There are containers designed for pond plants made of plastic and the sides and bottoms have small holes to let the pond water in and the roots escape but not big enough to let the planting medium escape. You get these special containers at a garden supply center that sells pond products or you can go online and get 'em that way (don't like the shipping costs so I buy at a garden center). Lillies and Lotus plants are deep water plants and Cattails and Rushes are marginal or very shallow water plants. I have 5 Cattail plants started in a 9 in. square container, filled within 1 in. of the top with medium and thumbnail sized rocks that I collected on a nearby Lake Michigan beach on top of the medium. Also inserted 2 fertilizer tabs 3 in. deep and not to near the plant bulbs. Have 4 Helvola Lillies started in 2 seperate 6 in. square containers with the same medium/rock/fertilizer setup. The rocks are for weight and for looks. These plants are in the basement 265 gal. pond until they grow larger and it gets warmer outside. The turtles are all outside so I kicked the pond temp up to 80 and am using a 160 watt UVB/UVA mercury vapor bulb on a timer for sunlight. Also, floating in the water and staying out of the frosty nights are a dozen Water Hyacinth and 6 large Water Lettuce plants. The cold nights will kill the leaves so that's why they are in the house.
I have growing in the outside pond right now, in a 6 in. square shallow container, 3 clumps of Blue Rush and in the other end, on the bottom is a 20 in. kidney shaped container planted with Helvola Lillys. The Helvolas have 3 to 4 in. pads and produce little bell-shaped flowers all summer long. All the water plants grow large root systems , therefore that type of container is necessary as the roots can grow through the sides and bottom. The floaters spred like crazy and the extra ones can be plowed into your veggie garden as mulch. They are so beneficial in the pond as they use up nitrogen that could grow algae and shade the pond which inhibits algae growth. Can't have too many--excellant turtle food also.
George
