Northeastern USA

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Growing Tropical Waterlily Seedlings
in the Basement

 by Louis Belloisy
Morris, Connecticut - Zone 4 ½
Click images to enlarge

Living in the northwest part of Connecticut, my growing season for tropical waterlilies is very short. Blooming season is usually from mid-June until late August. So, I have to get a head start on growing new season cross-pollinated seeds. I do this in the basement with heated water and supplemental lights.

For details about collecting and storing seeds see
Growing Tropical Waterlily Seedlings in The Basement
in WGI ONLINE Journal Volume 1, Number 1.


This is the normal amount of seed harvested from a large seed pod, using the quarter for scale. The pile of seeds is about 1/8 of inch high. Planting of the seeds is done usually the middle of October. It takes about nine months from seed sowing to first bloom. 

Seeds are planted in black plastic transplant trays. The growing tank is a 45-gallon plastic container which is placed on a heavy-duty foot warmer that is used on concrete floors in factories.  

Transplant tray


Foot warmer
White sand is placed in the growing tray with identification tags on each square. I used to sow the seeds randomly in an 8-inch azalea pot but when it came time to transplant the seedlings to individual pots, I always had a hard time trying to separate the roots. Now I grow seedlings in these trays and it works very nicely. I sow about six seeds to a small square and eliminate all but one sturdy seedling. 

The tray with seeds is placed in the tank. Water must be added very slowly so as to not disturb the seeds. 

A light with three 40 watt grow bulbs is added over the top of the tank. This gives proper illumination and coverage 16 hours a day. Water temperature is kept at 85-90°F ( 29-32°C). There is also a stainless aquarium heater for backup in case the mat heater should fail. I have had the mats for about five years with no failure. I also use one to bottom-heat a small tank in the greenhouse for growing out the seedlings.

It usually takes about 10 days until I see the first sprout. Seedlings may have only rosette (underwater) leaves for up to one month before plants send up the first floating pad. At this point, I mildly fertilize, using a syringe and a #12 needle. I inject a small amount of a water-soluble fertilizer into the sand under the roots. I try to keep the growth slow so as to not overwhelm the tank and keep the water clear. Seedlings are then transplanted into 4-inch pots to start their grow-out and, in the middle of March, they are moved to a temporary growing tank in my small sunroom. They stay there until the middle of June, when they are moved outside.
This is the temporary tank, minus the liner, set up in the sunroom. Note the three foot warming mats at the bottom of the tank. These pads will keep the water at 80°F (27°C) when the outside temperature is freezing or below. There is minimal heat in the sunroom, so most of the heat comes from the pads.

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