It's not quite as straightforward as some people think.
90% of health-related plant questions are due to watering, and of those, probably 90% are down to overwatering. So, if you want to learn a thing or two, read on...
1. ALWAYS water a plant in its existing pot BEFORE you plant it. The rootball needs to be full of water before you plant it - if it isn't, the rootball will stay dry despite watering afterwards, often leading to failure. And you must water it once you've planted it too, to add extra moisture to the surrounding soil and settle the soil around the rootball.
2. Roots are stimulated by DRY conditions, not wet ! Plant roots grow in order to seek out water. If they stay wet, there is no stimulus to grow, and more often than not, it will result in root rot and failure. The best way to water [most] plants is to soak them, and then allow the soil to dry out before you water them again. We generally advise against "a little bit every day" !
3. Garden soil stays damp longer than soil in pots, especially heavy soil - so you don't need to water your garden borders as frequently as your pots.
4. Young plants are far more at risk of overwatering than mature plants - the small root systems cannot cope with being constantly wet. As plants mature with bigger root systems, they become far more robust and able to cope with whatever Mother Nature throws at them !
5. You can't beat the "finger test" for checking the moisture levels in your soil. If your finger is damp when you've put it in the soil, rest assured the plant will go another day without water !
6. A plant suffering from overwatering will collapse and wilt, but so will a plant that is too dry. The way to tell the difference is the finger test - and a dry plant will spring back up within an hour or two after watering - a wet plant won't, and if it's collapsing due to overwatering, it may be too late to save it
7. Finally, a word about Bamboo - its about the only plant where you can ignore points 1 to 6 ! Bamboos love water, and its almost impossible to overwater them. When you water them, give them at least a whole watering can.
And if you have to grow bamboos in pots, give them as big a pot as you can and be prepared to water them daily once they are established. Bamboos, especially the bigger species, will be much much happier when planted in the ground. Whereas most plant related issues that we discuss come down to overwatering, with bamboos its always - ALWAYS !! - down to underwatering.
The good new is that, once bamboos are established, they generally look after themselves (apart from when they're in pots !)
Hope that helps some of you who are learning about gardening ?