In an effort to avoid bankruptcy heating waterlilies over the winter, Charles Leach reports on his -


View of snow outside
from the sun room

Experiment to Save Energy with
Mini-Heaters - Part 2
(Click here to review Part 1)
by Charles Leach, Ohio USA - Zone 6
Click images to enlarge

Buggy Summer & Strange Fall: The past summer and fall were hard on our tropical waterlilies. For starters, given a summer and fall with almost no rain, we spent most of our time watering terrestrial plants rather than giving the waterlilies proper care. While we weren't paying sufficient attention, weevil infestations twice forced us to totally cut back most of our tropicals in the in-ground pools and tubs.

For some strange reason the plants in our above-ground tubs, that we pass by constantly, had practically no weevil damage while the plants in the more out of the way in-ground pools were decimated. In addition to the weevil problem, whitetail deer discovered that the leaves of waterlilies were a real treat in a world in which all other vegetation was desiccated. In addition to eating all the leaves, as they also did with the hardy lilies, they often pulled the less securely anchored tropicals out of the pots. Especially late in the season, when they should be storing energy to get them through winter inside, I would find leafless crowns of tropicals floating or even laying on the ground first thing in the morning. Our one 'Green Smoke' was victimized so often that it was barely alive when brought in for the winter. In the decades we have been growing waterlilies deer have never bothered them until the last two years.

In order to give them time to form tubers, we usually bring our tropicals in just before the first freeze, while they are still actively growing, but this year days got shorter, temperatures fluctuated radically over an extended period and many confused tropicals seemed to be headed toward dormancy, some crowns turning an unsightly black or starting to mold, with no prospect of frost to trigger action on our part. Finally, at the beginning of November I decided to end summer vacation for our tropicals and bring them in. By then it was too late for some and they died once inside without forming tubers. Particularly hard hit seemed to be several night bloomers, 'Red Flare', Nymphaea rubra, a pink we are evaluating, and 'Trudy Slocum'. Several day bloomers, including 'Green Smoke' and 'Director George T. Moore' were in very poor condition for weeks after being brought inside. In all our years of raising tropical waterlilies, last year was the worst as far as transitioning them from outside to inside.

Slow Starters: A little more bad news was that one addition to our collection, 'Frank Trelease', purchased to winter over in order to give it a head start, was dying back and had to be moved to what I call triage in a heated and well lit aquarium. Having new plants barely hang on for some time isn't all that unusual for us. We have had some take several seasons to establish themselves. What we purchased as an N. "stellata" tuber took three years to bloom and turned out to be a red night bloomer instead of the blue day bloomer we expected. Hardy lilies 'Denver' and 'Hermine' didn't bloom or grow enough to divide until the third year when I threatened to compost them. Given the threat they took off, bloomed like crazy and have been exceptionally prolific ever since. My advice is, if all else fails, try intimidation.  

A reviving 'Frank Trelease'
in one of our
triage aquariums

Triage: What I call triage came about as a result of a failed attempt to sprout Victoria cruziana seeds. We set up two 20 gallon aquariums and carefully followed Victoria Adventure directions but the precious seeds refused to sprout. To add insult to injury Euryale ferox seeds, which supposedly sprout and grow like weeds for other people, in the same aquarium sprouted and quickly died. I was about to conclude that the set up was cursed when a few tropical waterlilies that were dying back revived in the aquariums. Since then these aquariums have become an integral part of our wintering over facilities. Not very energy efficient perhaps but quite effective in reviving tropicals starved for light and or heat. The key to success in perking up declining tropicals in Triage seems to be catching them before they completely die back.

We also use the triage aquariums to give newly acquired tropical lily tubers a head start to wintering over. At the left are baby 'Foxfires'. When planted there were two tiny detached sprouts and three tubers. Two weeks later the plants are well established and two of the three tubers have sprouted. I highly recommend starting tropicals in this manner, with water temperature held at approximately 86° F (29 C) during the winter. Handled properly you will have established plants when summer comes rather than bare root starts that may not do much until late in the season if then.

