By Liza Fleming, Aquatics & Co.
Spring has arrived, your pond is up and running and looks wonderful. Your plants are beginning to thrive with the heat and sunshine of approaching summer, creating the lush paradise your water garden was meant to be.
To keep your plants healthy and growing robustly it is vital to spend some time every week throughout spring and summer on some basic, easy maintenance.
Plant maintenance
- Remove dead material such as crusted algae and dead leaves from the top of the soil
- Scrape off any re-growing remnants of algae from around the outside of the pot – filamentous algae (the stringy kind) will use any foothold it can get to rapidly become a nuisance in your pond
- Check for dead leaves – remove all of the dead leaf, including stem (particularly on water lilies) – this helps to keep the detritus from gathering on the bottom of the pond and directs the plant’s energy toward growing healthy leaves and flowers
- Deadhead flowers once they are spent – if your aim is to collect seeds, then you may need to fertilize more often to keep the plant’s energy level up
- Fertilize regularly – when leaf colour wanes or plants simply won’t bloom (particularly water hyacinth) you may need to fertilize – use an aquatic fertilizer tablet for plants anchored in soil, or a liquid aquatic fertilizer for floating plants
Plant disease and insects
Water plants tend to be more prone toward insect problems than actual plant disease. The dilemma with either problem is in how to treat it. How do you chemically treat a pond without killing your fish, or the many frogs, birds and critters that may frequent it? Biological controls, such as predatory insects, are available for many insect outbreaks and can help to prevent long-term infestations. If you do have to chemically treat a plant for disease or insects the best method is to remove the plant entirely from the pond, place it in a separate tub and treat it exactly according to the instructions on the insecticide or fungicide package. Regular maintenance and removal of dead material will greatly assist in preventing outbreaks and allow for early detection.
Common aquatic pests
- Aphids are the worst enemy of most water gardeners – there is no easy (i.e. safe) solution to them except for the age-old method of spraying them off the plants with water and letting the fish have a meal. Ladybugs are a predatory alternative. If you remove the plants from the pond you can usually spray effectively with a common insecticide, but remember, the plant will retain the chemical residue, so don’t put it back in the pond right away.
- China Mark Moth occurs mainly on water lilies and is usually easy to spot – look for a piece of evenly cut leaf stacked on top of a water lily leaf. Sandwiched in between will be a caterpillar or larvae. Remove the entire leaf and keep a close eye for further cocoons. If persistent, remove the plant and treat with Malathion.
- Red Spider Mites occur on raised leaves – marginals and raised water lily leaves. Chemicals are not very effective as the mites spin protective webbing that blocks any spray. Removal of the affected leaf will help to immediately control damage. Regularly divide water lilies so that leaf stacking does not occur.
Common diseases in water lilies:
- Crown Rot – This causes the lily leaves to turn yellow and the rootstocks to turn to mush. If this occurs, remove the plant from the pond to prevent spreading the other water lilies. If the disease is caught early enough the plant can be treated with a fungicide (such as ‘Truban’).
- Brown spot – In wetter summers, brown spots appear on water lily leaves causing rapid decomposition – remove the affected leaves and treat with fungicide.
Other troubleshooting
If your plants are simply not thriving and you can’t figure out why, look for the most bas
