Pond Plants

An Essential Part of the Eco-System

Pond plants bring a new level of beauty to any pond, but they are much more than just good looks!  Plants are the natural workers of a pond ecosystem. They use nutrients that fish are adding to the water and therefore become living filters!  Too many nutrients in the water can cause algae blooms.  Too much sun on the water can contribute to algae growth as well. While your plants are sitting there looking beautiful, they’re actively providing filtration. When plants cover 30 to 40% of the surface area of the pond, it will reduce the temperature of the pond, helping reduce algae blooms.

In addition to filtration, your plants are good for the fish.   They create a shady place for fish to relax.  Some fish will nibble on the roots of floating plants like water hyacinth or water lettuce. Both of these will spread and can be quite lovely.  Here in Colorado these are annual plants, so they will die off when the winter weather comes.  If your fish have babies, plants offer a great place for them to hide.

Pond Perennials in Zone 5  Annuals - Beautiful in Water!     Floating Plants

Water Lilies

Hardy water lilies do well in a sunny Colorado pond.  Benefits of lilies in the pond are many. The shade they provide gives shelter to fish from predators (you can't eat what you can't see!).  They shade they provide keeps the pond cool and stabilizes the water temperature from fluctuations.  Ponds in sunny locations with little or no plant life may experience more algae.  Lilies help keep the pond in balance by  providing oxygen and using up nutrients in the water that feed algae as well as blocking some of the sun.

Things to know when first getting lilies:

  • Plant in loam garden soil - not regular potting soil!
  • Use a fabric aquatic plant pot or a plastic pot with no holes.  14 to 16 inches is ideal.
    • They will grow directly in the gravel, but will float up if not anchored down and it can make cleaning out the pond or separating the plants later more difficult.
  • These plants grow as a "rhizome" and the crown should not be covered by the soil.
  • Put 2 or 3 fertilizer tabs into the soil for optimal flower color (Lilies come in a variety of colors!)
  • When first introducing a lily to the pond, put in in at about 6 inches depth, if possible.  Then, as the plant grows, lower it to 12 to 18 inches below the surface. One way to do this is to put a plastic pot under the lily pot to raise it up if you need to.

Things to know about caring for lilies:

Dividing and re-potting
  • Every 2 or 3 years the lilies will need to be divided.  A plastic container will begin to bulge - giving you this reminder to this.  If they are not divided and re-potted, they will grow right out of the pot, or be root bound and produce less flowers.
  • Take the pot out of the pond and hose off the soil.  You will be able to see that there are different rhizomes.  You'll need to cut these into separate pieces, keeping the most healthy looking ones and discarding the others.
  • Re-pot the ones you are keeping, putting some gravel on top of the soil to weigh it down and put it back in the pond.
  • Lilies do well with fertilizer
  • Add fertilizer tabs every 4 to 6 weeks
  • Push them down in the soil so they are near the bottom of the roots.
  • Make sure to remove leaves when they die or turn yellow.
  • Sometimes koi will burrow into the gravel and soil of a lily and uproot them.  Try putting some larger cobble over the soil to deter fish.
  • If koi are eating your lilies you may need to offer them other plants to nibble on like floating hyacinth.
  • If you need to protect the lily plant from the fish, there are these specialized nets that float at the top to protect lilies. They are floating plant protectors by Nycon.

Lilies will go dormant during the winter.  Cut them back to about 6 inches above the root ball.  They can stay in the pond all winter and will come back in the spring.


The Benefits of Floating Plants

Floating plants are a great addition to a pond, shading it, reducing the water temperature, and helping to reduce algae.

Floating plants are natural oxygenators and are the filter workhorse of the water.  Water hyacinths float on top of the water and even have little purple blooms that are about 6 inches high.  Their roots hang down below, filtering excess nutrients from the water.  In the southern states these plants can be
invasive as they propagate by themselves doubling their size in as little as 10 days.  But they are only hardy in zones 8 to 10, so here in Colorado  (Zone 5 on the Front Range) they offer filtration and shade to our ponds without being a pest. If they begin to overgrow just thin them out by removing some. They love hot sun! 

Floating lettuce is another great filtering plant and give some more texture to the look of the pond.  Their dusty green leaves are good in partially sunny or fully shady waters.  They are also an annual here in Colorado.

Cattails - Going in with Eyes Wide Open!

Do you love the look of cattails? Many people do, but before you plop those bad-boys in your pond, make sure you know what variety you have and how they will affect your pond.  While they do offer a safe haven for tiny fish and other wildlife, they are also a very invasive species.  These wetland plants spread their seeds through the pretty fluffy seed heads we all enjoy.  They also spread through the use of runners!  Yes!  Their rhizomatous root systems spread quickly and can take over a small backyard pond in no time.  They create a massive mat of dense roots that can be extremely hard to pull up.  

Some people have planted them in pots to help curb propagation and although it may slow them down, it won’t stop them.  Colorado Pond Pros has been called numerous times to pull out cattails, and sometimes we can’t because it could damage the liner.  Be sure you understand them before you put them in your pond!