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), on stalks growing up from the rhizome (the chunky crown of the plant), 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.
The Keys to Success for Waterlilies:
Sun - Site - Size - Soil - Sustenance
Waterlilies flower most profusely where they receive full sunshine. They will perform less well in shaded situations or in cloudy cold summers.
Waterlilies do well in warm, relatively still water. The blooms will become waterlogged and sink if they are splashed by 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.
Larger koi (carp) 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”. Ducks (and in a few cases koi) may damage the leaves and the lilies may need further protection. We have experience of planting and establishing lilies in koi pools. Contact Us if you require this service.
Waterlilies come in different sizes. Catalogues often describe them in a range from Vigorous/Large through to those of Miniature growth. The most vigorous ones suit lakes and deeper water (90cm or more). The miniature ones are better suited to a pond shelf, tub or bowl, with as little as 10-15cm cover over the plant crown. For typical garden pools with a base depth of 45-60cm the ‘Small’ and ‘Medium’ varieties are likely to be most suitable. Pick the right size for success, and ask your specialist supplier for advice if needed.
Young plants are better acclimatised in slightly shallower water before being moved to their final depth. Plants of a good size can usually be put straight in at their final depth (if the water is clear), though they make take a short while to get going.
As well as lily size, it is also important to pick the right size of container to plant into. Many lilies are sold in temporary pots of only 2-3 litre volume. All but the miniature varieties must be moved on to larger containers (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. Although lilies can be grown in a soil layer on the pool base, this is not recommended for average sized ponds - it also makes future maintenance much more awkward.
The best planting soils are loam-rich with some clay content. Your own garden soil, or sub-soil, may be appropriate as long as it hasn’t been recently treated with fertilizers or chemicals. 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 of them give good results - choose the heavier brands where possible. In our UK climate, fine-mesh planting baskets are best. Use a short-lived hessian liner to help reduce soil loss until the plant roots take hold. The roots will eventually grow out into the sediments on the pool base.
In nature, the rhizomes can send their roots out into fresh soil or silt from which they can pull out the necessary nutrients. In the confines of a garden pond it is usually necessary to add nutrients. Most marginal plants don’t need much in the way of fertilizer, but waterlilies will bloom much better with feeding. Add controlled-release fertilizers to the soil when first planting the lily, and again around the start of each growing season. These slower-release fertilizers (often in tablet form) trickle out their nutrients when the plant most needs them, and if pushed down into the soil are less likely to feed pool algae (a problem with instant-release fertilizers). If specialist fertilizers are unavailable, a handful of ground or pelletized bonemeal is an alternative, ideally wrapped in a ball of clay and pushed down near the fine roots.
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.
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.