Cultivation is allowed in some areas under very controlled circumstances. In a couple of states, Florida and Texas, possession of it is illegal, with the fines in Texas of $2,000 per plant!

I'm looking into commercial possibilities so I'll be following the rules or else I may need to surrender my first-born son. (Wait, I already did that when he went in the Army ;>)).

I think I have read that the hollow-stemmed water cultured Kang Kong is preferred in terms of flavor?

I had a lot of luck rooting greens from the local Chinese market: I just put them outdoors in a bucket of water and practically forgot about them. Roots developed, I planted the offsets in a muddy part of the garden with no drainage, and voila.

It really seems like a good thing to grow if your yard is too wet for most normal vegetables. In zone 5, it's not going to be invasive for me, as it seems to be knocked back completely (read: dead and rotting) when the temperature drops into the forties.

Yes, they're very similar. One is soil grown and one is grown in water.

The seed I presently use was purchased in bulk from a Chinese store several years ago... fortunately, it has a very long storage life if kept in a sealed container. It is the "upland" type, which is more tolerant of cool weather & dry soil than the more tender lowland type. Not as tasty, though.

Local Asian stores may sell the seed in the Spring under one of its many names (look it up the species Ipomoea aquatica on Wiki), or they may sell the shoots in bunches as produce. The shoots root very easily in water, moist sand, or mud.

There is only one mail order source of seed that I know of, in Canada (see link). Don't know if they can ship the seed to the U.S., so you might want to contact them.

Ipomoea aquatica, like many semi-domesticated tropical vegetables, is daylength sensitive & and will only flower in short days. Unfortunately for most of us in the colder zones of the U.S., that is in late September... when cold weather puts an end to the growing season. When I grew it in San Diego, the plants flowered, and I was able to collect seed.

Unfortunately for those in the warmer zones, if your climate is mild enough for you to get seed, it is probably outlawed in your state. :-(

My method of rooting cuttings: Use the widest part of the stems (these should be rougher in appearance than the newer growth). Measuring from the base, cut them to 6-8" in length. Carefully cut or nip off all leaves, down to a bare stem... but avoid damaging the buds where the leaf joins the stem. Place the stems upright in a clear glass container (vase or drinking glass) with about 2" of water. Be sure all stems are immersed. Put the container in a sunny location; roots will form in a few weeks, and new leaves will emerge from the old leaf nodes.

A few shoots will usually rot; remove them promptly, and change the water. Avoid using treated (chlorinated) water, unless it has been allowed to "breathe" overnight.

For the past several years, the wife has been saving some shoots from the last cutting of the summer, and over-wintering them in a rectangular planter near a South window. Most of them survive. I still start most of my plants from seed, but these transplants are the first to bear, and it's nice to get a taste early.

I've had my seed so long, I can't remember what year it was given to me... it's been at least 8-10 years, and still has excellent germination. It has a very long life if stored properly. Use an air-tight container, preferably one just large enough to hold the seed. The more tightly packed it is in the container, the less air will be enclosed with the seed. Keep the container cool & dark, and only open it each year to remove that year's seed, re-closing it quickly.

I believe that excluding oxygen - and preventing the seed from drying - is the secret to the seeds' longevity. Seed packets that were sent to me in trade from the S.F. Bay area had significant germination loss after only 2-3 years. The seed I use now was originally a kilo from Known-You Seed, purchased through an Asian market.

Here in australia, you can get kangkong seed from asian grocery seed packet, not all asian grocery sell them tho. I happen to find mine at Boxhill, Melbourne at Yang Yang store near the fridge (just in case someone in melbourne want to buy some). A company called Minara Seed sell a lot of asian greens (based in QLD or sydney, it will come up on google).