Waterlily Soils, Fertilizers, and
by Rich Sacher, New Orleans, Louisiana
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It does not matter if we are hobbyists or commercial growers;
we all want to know what is the perfect soil, pot and fertilizer
for achieving the best results in growing waterlilies. The question
is simple, but not the answers. We need explanations here. Once
we understand the underlying principles involved, I am confident
that anyone can successfully grow beautiful waterlilies in almost
any soil, with nearly any fertilizer, and in almost any kind
The Perfect Soil
beautifully grown in "spillway sand",
a pot with holes,
and top-dressed with
Many books and articles on growing waterlilies state that
clay soil works best for the purpose, but that is rather vague.
What does "clay" soil mean? Is it 20% clay? 50% clay?
If your local soil is not much more than beach sand, what are
you supposed to do? And what is so special about "clay"
The recommendation for using soil that contains clay comes
from the fact that clay particles serve as a colloidal sponge,
adsorbing and holding onto dissolved nutrients until the lily
roots access them. In extremely sandy soil, added nutrients quickly
dissolve and migrate out of the sand into the water. There they
only feed algae, not the waterlily. Clay in soil helps to slow
the loss of fertilizer to the water, keeping it in the soil pot
where the roots access it.
Older books on water gardening often give a formula for waterlily
planting that includes bone meal, composted sod, horse manure
and some topsoil. This combination provides for slow release
of nutrients from the bone meal and manure, with sod serving
as the organic sponge that holds onto the nutrients a while so
they do not migrate too quickly out of the soil.
Since most of us do not live on farms with available sod and
horse manure, we obviously need other options for waterlily soils
and fertilizers. These days, we have lots to choose from!
When I was a teenager, I grew waterlilies successfully in pure
masonry sand . . . sand so devoid of any clay or organic matter
that it had no nutrients of its own. In fact, workers mixed this
same sand with cement to pour a concrete walkway; after forty-five
years, that walkway is still in fine shape! I knew that this
"soil" needed lots of fertilizer on a regular basis.
So I used a teaspoon (5 milliliters) of granular fertilizer and
inserted it into holes in the sand that I made with a stick.
I did this every two weeks during the growing season, and it
produced great results. At the time, no one sold fertilizer tablets
for water gardening . . . or, if they did, I was not aware of
them. So, yes, you can grow waterlilies in pure sand as long
as you maintain fertility.
Today I use what we locally call spillway sand, which
the Mississippi River deposits as it passes through the Bonnet
Carre spillway, a flood control project west of New Orleans.
Although very sandy, it does have some fine silt and clay in
it, perhaps 10%.
To pot up lilies for the nursery, I put a handful of peat moss
in a ten-inch (24-cm) diameter pot (to provide organic matter).
Next, I add a handful (0.25 cup [0.6 liter]) of cheap, very coarse
chemical fertilizer (this year, 14-14-14). After that, I fill
the pot with spillway sand and mix everything thoroughly. Then
I plant the lilies, either transplanting them from smaller pots,
or planting them as bare root plants. Because my soil is so sandy,
(the peat moss helps, but is not a perfect solution), beginning
three weeks later, I apply a supplemental fertilizer tablet every
two weeks during the growing season.
If you have soil with some clay in it, omit the peat moss
(or not), and use the same amount of coarse fertilizer as above.
Then perhaps fertilize your ten-inch (24-cm) potted hardy waterlilies
with one tablet every three weeks (instead of every two weeks)
during the growing season. Because tropical waterlilies grow
at such a rapid rate once the temperatures are warm, I give them
slightly more fertilizer than hardies.
