Read about Steve Stroupe

The article below expresses the opinions of the author and must not be considered a product
endorsement by WGI. The author has no vested interest in the products described.
Methods may not apply to all growing conditions, soil types, or all varieties of waterlilies. 

N. 'Laydekeri Fulgens' spring 2008
See large image for cultivation details

Fertilizing Waterlilies
One Grower's Perspective

by Steve Stroupe, Alabama USA
Click images to enlarge

This is a simple article written about a relatively simple activity ... fertilizing and potting waterlilies. None of what I’m about to disclose here is revolutionary or novel, yet this information doesn’t seem to be widely known or utilized by the average homeowner or pond installation contractor in more than a few cases.

The performance of the average waterlily in the average water garden is usually quite unimpressive. There are two primary reasons for this: ignorance or indifference. Ignorance because the homeowner or contractor just doesn’t know how to provide optimal growing conditions for this plant, or indifference because the knowledge is available but is viewed as too much trouble to implement ... especially when it’s time to fertilize or divide. Additionally, this underperformance may not ever be perceived as a problem since mediocre performance is the norm more often than not.

The water garden industry itself has been complicit in the neglect of this problem ... sometimes inadvertently and sometimes willfully. The industry has been much too complacent about fertilizer innovation, preferring instead to over-rely on outdated fertilizer tablet methodology as the only way to accomplish aquatic plant fertilization. With the exception of a single transient example, the water garden industry has also expressed little or no interest in slow or sustained-release fertilizers, preferring the short term view instead which believes that this technology would reduce consumer fertilizer sales.

Tablet fertilizers for aquatic plants have been the industry standard for fertilizing waterlilies long before the first specialty aquatic tablet was manufactured in 1991. Tablets are certainly one way to assure that the plant gets a steady supply of nutrients, but are quite expensive and extremely labor intensive to apply.

This was not such a problem in the 1980s and well into of the 1990s when water gardening in the US was transitioning from a mail order specialty into a mainstream product line at local nurseries. Waterlilies at that time were new, mysterious, and expensive, so most people would follow the instructions for proper fertilizing with tablets quite religiously. A typical application rate was two 5 gram tablets per gallon of soil every two weeks or month. After the novelty wore off and ponds started getting larger and sported more plants, less and less people seemed inclined to adhere to an optimal fertilizer regimen. When gravel ponds invaded previously held bare liner territory, plant fertilization became even more problematic for the average homeowner.

Since tablets are so much trouble, then what’s the answer?

A fertilizer which could coax maximum performance out of waterlilies, but needed to be applied only once every 1 to 2 years?

It’s already here... 

Nutricote is a Japanese-manufactured, patented, polymer (oleofin resin) coated sustained-release prill* fertilizer which was developed and/or utilized for rice paddy fertilization in Japan, so it can easily be called a professional aquatic plant fertilizer. There are a plethora of peer-reviewed papers available on Nutricote’s outstanding performance in rice paddy fertilization. Nutricote’s primary release mechanism operates on soil temperature, not relying on ambient moisture levels like standard Osmocote and its imitators, which make them largely unsuitable for aquatic use. Additionally, Nutricote has a much flatter release curve than standard Osmocote even in terrestrial applications.

Nutricote works just as well under water as it does in terrestrial applications, which is why it is such an excellent aquatic plant fertilizer, and is THE commercial fertilizer of choice for most commercial growers in the US who grow aquatic plants sub-aquatically. This amazing technology also allows the fertilizer to follow the natural physiology of the plant, in effect going “dormant” with the plant in cooler weather and “waking up” with it in the spring.

“Nutrient supply through Nutricote nicely matches the physiology of plant response to temperature. The release rate of Nutricote is not significantly influenced by soil moisture levels.” (Florikan website)

While soil moisture plays a vital part in the initial activation of the prill, (dissolves the fertilizer inside the prill), pH and soil composition can affect release performance in a very minor way, the gorilla in the room here is soil temperature ... The truly exciting thing about Nutricote as far water gardening goes is that now homeowners as well as growers can produce incredible plants without that cumbersome, invasive, horribly expensive, and problematic tablet-jabbing nightmare.

Since Nutricote release curves are based upon a uniform 77° F (25 C) [greenhouse] soil temperature, a 360 day formula can easily last two seasons or more ... even in the deep south of the USA. Temperatures less that 77° F (25 C) will cause Nutricote to slow its release rate, while temperatures over 77° F (25 C) will speed it up. Nutricote application rates are also based on USDA Hardiness Zones or Nutricote “Regions” which are numbered 1 (coldest) thru 4 (warmer) and then “Greenhouse” (warmest) in order to help growers to use the correct formulation.

