Tropical Fish Hobbyist - October 2010

a few minutes. Then I place them, pot and all, in a hard foam fish-shipping box lined with newspaper. A standard shipping box can fit four 7-inch square or round mesh plastic pond pots. I then place the box in my unheated garage for winter.

SHALLOW-WATER (EMERSED) PLANTS

Emersed plants, together with floating water hyacinth, are the workhorses of the summer pond or tub. Their profuse growth, thick rhizomes, and thick root system are powerful filters for the fish pool or tub. Nearly all of them do well as marginals also and generally can tolerate submersion from 3 to 6 inches above their crown. Some can be planted in deeper water and are extremely useful for tubs or ponds without shelving, such as giant cattail (which can be planted with up to 24 inches of water depth over its crown), graceful cattail and pickerel (to 18 inches), and yellow flag iris (to 12 inches).

Shallow-water plants can be boxed up like marginals or placed in their pot without any trimming at the bottom of a pond or tub so long as it is deep enough or kept in a warm-enough area where there is no chance it will freeze solid. Some folks place the tub in their basement or garage for overwintering after the foliage drops off. When they begin to show growth in the spring, keep them at their maximum depth until the last frost date in your area (contact your county’s Cooperative

A 70-gallon stock tub pond with a tropical night-blooming water lily, pickerel, and water lettuce.

Extension office), when you can then raise them to the water level of your choosing.

You may notice offshoot rhizomes growing outside your pot when you remove them for winter—pickerel and iris are notable for this. Simply snap these off and place them in a fish bag with a large heaping spoonful of peat moss. Shake, tie off, and store them away in the fish box with your marginals. But do not, under any circumstance, divide or re-pot your plants in the late summer or fall. They need time to recover and grow before dormancy and storage. If not, they often rot.

Come spring, you will discover that most of your boxed and bagged plants will be growing foliage! Though it will be white in color due to the lack of light, it’s still a nice surprise for the water gardener that I look forward to every year.

By the beginning of autumn, the cattails have browned and gone dormant and the pickerel foliage is dying off, but the forget-me-not is thriving in the cooler weather.

TRUE AQUATIC (SUBMERGED) PLANTS

Although aquatic plants’ reputation as oxygenators is exaggerated to this day in pond circles, these plants do create spawning sites, help with water quality, provide protection, and are a medium for nutritious microorganisms to grow upon. They also are the first to be covered in algae, as most are finely leaved. I generally only use true aquatics if there is a need of spawning sites for egglayers, such as barbs (and even here, water hyacinth works just as well).

Most of our popular aquarium plants also fall under this category, such as the Amazon swords, Cryptocoryne, and a host of stem plants—but as tropicals rather than hardies.

In a pond or tub, if shallow enough, they will grow emersed leaves and flower above the water line, but they will need to be discarded or relocated to an indoor aquarium for the fall to spring, at which time they will drop their emersed foliage and grow their submersed leaves again. Don’t be alarmed and think your plant is dying if you witness this!

Hardy aquatics include native hornwort, Bacopa, some Vallisneria species, and Ludwigia. I generally bring true aquatics indoors to an aquarium—pot and all (I usually use the 4-inch mini pond pots)—or purchase new ones each season. Potted or lead-weighted arrangements generally do not survive winter submerged in a tub, let alone boxed, but it does happen from time to time for me.

But the most celebrated of all the true aquatic plants, indeed of all pond plants, are the water lilies. Hardies and tropicals must be overwintered very differently.

When the weather starts to turn cold, hardy water lilies form indicator leaves, which stay small and near the substrate. These assist in photosynthesis during the winter, but they also signal the water lily when spring has arrived. Do not remove the indicator leaves! Even if you box up your lily following the same method I outlined for marginals, do not prune away the indicator leaves.

I get better results with my hardy water lilies when I store them submerged over winter, however. Again, this can be done in a tub or pond that does not freeze below the pot level, or in a garage or basement tub or bucket after the floating pads die off.