Any soil you dig from your property is probably just fine for
waterlilies, as long as it does not include lots of bark, mulch,
leaves, pesticides, or floating materials. After all, the fertility
of your local soil is not an issue when you add granular fertilizer
at planting time, and then add fertilizer tablets at regular
Ironically, your own soil may be quite superior to so-called
"topsoil" sold prepackaged in bags at nurseries. These
soils often have finely chopped bark and peat moss mixed through
them, making them great for flower beds and potted plants, but
unsuitable for waterlilies. Sometimes "topsoil" mixes
contain so much buoyant organic matter that the soil floats out
of the submerged pot. Additionally, the pH may be too low; or
the soil structure may be too loose to hold the waterlily in
I certainly do not want to minimize the value of soils that
have some clay or organic matter in them. They do help to regulate
the rate at which added fertilizers dissolve and migrate into
the pond water. However, such ideal soils are not necessary for
spectacular results. No single, magic, ideal soil exists that
is required to grow beautiful waterlilies. For most people, whatever
soil they dig up from their property can become quite suitable
for growing waterlilies.
However, if your native soil is so full of clay that you can
spread it with a butter knife when it is wet, and you can throw
a pot or make sun dried bricks out of it, you should probably
mix your clay soil with sand (half and half works) before using
it for lilies. Otherwise, the soil may be too dense for the roots
and oxygen to penetrate it effectively.
The bottom line on soil for waterlilies: use mostly sand or
good topsoil containing some clay, but keep it free of floating
materials. It must be heavy enough to sink quickly when wet,
and not float out of the pot. It does not need to be especially
fertile. In fact, it need not be soil at all! It could be masonry
sand, or a ceramic-based cat litter. The main requirements are
that it be heavy and firm enough to hold a newly planted waterlily
in place. If it can hold onto dissolving fertilizer, too, so
much the better.
The Best Fertilizer
When you grow waterlilies in pots, they depend on whatever
nutrients exist within their planting container. The pot confines
all their roots. I mix granular fertilizer into the soil when
planting or transplanting a waterlily. As mentioned before, I
use a cheap, coarse, general-purpose fertilizer packaged in 40-pound
(18 kilo-) bags. Sometimes I use 8-8-8; last year I used 13-13-13;
this year, it happens to be 14-14-14. Once, I could find only
10-6-4. All of them work just fine. The overall texture of this
cheap fertilizer is coarse, but I detect some fine fertilizer
dust, too. Fine dust makes for a quick release of nutrients,
while the coarse particles take many weeks to dissolve completely.
Although we can make an educated guess as to what fertilizer
formulation works best for waterlilies, I really do not know
what the perfect fertilizer might be. I do not think anyone else
The numbers given on a bag of fertilizer refer to the percentage
of nitrogen, phosphorous and potassium in the mix. Since nitrogen
promotes leaf growth, you might think that 10-6-4 would make
many waterlily leaves, and few flowers. That certainly could
be the case with some terrestrial plants. For terrestrial plants
where we want to encourage blooming, we prefer a fertilizer with
low nitrogen, high phosphorus and low potassium, like 5-20-5.
However, that rule does not seem to apply to waterlilies.
This is good news, since you may use whatever fertilizer you
have on hand. Except for completely water-soluble fertilizers,
which dissolve and migrate into the pond water too quickly, almost
any granular fertilizer may be all right for mixing with your
soil. I do not have experience with pelleted, slow release fertilizers
like Osmocote. Since they depend on moisture to release their
nutrients, I cannot recommend them for mixing with waterlily
soil. I suspect they release their nutrients more quickly in
water (and not last as long as expected) than they do in soil
when they are applied to terrestrial plants. Nevertheless, you
know what? If that were all I had at hand, and I needed to transplant
some lilies right away, I would use it!
We have discussed mixing fertilizer into the soil prior to planting
the waterlily. Now we need to think about supplemental feeding
after the plant has been growing for a few weeks. The warmer
your climate, and the longer your growing season, the longer
you need to feed your lilies. I use tablets with a 10-26-10 formulation.
I put one tablet every two weeks in a ten-inch (24-cm) pot. For
a sixteen-inch (41 cm) pot, I use three tablets every two weeks.
The bigger the pot, the more tablets I use. A Victoria
in a two-foot (0.6- meter) by three-foot (0.9-meter) tub may
require fifteen tablets every two weeks!
