Controlling Weeds in Ponds

Aquatic weeds are a very common occurrence in many ponds across the country. They thrive in warmer temperatures so are often seen during the summer and can rapidly take over a body of water.

Aquatic weed control

When it comes to controlling weeds in water it is important that you only use products that are approved for “aquatic use”. For this reason it is essential that you check the product label of the herbicide you are using to make sure that it is ok to use. The amount of products available with this approval is limited and is generally only given to products containing the active ingredient glyphosate. Glyphosate products, such as Roundup ProActive , will only work on pond weeds that have leaves above the water’s surface. 

The Department of Environment, Food and Rural Affairs (DEFRA) has strict rules revolving around the use of herbicides in aquatic areas including ponds in the garden. If you are wanting to spraying weeds near/in your garden pond, you would need approval from the Environment Agency. This approval can be achieved by completing the following online form. 

How to apply aquatic weed control

When using glyphosate weed control products in aquatic situations, we would recommend that they are applied using either a knapsack sprayer or a weed wiper. These herbicides will only work when they are applied to weeds that are either floating or are growing above the water’s surface. 

Can you use adjuvants when controlling aquatic weeds?

It is recommended that an adjuvant is used with the glyphosate weed killer to help it “stick” to the weed leaf. At A1 Lawn, we stock the aquatic approved adjuvant, TopFilm which is ideal for the job.

Frequently asked questions

Q. Why do aquatic weeds need controlling? 

A. Aquatic weeds need controlling as they can end up covering the entire surface of the water which will cut the light and oxygen source off to fish and other plants. They also can smother more desirable plants due to the size they can grow to. 

Q. What time of year do pond weeds become a problem? 

A. Pond weeds are usually more of an issue during the warmer months when the water temperature is above 6°C. The warm temperatures allow weeds to grow more rapidly.