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Day bloomer?

Night bloomer?

Nymphaea 'Elysian Fields'

There are some really wonderful hardy waterlilies of which I am fond, but my personal preference has always been for tropicals, since only the tropicals offer flowers in a full rainbow of colors, including blue and purple colors ... and tropicals also offer night blooming varieties as well. Although tropicals are not reliably winter hardy in most climates, they produce far more flowers than the hardy lilies, and they bloom late into the summer and fall, long after the hardy lilies have stopped blooming for the year.

Once having decided that tropical is the way to go, the next lily dilemma is: night bloomer or day bloomer? When considering the possible choices of waterlilies for a given pond, we take into account both the size of the pond and the available sunlight. We know that waterlilies need at least five to six hours of direct sunlight daily in order to bloom well. For some reason, new pond owners often over-estimate how many hours of sun they have on their ponds. Unless they have actually timed their daily sunlight, they are usually only making a guess. When I am not convinced that a customer really knows how much sun they have, I encourage them to postpone their lily purchase until they have actually timed the duration of sunlight on their pond. If they have only four to five hours of sunlight, we can recommend one of the purple or blue viviparous lilies which may perform well in limited sunlight.

There is often an unspoken presumption among novices that a night blooming waterlily does not need as much sun as a day bloomer ... it blooms at night, right? Knowing that they do not have much daily sunlight on their pond, they may assume that a night blooming lily is what they should purchase. However, night blooming lilies also need the minimum five to six hours of daily sunlight in order to bloom reliably.

I find it is important to question the new pond owner so that we can discuss how big the pond is and how much sunlight it gets. Then we can decide which waterlilies would be appropriate choices for their situation. I recently had to refuse to sell the giant waterlily, Victoria ‘Longwood Hybrid', to a customer whose tiny pond was 3’ x 4’ (1m x 1.2m). She really wanted that Victoria, and could not be persuaded that her pond was too small for this plant, whose individual leaves can grow bigger than her entire pond! I was stubborn in my refusal to sell the plant, and I think she went away angry. But Victoria is too rare a plant to consign to such an ignominious fate!

Along with the false assumption that a night blooming lily does not need much sunlight, there may also be a presumption that since it blooms at night, its flower would never be seen during the day. It is helpful for hobbyists to be aware of the blooming cycle of a night blooming lily. While true that night blooming lilies do not open their flowers until after dark ... it is also true that the same flower often stays open until 9 or 10 am the following morning. In fact, if the morning is cool, rainy or overcast, the flowers of night blooming water lilies often remain open until noon!

Without the above information, you might reject the opportunity of enjoying a night blooming lily, and buy several day blooming lilies instead. So, what happens? You faithfully visit your pond every morning before you leave for work ... and no flowers are open. You come home from work ... and no flowers are open! The only time you get to see your day blooming lilies in flower is on the weekends, because their flowers work the same shift as you ... from 9 to 5! The irony in this situation is that if a night blooming lily had been chosen for your pond, you would see the open flowers every morning before you went to work, and again in the evening, after dark.    

Day blooming lilies, like night bloomers, can be variable in their hours of opening and closing. A very warm mid-summer morning with high humidity can sometimes cause day bloomers to open at 8 am and stay open until 7 pm that evening, even though they normally open between 9 am and 5 pm. A sudden drop in temperatures in late fall can cause both day and night blooming lilies to stay open for 24 hours ... they are chilled into a torpor which arrests their normal routine.

There are a few day blooming tropicals which are well known for often having flowers open from dawn to dusk in the summer months. ‘Wood’s Blue Goddess’ is such an example, and many new hybrids of Nymphaea ampla often share this trait. If there is room for only one lily in the pond, then these make an excellent choice for their prolonged hours of bloom.

If the pond is big enough for two waterlilies, I prefer to resolve the day bloomer vs night bloomer dilemma by suggesting one of each. This is a perfect choice, since it provides the possibility of having a flower open at almost any time of the day or night.

Night blooming lilies have flowers which come in red, pink or white. Obviously, a white flower would be the most visible at night if there is some ambient light near the pond; if a red or pink flowering night bloomer is chosen, it may require a spotlight directly on the pond so that the flowers can be easily appreciated at night. This fact should be considered before choosing the color of your night blooming lily. We should note that a spotlight on a pond will NOT delay the normal opening of night bloomers’ flowers. Of course, if you often visit your pond with your early morning coffee, any color night bloomer will be in full, glorious bloom. This is also the best time to photograph night blooming lilies ... the early morning light is perfect to give you accurate colors in your photos.

A small pond which measures 4 feet by 5 feet (1.2 by 1.5 m) is obviously too small for both a night bloomer and a day bloomer ... they would be growing on top of each other very quickly. However, a pond measuring as little as 4 feet by 8 feet (1.2 by 2.4 m) could be large enough for both a day bloomer and a night bloomer, if you know how to manipulate the growth of the plants.

