I doubt that freezing the duckweed will work. As it goes into cold weather duckweed and a number of other water plants form Turions that sink to the bottom and overwinter in the relative safety of the mud. In spring these dormant bulb like structures refloat and the plant's life goes on.

Freezing the duckweed in the freezer is likely to result in a situation similar to freezing lettuce...not too pretty.

I wondered if there was any chance of wintering over my water hyacinths but was told that they would not survive over the winter. Do you have any experience with this type of aquatic plant. I live in NJ and it is my first year dealing with plant material for the pond.

Also, should I keep the plants on the shelf or must I lower the waterlilies, iris, pickerel rush,etc to the bottom? The pond is two feet deep.

Vickster

Vickster, You are hijacking this post, you should have started a new one, or better yet found the information by a forum search. However I am irresponsible so I will answer your question for you. Water hyacinth cannot take a freeze, you have to take it indoors, but that gives you an excuse to set up a big fishtank now doesn't it. Depending you your waterlilies species they may have to be brought inside too, but its best if you lower all the plants down into the pond, its the aquatic equivalent to mulching and it helps winter survival rates. The liquid water in the bottom of your pond stays at 40 F all winter long, so long as it stays liquid.

As for the OP, I'll bet you would get a green mush out of the freezer bag when you were done, unless you have a tropical species its more likely to survive if left to naturally go dormant in one of the containers that you grow it in I would imagine. Good luck.

In the fall do this: Take a 5 gallon bucket, put in dechlorinated water (get dechlorinator from a pet shop), fill to 1 inch from top. Add 1 or 2 water snails, put in duckweed. Put a regular light 12 inches from the water surface, use a timer to have the light on 14 hours each day. Change 50% of the water each month. The snails will provide nitrates for the duckweed to feed on and it will survive the winter.

Remove snails if they get too many. They will feed on the algae that grows in there. Do not feed them anything else.

This is how I grow snails as fish food, but the duckweed does just fine too.

NOTE: Duckweed seems to need more light than algae does in my fish tanks, so when I turn the light down to 10 hrs per day, the duckweed seems to slowly die back. So keep the light (any light, about 60 watts regular bulb or equivalent in flourescent, does not have to be a special plant bulb. However a special plant bulb will likely make the duckweed REALLY grow fast.)

Water plants also need micronutrients to do really well, and this includes duckweed. The Big 3 are not enough. Although duckweed is tough, it is not indestructible.