It is not a method of propagation mentioned with favour (if at all!) in most worthwhile textbooks on horticulture. Many plants will grow roots in water, but they'll be the water-collecting roots. So when you transplant it, you'll usually end up with a weak plant which has to work doubly hard to stay alive while it tries to produce its anchor roots and its eating roots etc.

Also think how many nutrients there are in water, compared with soil.

Stands to reason, doesn't it? I mean, water is NOT the natural growing medium for most plants. Not the popular culinary herbs, anyway.

You run great risk when striking plants in water that the stems will rot, and bacteria in the water will be absorbed and will spread throughout the plant, giving it a very poor start in life. The plant will not be able to cope with large amounts of these bacteria, as it would in the soil where it has its own defensive mechanisms. You'll need to change the water every day - very unsettling for a plant have a new transplant operation on a daily basis!

It's easy and kinder on the plants to strike cuttings directly into soil. If you're particular, you can buy special cuttings mixtures which are finer than the usual potting mixes. Strike cuttings in a deep pot to give the roots are fair chance to grow downwards.

Don't bother with hormone rooting powders or gel. I have always found that if you dip the cut ends into pure honey, I've had better strike rates. It's antibacterial, and helps encourage root formation. You can't use it in water.

I'm sure there are plenty of people who will disagree with me, but I never recommend striking cuttings in water.

We're not talking hydroponics here, where the water is very carefully dosed with precise amounts of nutrients and other chemicals at certain intervals of time - and where the end-product is usually a short-lived plant anyway.

I am not sure about the water roots, but to be careful, you can put them in water in something clear, and when little nubbins of roots show you can put them in pottingsoil. I do this when I don't know if things will root. I root plumeria cuttings in water, because I've broken so many roots in perlite, and I am afraid to do soil. :o) But a lot of culinary herbs root very easily in soil, you can put a baggie over them to raise the humidity.

I have had great luck with Thai Basil cuttings in water. I put them in a plastic cup with a baggie over the top and have roots in a week. The plants adapt well to soil when I put them outside. I've had no problem planting basil cuttings that have been in water for as long as a month.

I attempted to root some mint cuttings in perlite with a plastic bag over the top, but they went moldy! And this was even though I took the bag off every day for a few minutes to air them out. One day they were fine, the next day they had black mold all over them. Only one of six survived that.

Would cutting holes in the bag reduce the chances of mold? Can I do without the bag altogether? It's fairly humid where I live anyway.

Try it. Try some covered, some not covered, some covered loosely/bags with holes. See what works best in your conditions. If you have a warm, humid place already, I wouldn't think much covering if any is needed.

I read an article one time about killing plants. Wait it's not what you think! It's about trying different locations, methods, and so on in your gardening practices. The author was of the opinion that you have to be willing to kill a few plants in order to find just the right methods, placement, plants, etc. for your gardens. And to some extent, I have to agree. It's all about learning through trial and error. Some gardeners like to keep journals which helps them keep track of their learnings.

I never heard the honey bit that Daisy mentioned. It makes sense - simple sugars for the plant to feed on along with some antimicrobial action. If you're going to try the honey thing, I would make sure to get raw honey. A lot of the honey sold in supermarkets (at least in the US) is pasteurized and filtered to death. The raw honey is where you will find the enzymes and antimicrobial stuff that the heat in the pasteurizing process destroys. Raw honey is generally marked as such. Check out your local farmer's markets and orchards for raw honey.

FataMorgana

I have a few flower pots on the front deck. Early morning sun dappled till noon then shade. I just stick cuttings in with the flowers. Then transplant after a few weeks.

If the cuttings are woody then I will put a soda bottle with the bottom cut out over the top of them. Some times with the lid on some times without. I have good luck with about everything.

For roses I use gallon jars and more shade. Start them right in the ground.

I have rooted Chinese basil easily in a jar of water. It takes 2 or 3 weeks for the roots to get long enough, and hardly any of the leaves turned yellow. Since I intended to grow them in a passive hydroculture system, water roots are what I wanted. It took them another week or so to get used to being outdoors, but they're doing fairly well now. I've even had to nip off some flower buds.

I put some pineapple sage cuttigs in a jar of water ten days ago and they have already developed roots. Figured I'd move them to individual jars and start adding soil. In a couple of weeks they should have a fairly good root system and be ready to pot up.