Since many roots gather around the outer edges of a pot, I
like to push tablets into the soil about an inch (2.5 cm) or
so from the edge of the pot; this avoids breaking the roots.
I push the tablet in to a depth of about two inches (5 cm), and
then pinch the hole closed. If the plant has become very root
bound, consider using a dowel to make a hole in the soil, and
then insert the tablet.
Okay, let's say you live in a small town and no one stocks
fertilizer tablets. What do you do? If you must transplant and
fertilize immediately, and cannot wait for a mail order shipment
of tablets, you could lift the lily out of the water, make a
hole in the soil, and pour a teaspoon (5 milliliters) of granular
fertilizer into the hole. Pinch the hole closed. Fish LOVE to
dig up fertilizer. Pinching the hole closed, or putting a rock
over it, prevents them from feasting on this treat. And no, it
does not hurt them if they eat some of it.
As I mentioned, many years ago it was customary to put granular
fertilizer into a roll of cloth or paper and insert it into the
soil. There it slowly dissolved and fed the lily. In the days
before waterlily fertilizer tablets were available, I used tree
spike fertilizer for supplemental feedings. I hit the six-inch
(15-cm) spike with a hammer, broke it into four pieces, and pushed
a piece into the soil. This way I made my own tablets that worked
just fine. Still do.
Not all fertilizer spikes are equal, however. Obviously, a
tiny fertilizer spike meant for African violets is not big enough
or potent enough to have significant effect on your waterlily.
The amount of fertilizer used for each supplemental feeding in
a ten-inch (24-cm) pot should be about a teaspoon (5 milliliters)
to a full tablespoon (15 milliliters) if measured in granular
So, what is the underlying fertilizing principle here? It
is this: Never let your lily run out of nutrients. Feed it whatever
you have rather than let it go hungry. Once a waterlily shows
signs of starvation, it could take two or three weeks to reverse
the process with a new application of fertilizer. Meanwhile,
it may cease blooming. Better to maintain high levels of steady
fertilizing so the lily grows constantly, rather than wait until
a drop in flower production or yellowing leaves finally remind
you that you have fallen down on the job!
Top-dressing refers to applying fertilizer to the soil surface
rather than mixing it into the soil. We can fertilize a crop
of corn or tomatoes by sprinkling fertilizer between the rows.
Then we water the soil to begin the process of releasing the
nutrients. We place the fertilizer a few inches (1 inch = 2.54
cm) from the plant stems so we do not burn them with fertilizer.
I do not know if I am the only one who does this with waterlilies,
and there are some precautions to take. Nevertheless, you may
find this same practice useful for fertilizing waterlilies in
For example, I once had a Victoria at our zoo. It was
not growing as large as it should despite having good soil with
plenty of fertilizer in it. However, the leaves were only three
feet (0.9 meter) across, and it had remained that way for almost
a month. In the trunk of my car, I had some Scott's Turfbuilder,
which is very high in nitrogen. (29-3-4). I took two measuring
cups (0.5 liter) of Turfbuilder and poured it into the water,
right above the crown of the plant. "Grow or die!"
I said. I really expected that the Victoria would burn
and die from so much fertilizer. Instead, it grew. Wow, did it
grow! What a revelation that was.
I am not recommending that we all run out and pour
fertilizer on the waterlily crowns. Nevertheless, I find that
when I have hundreds of waterlilies that need supplemental feeding,
it is much quicker and easier to release granular fertilizer
under water, on top of the soil in the pot, while avoiding getting
too much in the center of the plant. When plants are too numerous,
or the lily is too root bound to easily push tablets into the
soil, top-dressing with fertilizer works just fine.
Keep these two cautions in mind. First, if you top-dress a
very young plant, you may kill it. Reserve top-dressing for mature
plants in very active growth. Second, ample loose fertilizer
on the soil means that the water may quickly turn green as algae
multiply in response to increased nutrients in the water.
I dye the water black in display ponds where I top-dress lilies
with fertilizer, so I do not worry about green water. In my growing
ponds, which are not on display, I do not care if the water turns
green. (And neither do the lilies!)
