How Much Water Does Your Flower Garden Need?

By Steven A. Frowine and The National Gardening Association from Gardening Basics For Dummies

How do you make sure your flower garden has the right amount of moisture? Relying on natural rainfall would be nice, but natural rainfall is hard to count on. Gardeners always seem to have to supplement the moisture, a little or a lot. You just need to keep an eye on things and pay attention to your plants.

If you know what to look for, you can figure out your plants' watering needs. Plants actually prioritize when water-stressed, so look for the early warning signs:

If a plant isn't getting enough water, flower petals and buds are the first things to be jettisoned (or fruit if it has developed), because making and maintaining them takes so much energy and water.
Next to go are the leaves, which shrivel.
Then the stems flop.
Underground, the roots go limp.

Obviously, if your garden is in this condition, it needs more water.

Determining when a plant doesn't have enough water may seem to be a snap, but keep in mind that there's definitely such a thing as too much water. If puddles form in your garden or an area of it's quite soggy, all the pores in the soil fill. Roots need oxygen to survive, and waterlogged soil prevents it from reaching the roots.

Meanwhile, some plant diseases (like mildew and blight) travel via water and can develop and spread in soaked conditions. Sodden roots blacken and rot, and all the aboveground growth subsequently dies. Garden plants in these circumstances, of course, need less water.

Unfortunately, an overwatered plant looks the same as one that's underwatered! The reason is that an overwatered plant is actually suffering from dehydration because the roots have been damaged by too much water (actually, too little oxygen, because the water has displaced the oxygen); the roots can't absorb water, so the plant wilts. One difference is that overwatered plants don't recover from wilt when you apply additional water, but underwatered ones generally do.