Watering may seem a simple thing, but it is far from being that simple. There are many factors involved in watering, such as the needs of the plant at that time, its health, the weather, the season, the soil characteristics, and the mode of watering (sprinkling or soaking). Watering your garden should not be done according to a set schedule, but it should be done according to the present situation.
Plants develop their roots only where they can find what they need, like water, nutrients, and air. So if the water does not penetrate deeply into the soil, the roots will only stay near the surface. When there is no water supply, and the weather turns hot, the top part of the soil will dry out – killing the plant when it can get no more water as all its roots would just be concentrated there.
It’s important to understand how water moves in the soil. Water moves through soil by gradually wetting each soil particle as it moves along. A soil particle that is wet has a thin film of water around it which permits other passing molecules of water to move along and wet other dry soil particles below and around it.
When maximum soil percolation is reached, this is called the field capacity of the soil, when each soil particle hold the maximum water film around it without losing any water to outside forces. This is when air pockets are at their lowest incidence. But as the plant roots start absorbing water and evaporation continues, the spaces between the soil particles get opened up and the films of water diminish. This strengthens the pull of the soil particles against that of the plant roots and therefore the plant loses out and is unable to extract water. The time period in between field capacity and wilting point is when there is enough water for the plant to grow.
Healthy watering practice for your garden means to keep it from constant field capacity. External forces like temperature, humidity, and wind all affect the rate of water transpiration from the soil. Hot weather causes plants to absorb water so rapidly that they may wilt due to not being able to absorb water fast enough. Therefore, water more frequently when the weather is hot and less, when it is cool or humid.
A good rule of thumb is to test the soil before watering. If the top 4 inches of soil is dry, you may want to consider watering, but otherwise, you may want to hold off from watering. Plants use up much less water during cool weather and can go for a few weeks without much water, so you can definitely ease up on watering with the approach of winter.
Here’s more tips on watering the right way: