We used to have a partner company that provided organic maintenance service to residential and commercial customers. Every single prospective customer asked the question “what do you do about weeds”.
Two methods exist to control weeds: prevent them or kill them – prevention is obviously the preferred strategy.
- Prevent weed seed germination – corn gluten meal has proven to prevent seed germination in a number of studies and I can attest to its effectiveness. It is not a guarantee and does not work on all weeds. There is a small window of time that it may be applied (varies with your location) to be effective – get it down just before weed seeds are germinating. Regular use over consecutive seasons will continually reduce the number of weeds. At a cost of about $1/pound and an application rate of about 20 lbs/1,000 square feet, it is not an inexpensive solution. Corn gluten can be found at many feed stores. One other note – corn gluten will also prevent the germination of desirable plant seeds.
- Block the sun – weeds require sunlight just like your desirable plants. In your lawn, block the sun that the weeds require by maintaining a thick turf (over-seed regularly) and cutting the grass long (3.5″). In your landscape, cover up bare spots with 3″ of mulch.
- No bare spots – weed seeds blow across your property every day looking for a home. Don’t give them one by keeping bare soil covered: seed bare spots, cover spots with mulch, use ground cover.
- Do not till soil – you have many weed seeds lying dormant in your soil where they have been for years. When you turn your soil you are bringing these to the surface where they will flourish. Turning soil also destroys beneficial biology.
- Use landscape fabric – when you are installing or re-doing landscape areas, place fabric over the top of your soil (after removing existing weeds) and cover with mulch. Weeds may re-develop in your mulch over time but they will not be able to root deeply and can easily be removed.
- Pull the weeds – not something we want to hear. We have been maintaining our personal property organically for 6 years and still get weeds, but not many. Our regular ‘weed hunt’ takes about 10 minutes a week – when we see a weed, we dig it out. Taking care of the problem before it gets out of hand is the secret.
- Boiling water – pouring boiling water on weeds is effective; some weeds will die and some of your desirable plants may die as well. I have found that pulling a weed is much quicker, more likely to work and less likely to damage surrounding plants.
- Vinegar – many folks suggest a vinegar/soap mix (soap helps the vinegar ‘stick’ to the plant) sprayed on weeds as an organic herbicide. I have found this to be an ineffective solution – many weeds survive, surrounding plants are harmed. The intent is to use the toxicity in the vinegar to kill the plant which is how chemical pesticides work.
- Salt – do not use salt to control weeds. Salt is harmful to the plant growing environment as well as fresh water aquatic life.
- Use solar power in larger areas – if you have a larger area that needs to be completely cleaned of plant life, this method has worked very effectively: cut existing vegetation close to the ground, cover the area with 4-5 sheets of non-glossy newspaper and cover this with black plastic sheet (2-4ml). Weigh plastic down to keep air pockets at minimum. Keep in place for 4-8 weeks. This will eradicate the majority of plants but may also harm soil biology – after removing plastic, cover area with compost to help re-establish biology.
My favorite weed control…