Waterlilies, like most other plants, are controlled by the size of the pots they are grown in, and the amount of nutrients available. By planting a waterlily in a relatively small pot, you can restrict root growth and the ultimate size of the plant. So, instead of planting into a 14 or 16 inch (36 or 41 cm) pot, use a 10 inch (25 cm) pot. Instead of fertilizing every two weeks during the growing season, fertilize every three weeks instead. This will result in somewhat smaller plants but they will still bloom normally. And there is still one more secret for keeping the lilies in bounds: remove some leaves!

A well grown, mature waterlily does not need the constant 15-25 leaves that it may have during its peak growth. After all, it is the flower we admire most, right? The leaves may be nice, but who needs more than seven or eight of them? Not me, not you . . . and not the lily, either! Once the plants have grown large enough to cover most the surface of your pond, this is what you should do:

Every week, trim off all the older, outer leaves on each plant, leaving only the six or seven youngest floating leaves at the center of the plant. This is quite enough leaf surface for the plant to continue blooming as it normally would, but it prevents the plant from taking up too much surface area in the pond. This does not stunt the lily, and its leaves will remain as large as usual . . . but by removing the excess leaves, the plant will not overwhelm the space available. Most people like to see some water surface between the waterlilies, and this selective pruning allows you to control how much of your pond surface is covered with leaves.  

This weekly reduction in older leaves works equally well for day bloomers and night bloomers. Note the before and after photos of the tropical day bloomer, N. ‘Foxfire‘, growing at the New Orleans Botanic Garden. Grown in a 16 inch (41 cm) pot, this large growing variety has multiplied into three plants, and had a spread of more than 10 feet (2 m). I removed about 36 older leaves, which reduced the size of the plant to about six feet (1.8 m) in diameter. This left more than thirty mature leaves on this specimen, more than enough to keep the three plants in constant bloom.

Knowing that a waterlily does not need more than six or seven floating leaves to stay in bloom, we must be aware of those times when we may have two or more lilies in the same pot, as illustrated in the photo of ‘Foxfire‘.

Top left - N. 'Foxfire' at 10 foot (2 m) spread
Bottom left - after pruning to 6 foot (1.8 m) spread

Occasionally, new plants appear alongside the parent plant. By lifting the pot to the water surface, it is easy to see that there are two or more distinct growing points from which leaves and flowers emerge. Although this crowds the root system, two day blooming lilies can continue to grow and bloom well in a ten inch (25 cm) pot. (This is NOT often true for night blooming water lilies ... I told you they are greedy!)

So, you must be observant and use caution: if you are not aware that you have two plants in one pot, and you remove all but seven leaves from that pot, then one plant may have only four leaves, and the other plant only three leaves ... not enough to keep them in bloom! When you have two day blooming waterlilies in a pot like this, you either need to remove one of the plants, or leave at least six new leaves on each plant. They will continue to bloom normally, although the size of the leaves and flowers will be somewhat smaller. You will now have twice as many flowers from that pot, on plants whose overall size is reduced. In a pond where space is at a premium, that is a good thing!

We have mentioned that night blooming lilies have two bad habits ... they grow too big and they multiply too easily. We have already discussed how to keep them in bounds by removing excess leaves. Now we turn our attention to their habit of rampant multiplication, something which is an unlikely problem with most day bloomers. 

Many varieties of night bloomers will multiply by sending out short runners from their crowns, which can root into the soil in the pot. Or, they can send up new plants from growing points along their buried tuber. When you see small leaves appearing on the water surface, along with the larger mature leaves from the main plant, you are being warned that multiplication is taking place. The photo of a red night blooming lily clearly shows some of these smaller leaves among the parent plant’s mature leaves.

By lifting the night blooming lily to the water’s surface, it will be easy to see these offshoots, and remove them by the roots or runners with a sharp knife. This can be done without hurting the parent plant, even if a few of its roots are severed during the surgery.

As we have already mentioned, you can usually get good blooms when two day blooming lilies are in a ten inch (25 cm) pot, as long as they are fertilized on a consistent schedule. However, with multiple night bloomers in a ten inch (25 cm) pot, the parent plant will soon stop blooming, and all you will have is leaves . . . and eventually a lot of tubers. This is fine if you want to propagate that particular night bloomer for next year’s pond, but most pond keepers would rather have wonderful blooms instead a pot full of small leaves.

Because night bloomers are so prone to multiplying, removing the unwanted offspring must be done every few weeks, whenever the small leaves of new plantlets are observed. This is not much of a chore and can be accomplished in just a few minutes.

So, the dilemma is resolved ... we certainly may have the pleasure of an exotic night blooming waterlily in our pond ... And if there is room, it will make a fine companion for any day blooming lily we may choose. Beauty by day and by night . . . how lucky can we be?