Weeds are a good indicator of what you can do to improve your soil and your lawn’s health. Even a garden full of dandelions can be radically improved without resorting to chemicals. Try these ideas to help achieve a tolerable balance between lawn and weeds.
- Keep your lawn dense. Open areas, caused by unhealthy weak grass, insect problems, or adverse weather conditions, are an invitation for weeds. Overseed to make it harder for weed seeds to germinate.
- Check the pH of your soil. While many weeds are opportunists and can tolerate a variety of conditions, most grasses find a pH of 7.5 a little high. Check your local garden centre to get a soil testing kit and natural products such as lime to help balance the pH. Many gardeners find that sprinkling and gently raking in compost is a great way to improve the soil. Try leaving grass clippings on the lawn, too.
- Get your mower moving. Mow your grass at approximately 7.5 centimetres (three inches) to keep it healthy. Time the mowing with when your weeds are in flower so you can cut them before they have time to go to seed. If need be, mow more frequently to keep cutting off the tops of the weeds. After a couple of years, you will notice a big improvement. When you do spot the odd dandelion, remember that it’s helpful to beneficial insects, such as butterflies and bees, that need nourishment in the early spring and fall when there are fewer flowers.
- Water wisely. Water deeply and infrequently to strengthen your grass plants, preferably 2.5 centimetres a week, in periods of minimal rain. (You can measure how much you have watered by placing an empty tin can (tuna cans work well) on your lawn before you water.)
- Do a little digging when out for a garden stroll. Hand-digging takes time but it’s very effective because you can remove the root. There are devices made to make the job quicker and easier on your back, such as a Dandelion Digger sold by Lee Valley Tools (www.leevalley.com). If you have a big problem area, enlist the help of some friends or family members for a morning or afternoon.
- Depending on how many weeds you have, applying vinegar to the leaves (with a small brush) may be an effective option. The white vinegar sold in grocery stores is likely a 5 or 10 percent solution. Older, more established plants may require repeated applications or perhaps even higher concentrations of vinegar such as 20 percent. Remember that the strength of the vinegar may harm beneficial insects, so apply directly on the weed leaves with a brush to prevent dispersing into the soil. Visit www.ars.usda.gov/is/pr/2002/020515.htm to find out how researchers dealt with some problem weeds.
- To stop weed seeds from germinating, try an organic pre-emergent, which inhibits the growth of newly sprouting seeds, killing the plant before it becomes a problem. An example of this is corn gluten meal (CGM), which releases a protein whenever it is moistened, inhibiting the growth of plant roots and cutting off supply of water and nutrients. CGM is used mainly for dandelions and crabgrass, as well as curly dock, plantain, lamb’s quarters, pigweed, and knotweed.
- CGM is also used as a fertilizer and (assuming a product is mainly CGM) is an all-natural product that will not burn your lawn.
Where to get it: CGM is also used as livestock feed, so look for it at a farm feed store near you. Some health food stores now also stock it. This product may be more costly than other methods for killing weeds, but it is reputed to be very effective if used correctly, and it has a cumulative effect over time. Meanwhile, you are also providing a natural fertilizer that will help create a lush green lawn.
What kind to buy: There are powdered, granular, and pellet forms of CGM. The powder or granules may be better, as the pellets might be eaten by hungry birds and other critters. The powder, on the other hand, can blow away or get caked up. If you use the powder, water it with a fine mist spray and, if it cakes up, rake it in a bit. Make sure that the product you buy is mainly corn gluten meal, because some products have added nutrients that may enhance the fertilizer effect, but reduce the ability to inhibit weed seeds.
When to apply: Use CGM when seeds are likely to germinate. Do not apply too early because the soil organisms will break it down, rendering it ineffective as weed control, although it will still work as a fertilizer. CGM will work on all seeds so do not apply on a windy day in case it travels to areas where you have seeds that you do want to sprout. Also, don’t apply at the same time that you apply grass seed.
How to apply: Apply five to 10 kilograms to an area of 100 square metres, and more on bare ground because there will be more light and less competition for weeds to thrive. You may find it easier to apply the CGM with a seed or fertilizer spreader. Water it in with a gentle spray to prevent it from scattering and to help work it into the soil. Let it dry but if it is very dry in the days following, you may wish to water it one more time.
Research indicates many weeds can be eliminated in the first year, and the percentage rises with each successive year CGM is used. Store any unused CGM in a dry place, as moisture will break it down.