When I was running the nursery, we had several different display lotus plants and some for my own gardens that all needed to be overwintered. Our ponds were too shallow to trust leaving them so I worked out other means. Here are your options:
Overwintering lotus isn’t all that difficult if you live in a zone 4-5 garden.
You just leave them in the garden (assuming they are growing in the soil) and they are usually quite hardy.
Colder gardens need to follow some of the instructions below.
Container Grown Lotus
If you are concerned about them or you are growing them in pots, try these techniques.
If your pond doesn’t freeze solid. After the top growth has been lightly frosted and the plant is dormant, cut back the foliage to pot level and put the pot into the deepest part of the pond. It will overwinter there.
In the spring, return it to its regular position in the shallow section of your pond.
If your pond is shallow (and freezes solid) or if you’re growing a lotus in a container then your objective is to keep it cool and dormant without
freezing it solid.
With container grown plants, I’ve overwintered lotus by leaving them in their containers and setting that container into a shallow tub in a cold area where the temperatures did not go below freezing (or if they did, they thawed out immediately) or did not get above 45F (this would force them into growth)
The odd bit of freezing normally won’t hurt them if they are dormant; the bigger problem is in cycles of freezing and thawing (turns them a little mushy). So a steady, cool temperature is ideal. Think cold cellar or attached garage that doesn’t freeze solid – that kind of place.
You also do not want to let them dry right out – hence sitting the tub in a shallow pan of water. The soil will be damp constantly.
I’ve also successfully overwintered them by putting them in an old freezer out in the barn, filling the freezer with water, putting a stock tank heating element (you can purchase these as pond heaters) into the freezer and shutting the lid. The thermostat on the heater stopped the water from freezing solid and the lotus survived.
The one year we got a power outage and the freezer froze solid was the year I lost all the plants in the freezer. It also produced a very powerful fragrance in the spring when it thawed out. I don’t recommend freezing your overwintering lotus plants.
Those are the three easy ways to overwinter lotus. You can find other articles about backyard ponds right here.
You can find both lotus plants and seeds here.