What Is a Safe Way to Kill Weeds Around My Pond That Won't Harm My Fish?

Ponds are green landscaping features. They replace energy-thirsty, expensive lawns, as well as add beauty to your home. Herbicides are highly effective at keeping pond areas free of weeds, but they're not the only solution. Learn safe ways to kill weeds around a pond that won't harm fish, including chemical, mechanical and earth-friendly solutions suggested by expert gardeners.

Not all chemical options harm fish, and some provide effective control for weeds around ponds. Fluridone is a slow-acting herbicide that's one of the safest to use on weeds around your pond, according to Ohio State University Extension experts. This type takes from one to three months to kill weeds, and pond water can be used for irrigation or even as drinking water during that time. Glyphosate herbicides are also safe and effective when applied directly to plants. These herbicides are effective for spot-spraying or dabbing on young weeds, according to Better Homes and Gardens experts. Smaller weeds need less herbicide to kill, especially if you apply it accurately using a sponge-tipped plastic "dabber" bottle from office supply stores. Remove dead weeds before rains get a chance to flush any residual weedkillers into ponds or groundwater. Use any herbicides before weeds spread their seeds and only in strict compliance with manufacturer's instructions.

Green weed killers are environmentally friendly ways to kill the weeds around your pond, without harming your fish, pets or any beneficial insects in the garden. Plain boiled water poured onto weeds kills them very effectively, especially those that appear in the cracks between paving stones around your pond. Handle boiling water with care and ensure it does not run straight into the pond, scorching nearby fish. Alternatively, try freshly squeezed lemon juice undiluted and applied directly to the weeds. Lemon juice kills the unwanted plants within a day or so.

Mulching prevents emerging weeds from getting the sunlight they need to produce food by the process known as photosynthesis. Existing weeds are smothered to death by a thick layer of mulch. Choose mulch materials that suit your pond location. Common mulches include wood chips, grass cuttings and gravel chips. Hay or straw mulch can contain weed seeds and breaks down too quickly. Bark chips and small stones used in bulk, such as gravel, add a decorative feature while suppressing and killing weed growth.

Cutting or pulling up the unwanted plants is a fish-friendly technique for weed control in gardens with small ponds. For the best results, attack weeds by pulling them up, mowing them down or cutting off young weeds early on in their growth cycle. Pick off leaves to starve the plants, and use pruning shears to cut the taller weeds later on in the growing season. This method's hard on your back for more than a few weeds. The sheer amount of physical labor involved in using this system for larger plots makes it difficult to sustain. Better Homes and Gardens experts advise gardeners to be careful pulling up unwanted plants. This is because the soil disturbance created by removing weeds can cause dormant weed seeds to grow in the newly "vacated" open spots.