Growing Tropical-Aquatic Plants
Master Gardener Paul James adds a variety of tropical and hardy plants to his water garden.
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The latest additions to master gardener Paul James' water garden include tropical plants that will be treated as annuals and hardy plants that will over-winter.
Paul recommends reading plant tags carefully and getting to know the plants' preferred habitats and growing conditions. Some aquatic plants prefer to grow in still water while others prefer moving water. Some plants enjoy shallow water; others can be planted in water a couple of feet deep, while still others just like to float on the surface.
Papyrus plants are at home in still water, so Paul decides to plant them in pockets or bogs adjacent to the pond. There are six such bogs--four in the stream and two adjacent to the pond. At the time of construction, the bogs were back-filled with river rock that Paul now removes to make a planting hole. With that done, Paul removes the plant from its container, places the plant in the hole and replaces the river rock around the base to stabilize the plant. He repeats the same process for the remaining papyrus.
"I have two different papyrus plants growing here, although they look remarkably the similar," he says. One is a Mexican papyrus and the other is Egyptian; both are tropical and grow to about eight feet tall.
Umbrella palms (Cyperus alternifolius) look somewhat familiar to papyrus, but they don't grow as tall. In fact, the dwarf form grows to only two feet tall and loves to be planted in moving water. Paul plants the umbrella palms in flowing water using the same planting technique. The umbrella palms soften the look of the stone edging around the pond.
Another lovely grassy plant is this star grass, and it too prefers shallow water. "I just love the white bracts that form at the tips of the stems, and they last all summer long," says Paul.
Continuing with the grassy theme, Paul selects two types of cattails for his water garden. The solid form known as 'Graceful' grows to about four feet tall and is hardy to USDA Zone 3.
The variegated form,'Variegata', is slightly taller and just as hardy, and it also tolerates more shade.
The Louisiana iris, which thrives in water or boggy sites, is hardy to Zone 4. This version, 'White Moon', should produce white flowers within a few weeks.
Across the stream, Paul plants a colocasia near the umbrella palm. Colocasia or taro is related to the more familiar elephant's ear and grows well in water gardens. 'Illustris' will grow to a height of about three feet.
Along the stream he plants lizard's tail (Saururus cernuus)--in this case, a red-stemmed variety. Lizard's tail is a North American native that's hardy to Zone 4.
Next he adds three Ruella 'Bluebell'. Hardy to Zone 8, they won't survive the winter in Paul's garden, but they'll do fine until fall arrives.
For some low-growing specimens, Paul plants a water mint, a true mint that thrives in water and can spread just as fast as the terrestrial variety. "A number of aquatic plants do have a tendency to spread, often to the point of being invasive," he says.
If you want to add a plant like this to your water garden, be prepared to keep its growth in check or consider using a floater as an alternative. Just place the container-grown plants in the pre-cut holes of the floating island, pots and all.
In this case, Paul plants four variegated pennywort and some water celery. He launches the island into the pond, and in time the plants will spread to cover the edge of the exposed foam but not much beyond the edge of the island, especially if you have koi fish that love to nibble on foliage and roots.
Among water plants that have a tendency to spread, the water hyacinth is perhaps the most notorious. If allowed to escape into a nearby body of water, it can quickly take over. As a result, its sale is outlawed in many states. "However, it's not a real threat here, so I'm going to complete my planting scheme by adding a few clumps," says Paul.
In addition to simply looking good, aquatic plants help keep the water clean because they're great natural or biological filters. "And they complement the nearby terrestrial plants that surround the outer edges of the pond and stream," Paul says.
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