Baby 'Foxfires'

Late Entries: In mid-November I was about to add several generic red night bloomers, from the so-called "stellata" tubers, to the compost heap when it occurred to me that they might be used in the test instead. The thought of composting them was painful because they were magnificent plants; practically identical in every way to 'Mary Francis', which is my favorite red night bloomer, and far more vigorous through the strange fall than the 'Red Flares' next to them in the same pool.
Similarity to 'Mary Francis' was the problem. I was afraid that, if kept, they might somehow get confused with 'Mary Francis' and possibly contaminate the gene pool. For now they have been given a reprieve and are wintering in our basement, three small ones in six inch pots with mini-heaters and three larger ones in five quart pots; one with one heater, one with two and a control with none.Even though they were left out through a couple of below freezing nights and the foliage was dying back, the crowns seemed to be viable and within a couple of weeks the ones with heaters in the pots were sprouting.
The image at the right, taken Christmas Day, shows the generic red in a basement tub. The lush leaves at the top of the photograph are from plants with mini-heaters in pots a little over a quart or liter in volume. The less lush leaves at the bottom are from a plant in a five quart size pot. Evidently the plants are a little happier in the smaller pots where the mini-heaters raise the soil temperature a bit more. An early indication of the effectiveness of the mini-heaters was that the control in the pot without a heater eventually rotted away.    


The Lighting Factor: As you may recall, we are testing mini-heaters in two areas, a sun room with filtered natural light and in basement tubs with artificial light. In both areas lighting may be as significant a factor as temperature. I already know that some varieties, such as 'Green Smoke' and 'Midnight' need more light to thrive than has been available in our sun room. Some varieties such as 'Red Flare' and N. rubra barely survived the filtered light in the sun room last year without going dormant and the mini-heater in the 'Red Flare' test pot didn't help this year. The 'Red Flare' control without a heater went dormant within two weeks after being repotted and brought inside, and the one with the heater in the pot was dormant by the fourth week.
The problem seemed to be that the summer and fall that went by with hardly a cloud in the sky had given way to a winter so overcast that there was very little sun at all. Therefore there was insufficient natural light for most tropical lilies in central sun room pools and end tubs. When the two 'Mary Francis' and 'Texas Shell Pinks' in the sun room pool, that had thrived last winter, started to die back we knew that supplemental light had to be provided. Our solution, given the need to move quickly, was 65 or 120 watt grow light bulbs in fixtures that could be clamped to ceramic blocks left over from a reconstruction project. Not very attractive, but they seemed to perk up the plants that were not too far gone.   

A potential problem with the test plants in the basement tubs is that some tropical lily varieties, such as 'Red Flare', don't seem to thrive under our T-8 fluorescent lights while others, such as 'Hickory Bend Ruth', flourish. We had to cut leaves off of Ruth on Thanksgiving Day because it was already mugging the 'Leopardess' in the same tub. A comment about 'Antares' in the Encyclopedia of Water Garden Plants ("Stands up well to artificial light") indicated that others have noticed that some varieties like it better than others. I wish we had ideal and uniform lighting conditions for all the plants in this test but that isn't the case and we will have to attempt to assess effect of lighting on test results.

Test Procedure: Harking back to my decades in product evaluation and development, each variable (individual pot) is being inspected weekly with plant condition, soil temperatures, and water temperatures recorded in a composition book along with any deviation from original parameters. Readers will not be tortured with full details but they are important when the time comes to reach conclusions.

Commercial for Heat Mats & Accurate Thermostats: Our first effort to be more energy efficient in wintering over tropical lilies and some other tropical plants with floating leaves was use of heat mats plugged into accurate thermostats. We went that route initially because of bad experiences with electric heaters that warm the air around tubs in the greenhouse. Mechanical thermostats on the units we tried were nearly useless. Heaters often failed to come on when required and once on they usually failed to shut off, even when air temperatures exceeded 100° F (38 C) on sunny days.

