Got this information from another group via email, so don’t know what the source of this information is:
Organic Landscaping in Planting Beds
“Weed control without chemicals” may conjure up unpleasant thoughts of getting down on your hands and knees in the yard on a hot day and pulling out stubborn weeds by hand. But weed control without chemicals needn’t be so primitive, so mindless. In the resources to which I provide links below, I discuss a variety of weed-control components to be used in planting beds. They should be used in conjunction with each other. Weed control without chemicals can be tough work, and I want you to work smarter, not harder. No need to revert to the Stone Age!
Weed Control Without Chemicals: Laying the Foundation
The first smart idea in a project of weed control without chemicals is to prepare the plot of ground in question. Just as in a construction project, laying a good foundation is of the utmost importance. In this context, by foundation” I mean the state of the ground where your plants will be growing. Implement these ideas before you plant, so that you’ll get off to a smooth start in your project of weed control without chemicals.
1. Killing Weeds Through Soil Solarization
Soil solarization is a preventive, organic method of killing weeds — before they even sprout! The advice below is meant for homeowners wishing to start out with a clean slate, re-landscaping a weed-filled patch of land in such a way as to reduce to a minimum the hassle of weed control in the future.
2. How to Lay Landscape Fabrics
For those in need of soil solarization (see above), installing landscape fabrics can be considered Step #2 in the project of weed control without chemicals. For those with less weedy properties, it’s Step #1. I promised you above that weed control without chemicals wouldn’t mean going back to the Stone Age, and landscape fabrics are a case in point. Landscape fabrics are a hi-tech ally in the battle against weeds.
3. Using Garden Mulch
As the final element in a good “foundation” for your bed of annuals, perennials or shrubs, you should apply garden mulch on top of the landscape fabric. Many skip right to mulching in the project of weed control without chemicals, but I do advise you to lay the landscape fabric first: it will lengthen the life of your garden mulch.
Q&A on Mulching Gardens
Weed Control Without Chemicals: Pre-Emergent and Post-Emergent Organic Herbicides
“Pre-emergent herbicides” is a fancy way of referring to herbicides that attack annual weedy plants at the source: their seeds. That is, they act to inhibit seed germination before the plants in question even have a chance to announce themselves to the world above! Corn gluten is a pre-emergent herbicide used for weed control without chemicals. Remember, corn gluten will inhibit the seed of “good” plants from germinating, too, so don’t use it in planting beds where you’re starting plants from seed.
By contrast, you apply “post-emergent herbicides” only after the antagonists have appeared on stage. For weed control without chemicals, try vinegar as a weed killer. Even plain old household vinegar is effective if you have only young weeds to deal with in your planting bed. It’s the acetic acid in vinegar that gives it its herbicidal abilities. The higher the percentage of acetic acid in the vinegar, the better. Vinegar used for culinary purposes is relatively low (5%) in acetic acid, but you can boil it down to increase its strength — a provision that is necessary
if you’ll be applying it on full-grown weeds. Alternatively, you can try to buy the super-strength vinegar in stores that cater to the agricultural community.
A word of warning, though, when using vinegar as an herbicide: apply it directly onto the weeds, since vinegar is a non-selective herbicide and will harm plants that are inadvertently exposed to it. For this reason, vinegar isn’t especially effective for battling lawn weeds: you’d almost inevitably end up with too much collateral damage to your grass. But vinegar is a fine organic alternative in planting beds, as long as you watch where you’re spraying!
Weed Control Without Chemicals: In Case You Still End Up Pulling Weeds
With landscape fabric and garden mulch in place, the bad news is that, even then, you may still get weeds. But the good news is that those weeds will be very easy to pull out. Pulling weeds embedded in mulch is not nearly as difficult as pulling weeds embedded in soil. Thus with a good “foundation,” you may not even feel the need to bother with the corn gluten and vinegar: 5 minutes of easy pulling here and there should get the job done.
One exception to this may arise: if the integrity of the landscape fabric has been compromised, weeds may strike down roots in the soil beneath, making them difficult to pull out. In this case, water the area in question beforehand. It’s usually easier to extricate weeds from moist soil than from dry soil.