Imagine pulling a sponge out of a bucket of water. The large pores drain water out and pull air into the sponge. The small pores hold the water. Roots on most plants need air in the soil as much as they need water.
There is a wide variety of soil types that hold different amounts of water and air. There is a wide variety of plants that are designed for all the soil types. Sandy soils hold less water and more air, and some plants prefer this type of soil. Soils high in organic matter have a lot of air but also hold a lot of water. Clay-based soils have few large pores, so they hold water and don’t have much air.
If you have properly matched your garden plants to your soil type, then your plants will be healthier than plants stressed by growing in the wrong kind of soil. The longer a plant has been growing in the proper soil, the larger the root system will be and the larger the sponge of soil that it can get water from.
Plants use a variety of techniques to cope with the lack of water. Wilting is of course one sign that we recognize for plants needing water. Some plants drop extra leaves or fruit that started growing in the spring when there was more rain. Some plants stop growing new flowers, leaves, and branches. Plants such as grasses in lawns stop growing and allow the leaves and many roots to die, but the plant keeps a crown of stem tissue alive that will start growing new leaves and roots when the water comes back. The dormant grass plant crown is still alive and still needs some water occasionally to keep the crown alive.
Many perennials also have crowns that will go dormant each summer during July and August when the normal dry season occurs. A dry summer starting two months early may be too long of a dormant season for these plants.
Rains from thunderstorms are not consistent. A hot, dry week or two is long enough for the soil to dry out so that rain is immediately soaked up into the dry soil and is not available for the plants. A large rainfall in a short time may mainly wash away and not sink into the soil very much. A large rain in a short time may make the rainfall totals look good but not actually help the plants. Dormant plants or plants that have reduced root systems will be slow to grow enough roots to make use of the rain.
So watch your plants to see which ones are showing signs of water stress, which ones are going dormant, and which ones don’t need much help. Water the plants that are showing stress, and water the plants that are dormant enough to keep the crown of the plant alive until better weather arrives.
You may have seen recommendations that plants need an inch of rain or irrigation every week to 10 days. This recommendation is based on many garden vegetables and perennials that are growing in good loamy garden soil. This type of soil will get wet six to eight inches deep with one inch of water. These plants will use the water in that size of soil sponge in a week or so before the soil dries out. New plants may not have a large enough root system to fill the whole soil sponge. Many landscapes have good topsoil only in the top four inches, so those soils don’t store enough water to last a week.
With good deep soil that holds a lot of water and some judicious watering, you can keep your landscape alive and healthy.