To overcome the problem I bought heaters with digital thermostats that could be set to nearly exact temperatures, but rather than solving the problem it turned out to be a disaster given the constant power interruptions in our area. Even a momentary flicker in power, too short to kick our generator on, would cancel out the thermostat settings and our precious plants would be without heat. In addition to that problem, heating an entire greenhouse instead of heating only the water in the tubs was not energy efficient.

As noted in Part 1 of this series, we experimented last winter with using heat mats, underlaid with insulation, under some of the tubs on the floor and all the smaller tubs on the shelf in our attached greenhouse. These mats, plugged into an accurate thermostat, have worked like a charm and should more than pay for themselves in a couple of years given current energy costs.  

Happy 'Mrs. Edwards Whitaker' and other babies growing in a four
gallon container on the shelf
With only 40 watts / linear foot for the 21" (53 cm) wide mats under the 40 gallon (151 liters) tubs on the floor and only 20 watts / linear foot for the 12" (30 cm) wide mats on the shelf, they are not going to warm water much more than 10° F above air temperature but that saves a lot in overall heating cost. Looks like they will have to be trimmed back to keep them in the container very soon.  

Happy 'Midnight'
in a 40 gallon floor tub
on a heat mat
Room temperatures in the greenhouse where these happy plants are growing have been as low as 62° F (16 C). Even if you don't choose to go with the heat mats, I would highly recommend plugging heaters with mechanical thermostats into an accurate thermostat and that those with digital thermostats be avoided.  
Commercial for viviparous tropical waterlilies: Our viviparous tropical lilies were not included in mini-heater test because, based on previous experience, keeping the greenhouse they are wintered in above 65° F (18 C) with an occasional dip to as low as 62° F (16.7 C) is all that is required to winter them over. My favorites for winter blooms are 'Mrs. Martin E. Randig', 'Patricia', 'Paul Stetson' and 'Queen of Siam' that have bloomed well all winter in the past. 'Lindsey Woods', a new addition, has bloomed well so far this year although the flowers are small. Between Christmas and New Year's I took photographs of a few of the viviparous lilies in bloom in our attached greenhouse.  


'Royal Purple'

'Queen of Siam'

'Paul Stetson'

'Margaret Mary'

'Lindsey Woods'

How the mini-heaters are working so far: So far so good but we have not reached the coldest part of winter, when room temperatures may drop significantly, and it must be noted that mini-heaters do not bring back the nearly dead or compensate for insufficient light. Plants have to be viable for the heaters to help get them through the winter inside. Some varieties in the sun room are obviously unhappy, a couple actually going dormant, but this can be attributed to insufficient light rather than insufficient heat or to the fact that some varieties, especially night bloomers, tend to go dormant no matter what. In the last week of November I had a conversation with a very knowledgeable man with a well-known nursery in Florida about the availability of a night blooming variety that I wanted to add to my test. "All the night bloomers have gone dormant by now," he said. When I told him that we have kept some varieties, such as 'Mary Francis' and 'Texas Shell Pink' growing and blooming all winter, he was amazed.
At this point I think it is safe to conclude that the mini-heaters that work are keeping the plants warm enough so far. Two of the Junior aquarium heaters from Wal-Mart and one of the Hydor mini-heaters were replaced early on in the test however because they didn't provide much heat. A couple of the Junior heaters that were getting extra hot, registering readings as high as 112° F (44.4 C) were moved away from the plants. Otherwise the concept seems to be working fairly well as evidenced by the image below right that shows the difference between a 'Mrs. Edwards Whitaker' with a mini-heater and the control without a heater.  
Shortly after this photograph was taken the control was moved into triage to recuperate but did not survive. 'Hickory Bend Ruth', 'Pamela', 'Wood's White Knight' and 'Texas Shell Pink' with mini-heaters are also obviously more vigorous than controls without heaters while "H.B. Pink Wisp", 'Emily Grant Hutchings' and N. rubra controls without heaters all died back while their counterparts with mini-heaters survived if not thrived.    

Part 1 in WGI ONLINE Journal 2-4

WGI ONLINE Journal Table of Contents

Water Gardeners International
Home | Join WGI | Members' Exclusive | Gateway to Water Gardening