Nutricote Control Release Fertilizer (CRF) is available in release formulas ranging from 70-540 Day release durations or “Types”, with or without micro-nutrients, and in a variety of NPK formulations. Nutricote is exported from Japan in bulk to selected “blenders” throughout the US who then offer various standard and custom blends to their local grower markets. Florikan in Sarasota, FL, for instance. For more information on Nutricote:

Technical Information (.pdf)
13-13-13-Nutricote (.pdf)

So are tablets completely obsolete? Not at all. Since Nutricote’s formulas require a “kick-in” period to start releasing their nutrients which is roughly equal to 10% of the total days of release duration, (Type 360 takes 30 days to kick in ... Type 100 takes 10 days, etc..) tablets are a good way to supply some readily available nutrients immediately, especially if an established plant is being shifted up into a larger container. Upon occasion, and for whatever reason, a nutrient boost may be required in between fertilizations, and tablets work well for that application too. Lastly, tablet fertilization is deeply ingrained in the US waterlily hobby psyche, and even an incredible product like Nutricote will have some difficulty unseating this habituated tablet fetish until a baseline level of increased awareness is reached by consumers and contractors. Some growers already transitioned to Nutricote some time ago, and it will only be a matter of time before hobbyists come on board too and will start to enjoy waterlilies like they’ve never before experienced ... and with virtually no effort with fertilizing.

Nutricote can be purchased by growers direct in 50 pound (23 kilo) bags from US blenders such as Florikan ESA in Sarasota, FL or from local horticultural supply distributors throughout the US, although the distributors usually carry just a few formulations, so it may be worth the extra effort to contact a regional blender for the precise formulation needed.

Serious hobbyists with sizable waterlily collections would be better off going this route too, since the cost of an average formulation in a 50 pound (23 kilo) bag FOB origin (freight not included) ranges from US$75-$95 and will last indefinitely if kept reasonably cool and dry. A 5 gallon (19 liter) bucket and some silica gel desiccant works extremely well for storage.

Hobbyists can buy Nutricote retail in 1 pound (.5 kilo) and 2 pound (.9 kilo) containers under the trade name “Red Dynamite Plant Food” (For Flowers & Vegetables). This is actually Nutricote Type 270, 13x13x13 with Micronutrients.

How To Grow Incredible Waterlilies with Nutricote --
by the numbers

1) FULL sun ... the more sun the better.
2) Rich, heavy dirt in either planting pockets, bags, or pots ... NOT gravel!!!
3) Room to grow. 16”x7” (41cm x 18cm) is a considered a minimum size for a standard waterlily pocket, bag, or pot.
4) Variety or cultivar
5) Fertilizer!  

N. 'Helvola'
Cultivation details with large image

Full sun is self-explanatory. To bloom profusely, waterlilies need a minimum of 6 hours of direct sun per day. Most can get by on less, but will not bloom profusely. Some varieties do better than others on less light.

Good soil is a must. A heavy soil with well-composted organic matter is ideal, but any heavy garden soil will do. It’s seldom necessary to use commercially bagged soil. It’s horrendously expensive and is usually no better than local screened topsoil. Gravel: while some marginal plants can squeak by being directly planted in an unfertilized gravel substrate, waterlilies should never be subjected to this indignity unless poor to mediocre plant performance is the objective.

Never plant a waterlily in less volume than a 16”x7” (41cm x 18cm) pocket, bag, or pot. 24”x7” (61cm x 18cm) is even better for large landscape plantings, and requires less frequent maintenance intervals than smaller containers. Full-size lotus require a baseline minimum of a 24” (61cm) diameter container or pocket but they really do superbly with 36” (91cm) for an impressive planting. Soil depth on lotus should be no more than 3” to 4” (8cm to 10cm) regardless of container size. One thing to remember about container size ... they will need to be lifted out of the pond at some point, so keep the size commensurate with your ability to remove it later.

Varieties of waterlilies can make a substantial difference in overall performance. The Laydekeri family of hardy hybrids are always top performers when it comes to a multiplicity of blooms as are some others. Use a knowledgeable grower who can assist you in selecting the best waterlilies for your area. Avoid any hardy cultivar with an “odorata” or “tuberosa” root system if planting in a gravel-bottomed pond or a small container. They are too aggressive and like to run too far too fast. Tropicals will literally overrun the pond when fertilized with Nutricote ... really ...

