Choosing The Best Pond And Lake Weed Killer | Great Days Outdoors

Choosing The Best Pond And Lake Weed Killer

Even though it may be chilly outside it doesn’t mean that aquatic weeds don’t grow and, as a pond or lake owner, you need to be vigilant in stemming that growth by choosing the best pond and lake weed killer.

“We like to think about pond weed removal as a holistic approach that we like to encourage,” says Norman Latona, founder and CEO of Southeastern Pond Management. “Once that pond vegetation is established and you get into the warmer months and have heavy stands of weed infestations in the 30 to 50 coverage range your options are pretty limited.”

“You can just live with it or you can whack it with herbicide which works but it can be costly and it is not always the best overall solution,” Latona noted.

According to Latona there are a number of things to consider when combating vegetation growth and avoiding nuisance vegetation but the cornerstone of pond weed control is to manage the water quality in a positive way.  



That means paying attention to the water alkalinity and, if it is low, late winter and early spring is the ideal time to lime your pond to bring that level up to where it is supposed to be.


pond liming

Liming your lake or pond is a great first step in the weed control process.


“The reason we want to lime in the early spring, beginning in late February and early March is that we want to be ready to start fertilizing a little bit later,” Latona said.  “I know this sounds a little counterintuitive and you are probably wondering how the heck does liming and fertilizing help prevent weeds?   The secret is that by liming and fertilizing we are producing ideal water chemistry which enhances the plankton community in the spring.  That gives the water a little tint and color which shades the bottom from intense sunlight, which helps prevent the growth of unwanted bottom rooted aquatic vegetation.”



Even though there isn’t a lot of growing activity in the winter, it is still the time to establish that base, just like you do when you apply pre-emergent herbicide to your lawn in the colder months and you have the best shot at preventing vegetation from ever getting established in the first place.

Latona pointed out that it takes three things to grow plants, soil, water and sunlight. While obviously, we can’t control the water or the soil, the one thing we can manipulate and control to some extent is the sunshine.  He also said that most aquatic vegetation won’t tolerate much shade and is pretty direct intense sunlight dependent and any steps to mitigate the intensity or volume of direct sunlight will inhibit vegetation grown on the pond bottom.  

“By liming and fertilizing we are enhancing planktonic algae growth, which is a green plant as well and we can create a shading effect and we can block some of that intense sunlight from ever hitting the bottom which is where most of the nuisance stuff grows, and it is almost like putting a shade cloth across the top of the water,” Latona said.  “If weeds do grow it is struggling and it isn’t going to grow in the massive quantities that you see in lakes and ponds that are super clear.”


lake weed killer

The application of herbicide, as well as stocking grass carp, are both great tools for aquatic weed removal.


“That is the objective and the strategy and it is really important to get a jumpstart on that shading because once you get into mid-late March and April the weeds may be winning the war and you really have got an uphill battle on your hands,” Latona added.

Once that aquatic vegetation gets a foothold it is difficult to curtail its growth because in the spring the water column is growing and introducing grass carp, who feed on that the vegetation, is an option as are lake weed killer herbicides.

“Grass carp can be effective but if the aquatic vegetation has already grown up near the surface it is difficult to shade the sunlight,’ Latona said.  It is a lot easier to shade vegetation that is growing in four to six feet of water than it is something that is just a foot below the surface.”

If you want to postpone nuking your pond with lake weed killer by introducing grass carp, when is the best time to stock them?

“It depends on the lake but generally in lakes and ponds that are shallow and have a known history of aquatic vegetation issues, then the sooner the better,” Latona advised.  “Ideally, you want to get grass carp established when there isn’t a lot to eat because you want them to be hungry all of the time and swimming around fighting for food and competing for vegetation.”

“We prefer to put them in in January and February as opposed to March and April when the weeds are already growing.  It grows so fast in the springtime that you’d have to stock 10 times as many grass carp than you really need to have any chance of controlling it,” Latona said.  “They are just a part of the strategy but they’re not a magic solution.”

How much aquatic vegetation is too much vegetation and is there a middle ground?

A lot of the vegetation issue has to do with water depth.  If you have a deep lake and the banks are cut pretty sharply down around a good portion of the lake chances are you won’t have a lot of super shallow water where vegetation can take a foothold and get established. 


lake weed killer


If there is sparse or even no vegetation, there are companies that supply habitat to simulate floating grass, lily pads plus underwater structure that can provide cover for both baitfish and predators for those ponds devoid of vegetation.  It’s the opposite side of the aquatic vegetation coin.

Latona points out that there is “emergent shoreline and vegetation” that grows in the soil around and in the shallow areas and in three or four feet of water in the marginal areas.  They will form some mats as they slowly creep outward into the open water.

“That is one of those kinds of ‘best of both world’ scenarios in my mind,” Latona explained.  “You have vegetation along the margins and the bait loves it, the predators love it and the fish utilize it for habitat for spawning, protection and ambush.  But you don’t run the risk of it growing and taking over open water and becoming a nuisance.”

Controlling aquatic vegetation is really about knowing how to get rid of pond weeds, being proactive, and starting the ball rolling early regardless of what the temperature outside is.

“When we get towards the end of February and the beginning of March it’s going to be chilly and kind of wintery and while the temperature changes the daylight is the same and that which stimulates vegetation growth,” Latona said.  “When it comes to fertilization it doesn’t matter what the air or water temperature is and the truth is that the calendar should dictate when you start fertilizing, not the water or air temperature.”

“What we are doing is building the phosphorus content in the water slowly so what when we get into April, May and the true growing season we’ve already got a phosphorous and hopefully a phytoplankton base that is going to explode as the water and air temperatures rise,” Latona noted.  “If you wait too long and are fighting vegetation, go with lake weed killer and wait until it does the job. It costs you a bunch of extra money, puts you way behind in your fertilizing efforts and you’ve wasted a bunch of time.”



Southeastern Pond Management

205-664-5596 (Birmingham office)


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