Easy to grow and here’s how to overwinter water lettuce
Water Lettuce( Pistia stratiodes)is a tender zone 9 tropical that grows in a similar manner to a hyacinth.
The trailing roots function in much the same way as a fish food and fish haven. The major difference is that the lettuce doesn’t flower and will grow more successfully in part shade. The velvety blue-green leaves are quite attractive.
You’ll sometimes see huge specimens for sale at garden shops. Don’t pay more for these as they are simply either mother plants or those formed under high light intensity. Your mature plants will easily reach this size in mid-summer.
Overwintering
These can be easier than water hyacinths but will still stretch out in too-low light levels.
Provide 72F water and a full 12 hours of sunlight (grow lamps) a day to keep them alive.
The odds are the leaves will stretch out and become very ugly. Relax. As long as they’re alive in the spring when the water warms up enough for them, you can divide and use the babies to start fresh with short bushy plants.
Cutting them down — reducing the height of the leaves by half — works nicely.
Propagation
Propagation in the spring (or anytime) is by division. Simple rip the baby (that has roots) away from the mother plant and float it freely by itself.
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Problems
Note that mature fish love to eat the roots of this plant and consider it a bit of a delicacy.
And as the picture shows, yellowing outer or more mature leaves are not uncommon, particularly in colder water or cool nights. See below.
Sometimes in low light or cold water, the plant will start to rot. Remove the rotting sections and refloat (but do correct the water temperature or light levels if you want to see improvements.
This is more a problem indoors, while growing this plant in the shade or at the shoulder fall and spring seasons.