Fertilizer ... Nutricote

Use the 13x13x13 + minors in a Type 360 day formulation if possible. I’ve been lazy for the last several years, and have just been using a 13x3 with micros in both a 70 and 360 day formulation, as are some of my fellow growers. No doubt this could be dramatically improved upon ... Under the application rates found here, use the “High” “Top Dress” rate for your USDA Agricultural zone. (Gram to volume conversions given below.) One application of Type 360 will last two years at least, in Zones 4-8. I also use this same formulation (13x3) in a Type 70 day release curve and add it to the Type 360 when potting in late summer in Zone 7 because the 70 day formula comes on quicker (7 days) and supplies just enough nutrients for the plants to flush out prior to the end of the growing season ... lasting until spring when the 360 kicks in again and rocks for an entire two seasons or more depending on Zone. 

I’ve always been a fan of the Rich Sacher method of fertilizing which advocates “a heavy hand with fertilizer”. Since Nutricote is so stable in its release, it’s a good one to experiment with in regards to megadoses. When shifting up a 1 gallon (4 liter) hardy waterlily (spring, Zone 7) to a 4 or 5 gallon (15 or 19 liter) waterlily container, I use approximately 2/3 cup of 13x13x13 with minors Type 360 Nutricote, and 5 to 10 each 5 gram aquatic fertilizer tablets. If I were shifting up in the fall, I’d simply skip the tabs. Assuming a US$100 for 50 pound (23 kilo) delivered cost for Nutricote, the cost of fertilizing a 5 gallon (19 liter) waterlily at this application rate for 1 to 2 years with Nutricote would be only 70 cents. This is based on a delivered cost of .0044 per gram buying in 50 pound bags. Consumers buying smaller amounts will pay US$4.97 for a 1 pound (.5 kilo) container of Red Dynamite at Home Depot, which is slightly more than one cent per gram. At 454 grams per pound, 2/3 cup of Nutricote weighs 160 grams, which costs only US$1.70 per application, and will easily last at least one year and likely two or possibly more depending upon zone, etc., etc. ...


1 Teaspoon = 5 Grams
1 Tablespoon = 15 Grams
1 Cup = 240 Grams

The technique for potting with Nutricote is fairly standard as one would expect with just a couple of extras thrown in. If using a plastic pot, wet the bottom first and then throw the fertilizer in and swirl until it’s evenly distributed. The water helps the prills to be less slippery and more inclined to stay put.

The same N. 'Laydekeri Fulgens'
plant as above in a different
location, summer 2009
See large image for cultivation details

If shifting up from a small container add an appropriate number of fertilizer tablets which will give the new potting a really good start. If starting from a bare-root division, skip the tablets if you wish and add some Type 70 or just wait for the Type 360 to kick in about a month.

If using a planting bag, add an inch (2.5cm) or so of soil prior to adding the Nutricote and keep the Nutricote about an inch (2.5cm) away from the edges of the bag. This will help keep the fertilizer from leaching too readily into the pond. Since Nutricote has an extremely stable release curve, it is probably the safest fertilizer to use in an aquatic environ with fish, but it pays to be careful nonetheless.

Since Nutricote will last two full seasons even in the southern USA, the question arises about what to do during the third and possibly fourth years provided the waterlily doesn’t require repotting at that juncture. I just remove the pot from the pond well before I expect to see the first emergent leaves in the spring, place a 6” (15cm) mat of straw on the ground, flip the pot upside down on the straw, coax the soil mass out, rinse the pot, apply some more Nutricote, reseat the soil mass firmly with a couple of shallow drops, and place the container back into the pond. This can also be done just as effectively in the fall, and is quite practical for a homeowner with a traditional pond that uses potted waterlilies.

An alternative, but less effective, method is to take a paper towel and roll a few Nutricote “joints” and twist the ends shut, and use just like fertilizer tablets after first pushing pilot holes with a stick in the soil, and then using the stick to ram the fertilizer to the bottom of the hole. Veterinary gelcaps filled with Nutricote are another alternative to paper towels, if one really can’t seem break the tablet addiction.

This is the cheapest, least labor intensive, and most effective way I’ve found to maintain truly beautiful waterlilies. While a lot more work should be done with formulations for various plants, experimenting with various release durations in different climates etc., this product certainly has a lot to offer for both the professional and hobbyist grower.  

* A prill is a small aggregate of a material, most often a dry sphere, formed from a melted liquid. The material to be prilled must be a solid at room temperature and a low viscosity liquid when melted. Prills are formed by allowing drops of the melted prill substance to congeal or freeze in mid-air after being dripped from the top of a tall prilling tower. Fertilizers (ammonium nitrate, urea, NPK fertilizer) and some detergent powders are commonly manufactured as prills. Wikipedia

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