Loading... Please wait...

Suppressing Weeds

Posted

Barriers

Weed control barriers are widely available at home improvement stores and nurseries. Installing a barrier in your garden beds will completely remove light from weed seeds, and will literally stand in the way of any sprouts poking up toward the surface. Commercially available weed fabrics and plastics are intended to be semi-permanent to permanent barriers, so they can’t be used in areas where you plan to till or add annuals year after year. They are appropriate for use in established perennial beds or for preventing growth in pathway areas, such as under stepping stones or between raised beds. While these weed barriers are incredibly effective at halting growth for a period of time, they do come with some pretty significant drawbacks. Plastic barriers can prevent rainwater from reaching weeds, but they also keep water from your plants. This problem can be eliminated by using a more pervious fabric barrier. Weed barriers also have a habit of making you frustrated years later when you want to plant in those areas—jamming a spade through that barrier to make a good size hole for transplanted flowers is an exercise in maintaining patience. Finally, you can’t expect to never see a weed again after installing a weed barrier. After covering the barrier with mulch, you will have started the first layer of growing media for future weed seeds. Weeds that can’t grow up from under will just grow on top of your barrier in the future. You really can’t win. Just be sure of what your future plants for any areas you’d like to install barrier in, and expect to have to help it out with a secondary weed control method from time to time.

There are barrier alternatives that address some of the major issues with synthetic store-bought barriers. Many opt to use cardboard and newspapers to create a barrier that will allow water to pass through, and will degrade over time and compost into the soil. This means you aren’t stuck with a barrier in your bed for the next decade, and that if you get tired of it, you won’t have to remove layers upon layers of mulch to get to the barrier to remove it. The downside of this method is that you’ll have to replace it more often than the barriers that don’t decompose.

Of course, you could just mulch. A depth of at least four inches is recommended (five to six is better). And we don’t mean buying bags upon bags of expensive black wood bark mulch necessarily. Much of your yard detritus can be chopped up and used to suppress weeds and add nutrients to your soil. Consider grass clippings, pine needles, dead leaves, compost, and cut up sticks and twigs. This material breaks up faster and dumps great food into the soil for your plants, and if you want, you can cover it in a traditional wood bark for looks.

Herbicide

Contact herbicides are foliar sprays that destroy only the tissue that they touch, making them effective against annual weeds. Perennial weeds will likely withstand damage from contact herbicides since the chemical will not be absorbed by the plant and pulled into the roots, but where root systems don’t need to be destroyed, contact herbicides are fast-working and incredibly effective.

Systemic herbicides can be applied as a foliar spray or a soil treatment, and once applied, will be absorbed into the plant down to the roots. While they don’t work as quickly as contact herbicides, systemic herbicides are much more effective against perennial weeds.

Soil-applied herbicides can be added to the soil prior to tilling and sowing, added after sowing and before crop germination (pre-emergent), and after crop germination and growth (postemergent).

Organic herbicides include vinegar or citrus sprays, applying salt either to the soil or spraying a saltwater mixture directly on the plant. Corn meal gluten is often used as a pre-emergent against crabgrass.

Whether a spray, soil treatment, contact killer, or systemic, be sure to note whether or not the herbicide you’ve chosen is selective or nonselective. This is the key to knowing whether or not your use of this herbicide will affect your other plants. A selective herbicide will target specific weeds without posing a threat to anything around them, but a nonselective herbicide will eliminate the good and bad alike. If using a nonselective herbicide, be aware of how long the active chemical will remain active in the soil to ensure the success of replanting.

Thermal

Sun solarization isn’t for everyone, either because of garden size, length of growing season, and the climate or sun exposure in which you live. For those in hotter, sunnier areas with a long growing season, sun solarization is an organic weed control method that may also double as a pest control method. With a tarp and a brightly lit location, you can harness the heat of the sun to cook unwanted plants and seeds out of the first few inches of your soil. Temperatures under these tarps can reach well over 100 degrees, and after several weeks, anything living under that tarp will be dead, providing you with a clean slate to replant. The problem with this method for those with the sun and heat to try it is that it requires you to leave a significant portion of your garden unused while you are treating it, which isn’t possible for those with small vegetable gardens and limited time to grow. A good idea might be to use this method where edibles aren’t involved, like when reclaiming landscaping space from invasive creepers like ivy or creeping Charlie.

