Healthy, hardy waterlilies (Nymphaea) can produce a succession of blooms from June right through to early September. Blooms usually open in the morning, and close in the late afternoon, and typically re-open 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 + Soil
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 warmer, relatively still water. The blooms will become waterlogged and sink if they are splashed by fountains. They do not bloom well in cold, spring-fed pools; in very deep water; or in strong currents. Gentle currents from nearby waterfalls (using recirculated water) will not be a problem.
The depth of water is important. Waterlilies come in different sizes and suit different depths. 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 size to suit your site, and ask your specialist supplier for advice if needed.
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 potting composts. Commercial ‘aquatic soils’ can be used (though not all brands give great results) - choose the heavier brands where possible. In our UK climate, planting into fine-mesh baskets is the preferred option. Use a short-lived hessian basket-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. (Lilies can also be grown in a soil layer on the pool base, but this is not recommended for average sized ponds and it makes future maintenance much more awkward.)
Planting into the right size of container has a big impact. Many lilies are sold in temporary 2-3 litre pots. All but the miniature varieties must be moved into larger containers (at least 5 litre volume for medium sized lilies, 10+ litres is better). If not potted on, they will fail to perform at their best.
In the confines of a garden pond it is usually necessary to add extra nutrients. Most marginal plants don’t need fertilizer, but waterlilies flower 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, to boost blooming rate. 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 soil 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 soon outgrow small ponds.
Waterliles and fish
A few goldfish are no problem with lilies. The fish waste will help to fertilize the plants, and the fish can eat some of the insects that might damage lilies. Unfortunately, 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 solid-sided containers with few holes and with a protective mesh “hood”. Ducks (and in a few cases koi) may also 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.
Diseases are uncommon in established, well-planted lilies. Insect damage can occasionally occur, more often in newly planted young plants. Changes in management are a preferable approach to using chemicals. Blackened leaves can be due to fungal problems, or 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.
For information on waterliles and other aquatics from an international perspective, visit the IWGS