Eliminating green waterHouttuynia - which as near as I can figure out is pronounced how-too-in-ee-uh - is a wonderful plant, a beautiful plant It is sometimes called the chameleon plant, but so are a dozen other better behaved plants, so look at the small print. Houttuynia has gorgeous leaves in green and red and yellow and is irresistible in a catalog photo or a nursery bench. Don't ever - I mean DON't EVER plant this in your garden.

I did. Many years ago. I'm still trying to pull it out, dozens of yards from where I planted it. The roots dive to the center of the earth and come back up where you least want them.

On the other hand, this is a great plant in pots for a small LINED water garden, someplace where the roots cannot escape. There is a lesson to be learned from this.

The lesson is that many plants we think of as garden plants are quite happy in a water garden. More important, bought as garden plants they are a fraction of the price of plants sold in pond stores as aquatics.

How many of you are plagued with green water? Let's see hands. Thought so. OK. how many have spent money on devices that kill the algae, including filters you have to clean out all too often? Yuck.

You don't need them. The problem is that you don't have enough plants. Fish or fertilizers release nitrogen into the water. Nitrogen and sunshine cause the green algae to thrive. Green water. But water plants suck up the nitrogen and shade the surface, and the water clears. No equipment, no messy chores.

Japanese iris are great nitrogen suckers. If you have some in the ground or can find them at a garden center (at a late season mark down), you can plant them in your water garden now. But they will need repotting.

The reason is that potting soil or well amended, good garden soil has humus, organic matter, and that's a good thing. Usually. But humus floats. Put a pot with good soil in your pool and the humus will work its way out and litter the water surface.

You need to repot them in plain old dirt. For a good gardener, that can be hard to find, certainly not in YOUR garden. Cheap bags sold as "topsoil" - not the pricey name brand stuff but the buck a bag product - is usually pure "dirt". Or you can steal a trowel or two from a less committed neighbors' garden after the sun goes down.

Water garden books tell you to use pots without holes. That's wrong, at least for ponds with liners. A regular plastic nursery container with holes in the bottom lets the roots wander out to get that excess nitrogen.

Canna lilies (which like so many "lilies" are not lilies at all) are fine pond plants. You can buy tubers in spring for three or four bucks. The same thing growing in a display pool in a pond store will cost you fifteen.

Unfortunately they are not as easy as iris to move mid-season. Fortunately they multiply. If you have cannas planted in a patio tub or in the ground, let the first frost kill the tops, dig, and store the tubers dry and cool. They're easier than dahlias. Next spring you'll have enough to put back in your patio tub and in the pond as well.

The huge leaves of green elephant ears, Colocasia, are good for large ponds but too big for my little lily puddle. But not the smaller black versions like imperial taro and Black Magic. Once hard to find and very dear, they are now showing up on big box benches for five bucks. If you buy them as garden or container plants, that is. Triple that if you buy them as pond plants.

The quaintly named bloody dock - Rumex - also grows happily in water. And water celery, whose name should be a tip off.

The point is to get as many plants as cheaply as possible into that pond. Plastic water lilies don't count. And say good-bye to green water.

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