Corn Gluten: made from corn it functions as an organic weed-and-feed. It works by keeping all seeds from germinating. Once a plant (or weed) begins to grow the Corn Gluten will not harm it. Very effective when used twice a year, in October and February. The effect lasts 6 months. The feed part is the 9% nitrogen fertilizing effect which thickens grass and stimulates the growth of all plants.
20% Vinegar: this natural acid will burn plant tissues it is sprayed on. Best to apply in bright sunlight and hot days. Spray thoroughly. Very effective on annuals; perennials may need more than one application. Be careful not to overspray on desirable plants as it is non-selective. Repeated use can acidify soils which in our alkaline soils is not usually a problem except for alkaline-loving plants like lilac.
Perfectly Natural Weed Killer: a blend of plant oils and clove oil. Best to apply in full, hot sun. Spray thoroughly. May need to be repeated on deep-rooted perennials. Be careful not to spray desirable plants.
Do not let weeds go to seed: “One year seeding; seven years weeding.”
Cover the ground: if there is bare ground, something will grow there. Cover the ground with plants or mulch to claim the space.
Tall plants out-compete weeds for light and other nutrients. Mow lawns 3” high (especially in summer) to strengthen the grass plants and shade-out weeds
Enrich the soil so the desirable plants grow strong and vigorously. Support soil life with compost tea and/or microbial inoculants so the beneficial bacteria and fungi will strengthen the plants. This will give more competition for weeds.