I want to start planting water lilies and lotuses in my pond but I'm not sure when exactly would be the best time to do that. I am zone 6b and the last frost will be the end of May but can I start planting now because the water will no longer freeze?
Also, the bottom of the pond is natural and there is a thick mat of growth/weeds dense enough to walk on. I dragged much of that out when digging out the pond but I am concerned that it might eventually strangle my lilies/lotuses. Can I plant the bulbs directly in the soil or do I need to plant them in a container?

Hello .. I have a few ponds with fish in Oregon zone 6b for over 25 years. I can suggest hardy water lilies, hardy water iris, winter mint, lizards tail, arrowhead plant and marsh marigold. There are much more These all over winter in the pond good to zones 3-4.

Much of the water cover plants like pickerel, taro, cardinal flower and water lettuce I plant after the water temps are maintained at 60 degrees. Most of the cold hardy plants are available now at nurseries and the non hardy plants like taro mosaic plant will be available after may or generally after the temps are warmer.

Every plant in the pond needs to have a purpose – whether it is color or height, or to deter algae growth. Using a variety of water plants can add visual interest as well as keep your water garden healthy. If they are hardy plants are so easy. Perennial water plants can also save you money in the long run. Visit some of the many pond plant online available for ponds. Get what you can now keep inside while temps warm up then you 'll have exactly what you need.

Thank you so much for the response and the suggestions! I want lilies and lotuses for some water cover/protection for my koi and goldfish from birds. I notice you do not have hardy lotuses on your list, is it because you have had problems with them?
I can't wait until the water is 60 degrees because it never warms up to that temp. It is about 20,000 gallons and 6 ft deep at the deepest point so it stays consistently around 50 degrees.
Do you have any websites that you trust to get pond plants from?

There are several on line places to get hardy lotuses, which is not to say they are cold water lotuses. There is a native, cold water lotus available at Hughes water garden in Wilsonville, but it does not at all look like what one images when one says "lotus."

If your pond never reaches above 60, growing lotus is a waste of time.

Here in Oregon, it is not the winter that kills lotus, it is the summer. We typically do not get enough heat, nor do we get enough sunlight.

If you have a place indoors that has both heat and light, you could try bowl lotus. Lotus has a very short mail ordering window of opportunity. It must be kept in cold storage until it is ready to ship, then it must be warmed up immediately upon arrival. Shipping is April - May - maybe June, depending on zone. You can order now, but you won't get it until next year.

If you tell me what it is you like about lotus, and why it is so important to you, I might be able to suggest something else.