To this day, I top-dress Victorias for supplemental
feeding. For each feeding, I use whatever coarse fertilizer I
have at hand, and use about a cupful for a pot that is two feet
(0.6 meter) by three feet (0.9 meter) and eight inches (20 cm)
deep. I pour the fertilizer in a circle, all around the center
of the plant. This saves me all the cuts and punctures that I
would otherwise suffer if I attempted to push tablets through
a Victoria's minefield of thorns. Otherwise, it always
bites the hand that feeds it!
for display ponds
Another candidate for topdressing is tropical lilies that
have overgrown their pots late in the season. They may be too
large or too heavy to repot into something bigger, but top feeding
with granular fertilizer keeps them growing strongly, even when
badly pot bound. On occasion, I add an inch (2.5 cm) or two (5
cm) of fresh soil on top of the roots after fertilizing, to supply
more room for new root development. This method saves a lot of
labor, and nicely sustains a pot-bound tropical waterlily to
the end of the growing season.
One problem that may arise late in the season is that a lily
becomes large and buoyant enough to float off the pond bottom,
even though it remains well rooted in its pot. In this case,
I tie a short piece of rope between two concrete blocks, place
the blocks on each side of the lily pot, and let go. The weight
of the blocks holds any floater in place on the pond bottom for
the rest of the season!
The Ideal Pots
The ideal waterlily pot should be two or three times as wide
as it is deep. Waterlilies prefer to send their roots out horizontally,
rather than vertically. Having said that, we still sell all our
lilies in pots that are ten inches (24 cm) in diameter and eight
inches (20 cm) deep. The weight of the potted lily is a consideration,
since customers should be able to handle them without undue strain.
This size pot is large enough to keep the lily growing throughout
our seven-month season, assuming you feed it every two weeks.
However, I believe the lily would be happier in the same amount
of soil if the pot were six inches (15 cm) deep and 14-16 inches
(36-41 cm) in diameter.
Most plastic pots sold in the industry for waterlilies are
deficient because they:
1. are too narrow and too deep
2. have no holes in the sides near the bottom
Perforate the sides of your pots near the bottom allows for
water circulation. More importantly, this enables oxygen circulation
at the bottom of the pot. Pots with slits or small holes near
the bottom allow lily roots to grow right to the pot bottom,
and remain healthy all season long. Without these holes, the
roots that first reach the pot bottom eventually die and rot,
creating a three- or four-inch (8- or 10-cm) layer of useless
soil. This is because of the anaerobic (no oxygen) conditions
in the soil at the pot bottom cause this uselessness. The dead
zone slows or stunts the lily's growth. You can prevent this
by making five to six slits in the sides of the pot, near the
bottom. Unfortunately, our industry produces waterlily pots with
no holes in them; maybe everyone is afraid some soil might drift
out and dirty our ponds. The pots do not need round holes; small
slits do the job.
I use a large knife to make stab holes in every lily pot before
using it. The improved performance by the lilies is easy to see.
Even in pots measuring 16 inches (41 cm) in diameter and seven
inches (18 cm) deep (close to my "ideal" ratio for
diameter and depth), I slice holes in the sides of the pot near
the bottom. Interestingly, I never see any soil coming out of
these holes. They are one-inch (2.5 cm) long, narrow slits; they
allow water circulation into the root system without allowing
soil to ooze out into the pond.
Remember, with perforated sides on waterlily pots, you will
grow happier lilies. They will use all the soil in the
pot instead of confining their roots to the better-aerated top
six inches (15 cm) of soil. Perhaps the industry will eventually
catch up with us, and produce pre-perforated lily pots. You can
always find uses for pots with no holes, however. For instance,
lotus and bog plants grow happily above ground in pots without
holes rather than submerged in the pond. Nevertheless, for waterlilies,
the recommended holes make a big difference in improved performance.
I hope that these observations, gained from many years of splashing
around in lily ponds, will help you to become even more successful
and satisfied while growing these gems of the pond, the lovely