Overwintering Tropicals in the Sunroom
Every now and then a tropical lily doesn't return in the spring.
So, I've learned to overwinter several of my favorite tropicals
in my sunroom, in a bucket. This works easiest with tubers. I
find that water temperatures around 70 F / 21 C work well.
First: Safety! Water and electricity can be dangerous. For
maximum safety, plug all electrical equipment near water into
a socket with a ground-fault circuit interrupter. Unplug all
electrical equipment before reaching into the water. Never remove
a warm heater from the water or it may break instantly. Always
unplug the heater and wait a half hour or more to equilibrate
with the water temperature before removing the heater from the
Location: Select a spot with at least a few hours' direct
sun. Remember, when working with water you will certainly spill
some, so the piano top or an expensive silk rug is probably not
a good spot for a water garden. The warmer the air temperature
stays in your lily spa, the easier it is to keep the water warm.
Materials: Make use of a clean 5-gallon (20-liter) bucket.
I use well-rinsed laundry degergent buckets; they seem sturdier
than paint buckets. Besides, I wash laundry more often than I
repaint my house. The orange buckets sold at the local big-box
home store seem too flimsy to me.
Heater: Use a fully-submersible submersible aquarium heater:
Don't get the design that attaches to the top of an aquarium;
heated water evaporates fast. The heat output you buy depends
on where you place your bucket. A low-watt heater designed for
a 5-gallon / 20 liter tank may only raise the water in your bucket
by 10 degrees F / 5.5 degrees C. If your growing area gets very
cold at night, this will not be warm enough to keep your lilies
happy. My sunroom stays quite warm in the daytime, but often
dips down to 40 F / 4C at night. A heater designed for a 50-gallon
/ 200 liter tank costs only about twice as much as the 5-gallon
heater. I bought one designed for a 50-gallon tank to use in
my 5-gallon bucket.
Extension cord: You might need one.
Thermometer: Ditto. I test the water temperature with my hand.
It should be barely lukewarm, not hot and not cool.
Procedure: Fill the bucket with water and place it where it
receives at least about five hours of direct sun. I think artificial
lighting would work fine, though I don't need it.
Place the heater into the water. Be sure to submerge it completely.
Plug in the heater. Remember to keep all electrical connections
above the water level so water cannot flow down the cord and
wet the electric socket or a cord-to-cord connection. You should
see the heater light come on.
Return after a few hours. Unplug the heater. Check the water
temperature. Do not put your hand into water containing a heater
that is connected to the wall socket. If you are really diligent,
come back at night and re-check the water temperature. Adjust
the heater thermostat as necessary. Regulate the water temperature
before adding your tubers to avoid having cooked tubers.
When you are satisfied with the water temperature, add your
labeled tubers. Just let them float or sink in the water. Use
plastic mesh bags to hold the tubers when I have more than one
variety. This way you can more easily keep them properly labeled.
Your goal is to get them through the winter alive, but not alive
and growing. If they do begin growing, that is not really a problem;
but you probably don't have much room in your bucket. If your
tubers begin to grow, turn down the water temperature a little.Check
the water level every few days. If the water level drops far
enough to expose the heater, it breaks. A submerged, live, broken
heater creates a very dangerous situation.
If you experience a mosquito problem, put a drop of dish soap
in the water. This breaks the surface tension of the water and
the larvae drown. (This works in your tank bromeliads, by the
Change the water every month or so to prevent salt buildup.
Again, be sure to unplug the heater and let it cool down before
removing it from the water.
In the spring, turn up the water temperature bit by bit until
it becomes really warm and the tubers begin sprouting. Nip off
plantlets, pot them into small pots, and let them enjoy a head
start in the bucket before setting them outside. You may see
flowers earlier than usual this way.