as a sign of compaction, deficiencies or some other soil related problem that needs to be addressed. For example, a lawn that has a bad problem with dandelions often means calcium is unavailable, or that the soil is not biologically active. This is not uncommon in North Texas soils, which normally are high in calcium but are often biologically inactive. Therefore, the answer is not to add more calcium but to add compost or compost tea extract to stimulate microbial activity. By introducing life back into the soil we create a living breathing soil that allows nutrients to be more available.
Reconciling Nature with a Weed-Free Lawn
You an achieve a green Lawn with fewer weeds, naturally. It is often taught that a healthy lawn will have fewer weeds. This is a true statement, but does not necessarily mean you’ll have a 100% weed-free lawn. Many times we start off at Soils Alive with a lawn that might be 50% weeds and within a year the lawn is much healthier and we can reduce the weeds down to 10%. Although, this can be a dramatic reduction in the number of weeds, organic treatment alone is not enough to achieve the uniformity of a desired monoculture. Therefore, it is still necessary to hand pull weeds or treat for them as they emerge.
Different Lawn Grasses Suppress Weeds Differently
St. Augustine: We’ve found that St. Augustine to be the best weed suppressing lawn grass. St. Augustine has a wide leaf-blade that does a better job of shading and out-competing most weeds.
Bermuda: Bermuda, on the other hand, while thick and dense, just doesn’t compete well enough to keep most weeds out. Once crab grass gets started in Bermuda it will out-compete the lawn.
Zoysia: When allowed to grow taller, by mowing less often, Zoysia creates a very thick mat that keeps most weeds out once established from solid sod. If Zoysia becomes stressed or gets damaged it does not grow fast enough to fill in, and those areas can easily become weedy.
Other Mixtures: Over-seeding Bermuda with rye or fescue grass is a good way of controlling winter weeds. If winter weeds do germinate in winter rye grass the competition and mowing does not allow them to become a major problem. One “weed” that we hear a lot of complaints about is fescue. Fescue that is put down as an over-seeding solution can often remain green well into summer, long after your warm season grasses have re-emerged. Sometimes it will persist until the following spring and can create the look of weeds in the lawn, even though it was intentionally seeded. There is no organic way to remove this left-over fescue other than to dig it out.
Prevent Weeds Through Organic Treatments
Using corn gluten meal as a pre-emergent and organic herbicides for post-emergent control can help keep many weeds from becoming a big problem in your lawn. Remember though, that with both of these control methods, how and when you apply them is critical. Knowing when or what conditions initiate weed germination allows one to time the corn gluten meal application to best suppress seed germination. Also, you must not disturb the corn gluten meal once it’s applied in order for it to be effective. Organic post-emergent control products are best used just after germination, when weeds are small and easily controlled. Many weeds will germinate continuously over an extended period; this can often catch some organic gardeners by surprise when it appears a product did not work as expected. In reality, the product may have needed to be re-applied in order to work properly.
One final piece of advice when using organic weed treatments: Identify the weeds you are treating before you treat them. Knowing what you’re treating and when best to treat for it will make your efforts more effective. Also, always thoroughly read the label of any product you use before you apply it.
Remember, weeds serve a purpose. We as organic gardeners need to accept them as one of Mother Nature’s tools. Understanding and accepting the natural role of weeds can help all of us make more informed and responsible decisions about how to deal with them, thus creating a more beautiful and naturally healthy lawn and landscape.