What Is a Water Lily (Lilly) in a Water Garden and How Do You Grow It?

In a water garden, "lilly" almost always refers to the water lily (Nymphaea)—a floating-leaf aquatic plant grown for its shade, flowers, and cover for fish. You can grow one in a container on a pond shelf or floor as long as it gets roughly 5–6 hours of direct sun, is planted in heavy soil rather than loose potting mix, and is kept from covering more than about half to two-thirds of the water surface. The Greater Toronto Water Garden & Horticultural Society (GTWGHS), a club for water gardeners and "ponders" in the Toronto area, treats plants like lilies as a standard part of pond keeping, alongside pumps, filters, and heaters.

Water lily vs. lotus vs. other floaters

The word "lilly" is often used loosely, so it helps to separate the plants you'll actually meet at a pond shop:

If your goal is shade and flowers at water level, you want a water lily. If you want height and seed pods, that's lotus. The GTWGHS keyword list includes both "lilly" and "hyacinth," which reflects how often these get confused in beginner questions.

Why water lilies matter in a pond

A lily is not just decoration. Its floating pads:

• Block sunlight, which slows algae growth in the water below.
• Lower water temperature in summer, which reduces stress on fish.
• Give fish and frogs shade and hiding spots from herons and sun.
• Absorb nutrients through the roots, competing with algae for food.

The trade-off is coverage. If pads cover the whole surface, gas exchange slows and submerged plants and fish suffer. Aim for roughly half to two-thirds coverage at maturity, not more.

Choosing a lily: hardy vs. tropical

• Hardy water lilies survive winter in cold climates if the crown doesn't freeze. They generally bloom during the day and are the safer choice for a Toronto-area pond.
• Tropical water lilies flower more heavily and often have stronger fragrance, but they are treated as annuals or brought indoors in cold regions.
• Dwarf and small varieties suit tubs and small ponds; large varieties need more space and deeper water.

Check the label for the spread (how wide the pads grow) and the recommended planting depth, because both vary widely by variety.

How to plant a water lily

1. Pick the container. Use a wide, shallow pot with no drainage holes, or a fabric aquatic planting bag.
2. Use heavy soil. Fill with garden loam or aquatic soil—not lightweight potting mix, which floats out and clouds the water.
3. Set the rhizome. Place the rhizome at the edge of the pot with the growing tip pointing toward the center, and bury it so the crown sits just at the soil line.
4. Add fertilizer. Push a slow-release aquatic fertilizer tab into the soil near the roots, following the package rate.
5. Top with gravel. A layer of pea gravel keeps soil in place and stops fish from digging.
6. Lower the pot. Set it on a shelf first so leaves reach the surface, then move it deeper as stems lengthen. A common starting point is 6–18 inches of water over the crown for smaller varieties, deeper for large ones.

Expected result: new leaves reach the surface within days to a couple of weeks in warm water, and flowers appear in summer once the plant is established.

Care and common problems

• Yellow leaves: often too little light, overcrowding, or missing nutrients. Divide the rhizome and re-fertilize.
• No flowers: usually insufficient sun (under about 5 hours) or the pot is too small for the variety.
• Spreading too far: divide the rhizome every year or two, cutting away older sections and replanting the vigorous growing tips.
• Cloudy water after planting: soil escaped the pot—top-dress with more gravel and let it settle.
• Winter: in cold regions, move hardy lilies to the deepest part of the pond below the freeze line, or store the pot in a cool, frost-free spot.

Where a local club fits in

The GTWGHS describes itself as a club for water gardeners from beginners to professionals, with meetings that include speakers, a question-and-answer session, a plant table, and refreshments, and some meetings held at a nursery or a private water garden. Membership is per calendar year: $20.00 for a single membership or $25 for a family membership (two people in the same household). For a beginner deciding which lily to buy, a plant table and Q&A session are a practical way to see what actually grows in local conditions. Contact is by email, and meeting directions are on the club's Contact Us page.