What is Desert Horticulture?

Desert horticulture is a unique form of horticulture, very different from traditional horticulture in many ways. People who have gardened for many years in wet climates find themselves disoriented in desert climates. However, the laws of plant science have not changed, only how these laws are applied to the growing of plants.

Rainfall

Officially deserts should receive less than is of rainfall (4 cm) each year to be classified as a desert. However in a looser definition it has to do more with how much water plants could lose when irrigated. This involves both evaporation of water from nonliving surfaces combined with the transpiration of water lost from plants.

Irrigation is artificial rainfall. Desert plants respond to very quickly to rainfall and many times have evolved ways that keep them alive when rainfall is limited. When these rains come again, they spring to life. Drip irrigation is important in desert horticulture because it delivers this precious resource inexact amounts to plants and has the potential for conserving the most water of any form of irrigation.

When water is applied to native desert soils that have never been irrigated, rapid chemical and physical changes occur in many forms. Irrigated desert soils can damage plants, damage structures and cause many problems for the desert horticulturist.

Plants

Desert plants are uniquely tied to their climate. They respond to changes in their harsh climate that might threaten their lives.

Soils

Desert soils are unique because they develop under low rainfall conditions. There are oftentimes high in pH or alkaline in nature, salty, have very low organic content and contain a unique invertebrate and microbial community ready to flourish when water and organics are added.

Desert soils can be chemically and physically unstable when first irrigated because they have remained dry for so long. They are frequently rich in nutrients that have remained stable in this low rainfall environment for hundreds of years. Some of these high concentrations of minerals, like boron, sodium and chlorides can be toxic to plants. Others like sulfates can damage structures and other manmade contraptions in contact with this soil.

Sunlight

Sunlight intensity, the brightness of sunlight, in the desert can be quite strong. By some measurements, substantially stronger than sunlight in humid climates. Shade cloth that provides about 30% shade benefits many vegetables grown in direct sunlight.

Temperature

High temperatures are a hallmark of desert climates. It's one of the first things we think about when visiting the desert. The range in temperatures can be extreme in the desert, sometimes varying as much as nearly 75 ° F or more in a single day. Seasonally, temperatures might range as much as 100° F.

Shade is very important in desert climates. For humans and other animals, 100% shade can be extremely inviting on a hot summer day. But for plants, that rely on sunlight for a constant supply of energy, this is excessive. As an average, 30% shade is ideal for many flowering and fruiting plants. Plants that produce insignificant flowers and fruit may perform well under a higher percentage of shade.

Low Humidity

Low humidity does not sound like a big deal when growing plants. In fact, it is one of the reasons why plants grown in the desert have fewer disease problems than the same plants grown in a humid climate.

Salinity

Salts are common in desert soils and in some irrigation water.

Wind

Strong and erratic winds are a common feature of desert climates. Microbursts of winds approaching tornado speeds can be a common occurrence during cool spring weather hot summers.