Patio Pond

Caring for Patio Water Gardens


Almost all pond plants prefer a sunny location. Four to five hours (minimum) of direct sun is needed before most water lilies will bloom. It is also preferable to avoid overhanging tree limbs if practical since they can cause extra maintenance with dropping leaves and/or branches.

If blooms are not a major concern, your water garden will adapt fine to any location with at least a filtered sun. In fact, light shade during mid afternoon is desirable during extreme heat spells.

Plant Care

Most pond plants are hungry feeders and appreciate a good supply of nutrients throughout the growing season.

Generally, one application of a slow release (3-4 months) aquatic fertilizer tablet about May 1 will do a good job. A second application about July 1 will improve the performance of water lilies, lotus and other heavy feeders. Waste from fish will provide supplemental fertilizer during the season.

Any spent flowers and yellow leaves should be pinched off near the base of the plants on a regular basis. It is normal for water lilies especially to shed older leaves throughout the season.

Some submerged pond plants (i.e. hornwort) do not produce roots and are simply weighted down to the bottom of the pond with lead weights or stones. However, others (i.e. anacharis) need to be placed in a small pot with field soil or a mixture of sand and field soil (no potting soil) in order for them to flourish. The pots should be topped off with gravel/stone, etc. to prevent fish from digging into the pots and disturbing the soil. If Koi fish are being kept (not recommended for patio ponds!), use larger stone (that the Koi can’t move) or place a small piece of screen over the top of the pot. If the tops grow too large and come to the surface, they can be pinched off as needed to control their size.

Fish Care

Keep no more than 2 small (2-5″) pond fish in your patio garden. If you wish to keep more fish you will probably need to add a filter system to your water garden. As they grow it may become necessary to find them a more spacious home. I would recommend common goldfish, black moors, or a variation on the common goldfish. Japanese Koi fish are large growing fish that do not adapt well to patio water gardens.

It is best not to feed your pond fish in a patio garden on a regular basis so that they will scavenge on their own for natural food such as insects, algae, etc.. that they will find in the ponds. If you do wish to feed them, try feeding them about the same time 2-4 times a week but remove any food not consumed within 10 minutes. Do not be surprised if it takes your fish a few weeks to come to the surface at feeding time. Discontinue feeding if the water begins to cloud or if you suspect your fish are suffering from high ammonium or nitrite levels (test kits are available). Also, stop feeding whenever water temperatures drop below 50 degrees (usually about late October in Ohio).

Pump & Filter Maintenance

Your pond pump (if included) should run 24 hours to help keep the water well oxygenated. This is especially important during hot summer days. Your filter (sponge or lava rock) should be cleaned whenever water flow to the pump is noticeably restricted (generally once every 2-3 weeks). If your pond pump stops running or has a reduced flow check all connections and for debris blocking the intake or outlet of the pump. It may be helpful to ‘reset’ your pond pump by allowing it to run dry for 5 seconds then returning it to the water.

Climate Control

Water temperatures above 85 degrees can be detrimental to fish and plants. During extreme heat spells (90 degrees +) it is best to partially shade your water garden during mid-afternoon. Placing a few potted plants around the perimeter to shade the sides of the pot is also effective. A more permanent solution is to sink your water garden into the ground or cut an insert into a wooden deck to lower the side out of direct sun.

Algae Control

Your water garden may go through a ‘green pea soup’ phase before your pond plants become well established. This is normal, harmless to pond fish and plants and will clear up as your pond plants grow and absorb the nutrients algae needs to survive. Do not drain your water garden and put in fresh; water, it will just repeat the same green water phase until a balance is reached.

The green film you may see form on the sides of your pot below water is normal, desirable and a sign of a healthy pond. Once balanced your pond should remain clear enough to see near the bottom of the water garden. Any excessive string algae can be scooped out occasionally. Tadpoles and snails may help also.

Winter Care

Trim back all hardy pond plants to about 3-6″ after November 1 and then, ideally the entire pool is best moved to a location with natural light but where temperatures stay above freezing. An unheated florida room or enclosed patio is a good choice. The pond pump should be disconnected from any spouting ornament and placed about 2-4″ below the water surface so that the moving water helps prevent total freezing of the surface. Another option is to replace the pump with an inexpensive birdbath de-icer, or an aquarium heater (set at its lowest setting) during the coldest winter months. Once the chance of prolonged freezing spells are past you can move your water garden to its summer placement.

If you have tropical pond plants you can bring them indoors as houseplants over the winter or discard and replace them next spring. Papyrus and umbrella palms do especially well indoors over winter. Tropical water lilies and floating pond plants are best replaced each year unless you have access to a greenhouse that stays 55-60 degrees through the winter. Any tropical pond plants you wish to save be sure to move to a warm location before the first frost. Floating plants killed by frost should be immediately removed so that they do not add to the plant debris in your water garden. Tropical pond plants should not be placed back into the water garden in the spring until water temperature reaches 65-70 degrees.

Annual Cleaning

Once or twice a year you should give your patio water garden a good cleaning. Late fall is a good time while you prepare your water garden for winter. Drain your pond and place your pond fish in a separate container (of pond water), remove all pond plants and clean out any debris that has collected at the bottom of your water garden. Refill your garden with fresh water and return all plants. Before adding back your pond fish give them a chance to adjust to any change in water temperature and treat the water to remove any chlorine that may be found in tap water. We recommend Oase “Water Prep”, “Water Prep Plus” or a similar product for this purpose. Water can be added to replace evaporation as needed during the summer. Adding a couple inches of tap water weekly does not require use of a chlorine remover unless your water supply contains chloramines (usually found only in large cities).

Cleaning can be repeated any time during the year your water becomes “dirty” with floating debris or waste. However, with proper balance and care it should not be required more than once a season.