Let it float in your tank. Don't try planting it in the substrate it'll just die and you'll have little needle like leaves all over your tank. When you let it float, it'll grow like a weed. This plant is mainly used for new tanks to suck up extra nutrients to supposedly help the tank cycle faster. After that, most people just get rid of it but i've found out it's a good plant for guppy fry to hide out in at the top of the tank.
Concur with letting it float, generally I also take a few sprigs and encircle the heater cord and the bubbler tube. I run a dual light setup with a 6700 k plant flourescent and a standard 8000 k over my molly tank. About every other two weeks I will reorganize the hornwoot basically just rotating the bottom to the top, middle to bottom, top to middle.
Growth is good, especially if you add liquid nutrients like Flourish brand products. Molly fry (not so much swordtail for some reason) love to hide out in the hornwoot and as this is my 3rd generation of fry since I started this tank that has come to maturity my LFS is most appreciative with store credit.
One bit of caution is the the substrate plants beneath the hornwoot are limited to low light such as Cryptocorne Lutea for example. All in all a fine addition to a tank thats definitely got a corner of my 37 all to itself.
thanks for the input everyone , i just added the plant 3 days ago to this tank, and it started to lose needles after a day in the tank . i did not put it in the gravel as i know this is a rootless plant i did attach it to a rock , with adding the plant in 3 days i dont think its a issue of rotting due to being attached to a rock . it seems way to soon for it to under go a strong healtly bushy look to a thin leggy eye sore any ideas what could cause it , this is a low light tank 1 wpg around there and water is all good i just can understand how in the span of three days it would sheed so fast and so much. the needles arnt any odd colors so it looks like green healthy parts are shedding.
i will definetly try that thanks, i took it out of the tank cleaned up the mess as best i could and put it back , i have a high flow in the tank so its just turning over and over, thats why i tied it down, i figured if anything the constant movement ould have been worse for it since hornwort usuall likes slower water so i figured in the corner tied down it would limit the movement, iam just blown away at how fast the leaves fell out, but i;ll try the floating method anyone know how long this plant takes to settle in to a tank i realize each tank is different but anyone had a time frame approx ?