Placement: Full sun, up to 6 hours of sun a day for abundant blooms, although there are a few varieties that can take less sun (Burgundy & Dark Red colored varieties can fade in too much sun). Water lilies do best in moving water that is oxygenated by a pump, stagnant water may cause them to rot out. Avoid water splashing on the leaves, and heavy wind & wave action that causes leaves to pull away from stems.
Water Depth: Water lilies are submerged plants- the roots need to be in the water with theleaves floating on the top of the water. The roots or pot should be submerged at least in a foot of water up to 2.5′ / 3′. Dwarf varieties can be in less water, the larger ones should be grown in deeper water. In natural ponds that have stiller water, water lilies can grow in up to 6′ water depth. If lilies are planted too deep, the stems can break away from the rhizome (tuber).
Fertilizing: Fertilize your water lilies around April or May, monthly until August/September. Do not fertilize your plants when they are dormant and follow the directions on the package. Use only aquatic fertilizer tablets- not fertilizer meant for soil plants- you can get algae blooms and possibly kill your fish. You don’t have to fertilize them if you have a heavy fish load, the fish waste turns into nutrients for the plants to absorb. If your lilies aren’t blooming, they may need to be divided, re-potted or need fertilizer.
Dividing: Divide mature plants when overcrowded, or have out grown their pot. In warmer areas, divide your lilies more often, cooler areas divide less often (shorter growing seasons) or every 3-4 years in late spring. If you clean out your pond, that would be a great time to deal with your aquatic plants-dividing, fertilizing, cutting back foliage, etc. Water Lilies planted directly into the pond may need to be divided every 2-3 years as they will grow faster than they will potted. A divided water lily needs at least 6 weeks of good growing weather in order to survive winter. Use a sharp, clean knife and cut 4″-5″ of rhizome on medium to large types and 2″-3″ pieces on smaller types. Make sure there is at least 1-2 side eyes per division.
Planting:Plant your water lily directly into the pond, or submerge a potted lily in 1′-3′ ofwater depth. Do not use a planting mix, potting soil or compost intended for soil plants. These mixes use a lot of oxygen as they break down and can cause your tuber to rot or cause algae blooms. Use an inert medium- top soil, sandy loam, gravel or an aquatic plant “soil”. See my blog on Planting Hardy Water Lilies for more details.
Pest Control: Water lilies get few pests & diseases. Aphids can be a problem and can spread quickly. Never use a pesticide on any pond plant that is not labeled safe for aquatic life- fish are very sensitive! A natural method is to coat the leaves of the lily infected with aphids with “Diatomaceous Earth”or DE- a whitish powder make up the shells of microscopic organisms called diatoms (avoid breathing in the dust particles).
The sharp edges of the diatoms cut the insects and suffocate them. Wait a day and spray off your lily pads with a gentle stream from a garden hose. You may have to repeat this several times until they are gone. The fish may eat some of the aphids for you and the DE will not harm fish. Another potential problem is root rot, which usually happens to potted lilies.
Dead Heading / Leaf Care: Each water lily bloom lasts up to 5 days or so, opening and closing each day until it expires. You can cut spent flowers to stimulate more blooms and to keep your lilies tidy. Dead or ugly leaves can be trimmed as needed. Do not cut the “indicator” leaves that grow out from the base of the tuber, they tell the plant when to grow in the spring.
If you have any questions email at: firstname.lastname@example.org or stop by ThePondPad.com. Kerri Bailey, owner, has been working with aquatic plants since 1989 and in the horticulture & pond industry since 1998. She has a BS in Biology and is a Certified Herbalist. See her other blogs on Planting Hardy Lilies and Water Lily Facts.