Can u grow them in water or do they need a substrate of some type

Most herbs used in cooking originate from the Mediterranean area so they grow in a gritty soil sort of like a cactus mix so they can dry out between waterings. They need sun and warmth, and perfect drainage to make good tasting leaves. So, the answer is, they need well draining soil.

I'm in Florida and have trouble keeping some herbs alive through our hot, humid summers. It's not the heat, but they really don't like the humidity so I'm not sure how well you'll do growing them in a paludarium.

Hi. Welcome to NGA.

Short answer, yes. The plants will need to be weighted or in shallow containers covered by rock to keep them in place.
Basil, mints, pineapple sage, oregano, sage, stevia, thyme, lemon balm, and many other herb cuttings will thrive in a jar of water on your windowsill for months. The only herbs that don't grow well in water are annual herbs, such as dill and cilantro, which live just long enough to flower and then go to seed.

http://www.aquascapesunlimited...

http://www.gardeningknowhow.co...

http://www.motherearthliving.c...

http://www.tfhmagazine.com/det...