It is not necessary to bring Hardy Water Lilies and Lotus inside, unless the pond is likely to freeze solid, including the roots. For over-wintering, the goal is to keep roots alive until spring.
Don’t expect to keep lotus or water lilies actively growing throughout the winter. They actually need a winter’s rest. Dormancy is their natural way of getting through it. What a great way to handle it – wake up to springtime every year.
Here are a few ways to keep some healthy roots over until spring:
Package the roots.
Over-winter the entire plant in the original pots:
Lift the containers from the pond and leave the plants in the pot. Trim off all dead leaves and stems place the pots in a watertight tub in a basement, or other storage area
Over-winter some or all of the roots (this can be a space saving method):
Remove from pond and original pot, then take the desired amount of roots (rhizomes) Place them inside plastic bags containing a dampened, moisture retentive medium, such as coconut coir, and store. Check periodically to make sure the roots are kept moist.
Storage conditions.
Whether stored in a basement, crawlspace, shed, or spare room, they must be kept cool, dark and damp. Optimum temperature range is 33-50 degrees F, which allows them to stay dormant without freezing.
Put them on a strict, no fertilizers diet – they will appreciate it, come spring.