Does rain count?

Soil moisture is a key component to happy, healthy, and productive landscapes. When adequate amounts of water are not available, roots dry out and die, and plants fail.

Over-watering prevents proper gas exchange, causing roots to suffocate from a lack of oxygen. Suffocation occurs because excess water displaces oxygen within soil pore spaces.

We commonly find many landscapes in mid-summer suffering from a lack of water. Homeowners are often perplexed: “But we had so much rain this spring”.

Sure, it seems logical that large quantities of water received earlier will remain available for plants later in the season, but this is not the case.

Think of a sponge. No matter how much water is poured on a sponge, it can only absorb so much. The excess flows away. Large storms delivering two or three inches of rain at one time provide only one inch of benefit to your plants.

Once soils in the root zone reach the water-holding capacity, any excess water drains away to the water table, and is unavailable to the plant roots.

Now, consider what happens when a brand new dry sponge is placed in water. It floats for a long time before absorbing water. Water does not enter a dry sponge easily. In fact, it is hydrophobic. Only after the surface tension is broken does the new sponge absorb water.

This is the reason water cannot easily enter dry, hardened soils. Light showers after prolonged dry periods are of little value to water-starved plants. Prolonged soaking is required to break the soil surface tension,

It is important to understand that plants need watering that penetrates soil 12-inches deep; this generally translates into one inch of water per week.

Because soils hold only a finite amount of water, landscape plants cannot sustain themselves for the entire growing season on spring rains alone. When soils dry out and become hard, they become impervious to water.

Accordingly, even more water is required to break the surface tension and allow water to penetrate the soil.

For plants to thrive, consistent seasonal moisture in the appropriate amount is required.