Healthy, hardy waterlilies (Nymphaea) can produce a succession of blooms from June right through to early September. Each bloom opens in the morning, and closes in the late afternoon, and typically re-opens each day for a further two days before sinking below the water. © www.watergardensolutions.co.uk
Waterlily leaves are produced throughout the growing season (April-October), and after a while the older, outer leaves will yellow and start to decay. This is quite natural, and the old leaves can be removed if they become unsightly.
Exotic tropical waterlilies are recommended by some sources. They have a wider colour palette, including intense purples and blues (not found in hardy lilies - until recently). However, in the UK tropical lilies will only perform well in a greenhouse or conservatory or a specially heated pot, as they require consistent summer water temperatures in excess of 21 degrees C.
Common problems - Poor siting
Poor siting is a common cause of poor flowering. Cold, shaded pools usually give very poor results. Waterlilies flower most profusely where they receive full sunshine in warm, relatively still water, and where the rhizomes can send their roots out into fresh soil or silt from which they can pull out the necessary nutrients. They will perform less well in shaded situations or in cloudy cold summers.
Lily blooms will become waterlogged and sink if they are sited too close to fountains. They will not bloom well in cold, spring fed pools; in very deep water; or in strong currents. There is generally no problem caused by the gentle currents from nearby waterfalls using recirculated water.
In koi pools, larger koi can root about in the containers searching for food, and this will severely disrupt the lilies. In such cases the lilies need to be planted in more solid sided containers with fewer holes and with a protective mesh “hood”. In a few cases, koi may damage the leaves and the lilies may need to be moved to an area of the pond separate from the larger fish. We have experience of planting and establishing lilies in koi pools. Contact Us if you require this service.
Common problems - Poor planting
Many lilies are sold in temporary small containers of only 2-3 litre volume and all but the miniature varieties must be moved on to larger containers (fine-mesh of at least 5 litre volume for medium sized lilies, 10 litres or more is better). If not potted on, they will fail to perform at their best. In certain cases they can be grown in a soil layer on the pool base - though this is not recommended for the average sized pond and makes future maintenance more awkward. The best planting soils are loam-rich with some clay content. Avoid excessively sandy, peaty, chalky, or 100% clay soils, and do not use standard bagged composts. Commercial ‘aquatic soils’ can be used, though not all give good results - choose the heavier brands where possible. Unlike most marginal plants, lilies benefit from the addition of controlled-release fertilisers when first planted up, and then around the start of each growing season. These slower-release fertilisers trickle out their nutrients when the plant most needs them, and are less likely to cause pool algae problems than instant-release fertilisers.
Young plants are better acclimatised in slightly shallower water before being moved to their final depth. The ideal depth depends on the variety chosen, ask your specialist supplier if in doubt. Good sized plants can usually be put in straight at their final depth, though make take a short while to get going.
Container-grown waterlilies typically require splitting and re-potting every three to five years for best results (or every one to two years in climates warmer than the UK). If the lily leaves are getting smaller each year, the plant is suffering from a major lack of nutrients and needs to be split and re-potted. If the leaves are crowded and pushing up out of the water, the plant also needs to be split and repotted. Check too that the plant is an appropriately sized variety for the pool size and depth - large coarse varieties do not suit small ponds.
Diseases are uncommon in established, well-planted lilies. Insect damage can occur in some cases, but changes in management are often a preferable approach to using chemicals. Blackened leaves can sometimes be due to fungal problems, or use of certain pool algicides. Contact Us if you require more detailed advice.
Right plant, right place
Some varieties/cultivars of lily are more free flowering than others, and different cultivars suit different situations. We will match the best flowering cultivars of the colour you prefer to your particular situation. Contact Us to discuss your requirements.