Water lily care
Water lilies are very heavy feeders, they need fertilizing at least once every two years in order to thrive and flower well. Ideally you should fertilize your water lilies in Winter with a slow release fertilizer when you divide and re-pot them. Small, young or malnourished Water lilies may be fertilized without the need to divide by poking a hole in the soil near the rhyzome and adding a tablespoon of slow release fertilizer such as Osmocote or Nutricote for flowering plants. Slow release fertilizer is the best to use as it release slowly into the soil to feed the water lily whereas if you where to use something that dissolves quickly such as blood and bone or cow manure, while the water lily might respond well initially, it will taint the water. Osmocote or Nutricote will not harm any fish or aquatic animal life.
Water lilies also require at least five hours of sunlight to flower, yellow and apricot ones, a little less sunlight is required.
Water lilies don't like splash either so make sure to place your plants away from the splash of a fountain or cascade as they react as if it is raining and close up their buds or just do not form buds.
Winter is a great time divide and re-pot your water lilies as this is when they are dormant. The rhyzomes are a little like potatoes and have roots and eyes on them where the new shoots appear. Find the "eye" and cut with a sharp knife into clumps around the size of a tennis ball. The more rhyzome you leave on the plant the more advanced and successful the plant will be.
Using a pot around the 180ml size place a sheet of newspaper on the bottom to cover up any holes which stops the soil from leaching from the pot when it is placed in the water.
Fill the pot up with a heavy soil such as mountain soil or better still a specifically designed aquatic mix.
Add a tablespoon of slow release fertilizer or a couple of aquatic plant tablets.
Hold your divided water lily in the centre of the pot and scoop soil around the rhyzome until the soil is up to the top of the plant with just the "eye" showing. The soil level should be around five centimetres down from the rim once soil is compacted down with your knuckles.
Add a layer of washing coarse sand a couple of centimeters thick. This acts as filter from the soil leaching out when place in the water.
Finally add a layer of river pebbles or the like which acts a mulch keeping the plant in the pot and protects the fresh young roots and leaves from marauding fish.
Water down softly with a hose spray and place in the deepest part of your pond where it is away from splash and will receive the most sun.
It is always beneficial to your pond's water clarity to add two to three submerged aquatic plants per water lily. The more plants, the less algae you will have! https://www.youtube.com/watch?v=LlmtzSC4OjY&t=10s