One of the difficult aspects with growing Zamias is the chore
of cleaning the seeds. Unlike the seed coat of other cycad seeds,
Zamias have a very rubbery seed coat and sticks to the seed. I
have seen hundreds of thousands of seeds being wasted because
people did not have the time or the method to clean them.
In my early years of growing cycads I would only produce 100 seeds
or less at a time. I would watch TV at night scraping the seeds
one at a time with my pocket knife. I had to find a better way
than this. Next, I put the seeds in an empty pot and place that
pot near a fire ant mound. Within a week the ants would pick the
seeds clean. This worked pretty well but the ants wouldn't clean
more than a couple of hundred seeds before they would lose interest.
Dr. Bijan Dehgan, at the University of Florida, told me his favorite
method was using a wire brush on a drill. He instructed me to
put the seeds in a coffee can, cut a hole in the lid, and insert
the wire brush into the drill through the lid so that when it
was placed on the can it would keep any extra material from flying
out when the drill was turned on. This worked very well but I
needed something that would clean 1000s of seeds at a time. I
improved on this method by taking a length of "all thread"
(a metal shaft with threads all the way up and down), and placing
three large wire brushes on the shaft with nuts in between each
brush. I would fill an entire five gallon bucket full of seeds,
add water and a little sand, and scrape the seeds for almost an
hour. I would then use a pressure hose to clean off most of the
residue, but not all seeds were perfectly clean. I have seen other
nurserymen over the years use rock tumblers, cement mixers, and
potato peelers to clean their seeds but they found that many of
the seeds would be damaged. One nurseryman used to nick the seed
coat, place his seeds on a bed of clean sand, cover with a screen,
and pile oak leaves on everything. After a month or so the bugs
and natural enzymes would clean the seeds. Even though it sounded
bizarre, this was the only natural way I had ever heard of.
In 1992 an old groves man told me a story about a product he had
used in the 1950's to separate the seeds from oranges so that
they could be used to plant rootstock material for grafting citrus.
He told me how they would throw massive amounts of oranges in
a large cow trough and then cover the oranges with water. He would
next pour a cup full of a liquid into the trough. In approximately
a week the oranges would break down into pulp, and the seeds would
sink down to the bottom of the trough. The most important aspect
of this method was that the seeds were still viable. I wondered
if something like this would work with cycad seeds. The man didn't
even know how to read and could not give me any clues as to what
this product may have been.
After months of searching (most people didn't even know what I
was asking about) I discovered that product was a pectinase enzyme.
From what I was told the enzyme breaks down the cellular structure
of fruit but wouldn't harm other materials such as seeds or plant
material. In Florida this enzyme is still used to separate the
orange seeds from the fruit in mass quantities. In North Carolina
it has been used to make apple juice. By using the enzyme, more
juice can be produced from each apple because there is no wasted
material, except for the seeds, to throw away. I thought I would
check all this for myself so I procured some enzyme and conducted
a few experiments. I put some Zamia floridana seeds in three different
cups, and put three different strengths of enzyme solution to
test for speed of cleaning. I used 1/2, 1, and 1 1/2 teaspoons
of enzyme per pint of water for the three different cups. After
a week, there was what appeared to be a liquid wax floating on
the top, and after 2 weeks only a few seeds were clean. I assumed
the enzyme was having a hard time penetrating the seed coat. I
tried scraping the seed coat a little for my next experiment.
Eureka! The enzyme entered the scrape and broke down the coat
from underneath. Depending upon the size of the hole the seeds
were perfectly clean in as soon as 5 days using the 1 1/2 teaspoon
rate. All I had to do after that was to rinse them in water and
I had perfectly cleaned seeds. Having to manually scrape each
seeds still took too long. I found that if I soaked the seeds
in a bucket for three days and then used the wire brushes for
a couple of minutes, the seed coats would be damaged enough to
let the enzyme work. For those who don't have a drill, I found
that after the three day period, if I put some gloves on and worked
the seeds through my hands for ten minutes I would get the same
results.
The next question was still critical. How would the use of the
enzyme affect germination? I found that even after soaking seeds
for up to three weeks, I had no loss of germination. I then soaked
some seeds that had recently germinated in the enzyme and after
three days, the radicles weren't adversely affected. I think the
key is that this is a very specific enzyme and does not work like
an acid that could damage seeds.
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New: I have had enough people asking me about this product to make some available. I have a granular form available that is very inexpensive to use. I can clean approximately 40,000 Zamia seeds with $4.00 worth of enzyme. For more information click the link.