If your weed problem has gotten to a point where things are officially personal, you may want to get somewhat serious in their removal. Flame kills plant tissue in a fraction of a second after contact—plus, it’s really satisfying to set weeds on fire after so many failed attempts at removal. Weed torches and flame guns are about as effective as contact herbicides at killing top growth. Exposure to extreme heat essentially boils the plant’s cells until they burst. For the control of perennial weeds, multiple passes are recommended for control—repeatedly exposing the plant to heat and killing it will burn up the stored energy in the roots quickly as it scrambles to regenerate. While the investment in a weed torch and fuel can be pricey, it is a great organic weed control method for those not wanting to use chemicals, and for those unable to install a barrier or labor over manual weed-pulling. Using a weed flamer eliminates bending and digging and pulling, and makes regular weed control maintenance much more convenient.

Another way you can fry your weeds without chemicals is with boiling water. This might not be something you’d want to do on a large scale, but it’s a good idea if you’re into boiling water in the morning for coffee or tea and always have hot water leftover. Simply boil an amount of water in a pot or kettle, locate some weeds, and carefully pour the water over the top of the weed. Like with the flame method, you’ll need to do this repeatedly to kill perennial weeds by exhausting their energy supply, but it will work. Just be careful with weeds in and around beds or plants that you’d like to keep. Pouring boiling water into the soil will cull some beneficial microbes and harm the roots of nearby keepers as it spreads. This is a great way to keep those annoying leafy weeds out of the cracks in brick or stone patios, especially if your kitchen is nearby.

Crop Rotation and Cover Cropping

here are a lot of reasons to use cover crops and rotation when planting, especially large gardens and crops. Crop rotation has long been used to maintain the level of nutrients in the soil, and cover crops are essential in erosion control and the prevention of nutrient pollution in water. Another beneficial aspect of these techniques is weed control.

Cover cropping allows you to grow your own sustainable mulch that could possibly have a positive impact on the yields of your garden. While cover crops are growing in between plantings, they rob weeds of real estate in your beds, and when the time comes to plant your garden, they can be mowed before they reseed themselves and used as a pretty effective mulch for weed suppression. The top growth can be used as a mulch during the growing season, and the roots below, if undisturbed, will work to crowd weeds out, prevent erosion, and will help with moisture retention throughout the season. Some researchers even believe that certain cover crops actually improve the yield and overall vigor of your vegetables.

Weeds are tricky, especially in gardens that are planted and replanted every year. Through the years, certain weeds have actually adapted to the way we farm. We till the soil, seed a crop, allow it to grow, harvest, till the soil, seed the crop again, grow, harvest, till, seed, grow, harvest, over and over again. These nasty little invaders have actually come to depend on this pattern of tilling, sowing, and tilling to spread their seed and provide them with the specific nutrients that certain plants provide when cropped continuously. Totally rude, right? However, what these weeds can’t adapt to so well is a disruption in this continuous cropping cycle. Crop rotation can create wildly different growth environments for weeds, removing or adding light, moisture, nutrients, and causing soil disturbances that prevent them from taking root. For example, planting a tall leafy crop after planting a short crop steals light from full sun weeds that moved in and dropped seed last season, and rotating between crops that need to be sowed at various times means that light-germinating weed seeds that may be tilled up during planting may be suppressed due to exposure to unfavorable conditions. While there is always a weed that will be able to thrive in the conditions you’ve created, constantly altering features of your planting area that individual weeds can exploit will prove challenging to their proliferation in the long term.

Manual Removal

There’s a reason we’ve saved it for last, but sadly, it is still the most effective and fastest way to rid yourself of a garden eyesore. Where weeds are tall or substantial or where they have a long aggressive taproot, your best bet is pulling it out by hand. If you’re still doing this only with a spade and gloves, you can definitely make it easier on yourself by taking advantage of the many standing and sitting weeding tools on the market that do take away a lot of the struggle.

Weeding hand tools come in every shape that even exists, with many of them designed for the removal of a specific pest or for use in specific situations, such as between pavers. One basic weeding tool shape is a straight metal rod with two prongs on the end. These are typically marketed as being for dandelion removal since the prongs at the end of the tool are great for getting under long taproots, but they work well for getting between pavers and bricks to pull out weeds. The hand tool probably most recommended by gardeners is the Hori Hori weeding knife, a good size knife that usually features at least one serrated side. This knife is really an all-purpose garden tool, great for trimming, digging, cutting, and most importantly, getting up under the roots of weeds in the ground and slicing the weed out of the soil. Some of the more unique tools you can use without getting on your hands and knees. Weeding brushes look like little brooms with rigid wire bristles. They are used for getting dirt, moss, weeds, and much out of the grout or in between bricks on the patio by vigorously scraping and sweeping between them. There are a variety of auger or corkscrew-like tools that you can insert into the ground over an offending weed, twist, and then pull to remove.