How Often Should I Water a Vegetable Garden in 100-Degree-Plus Weather?

Watering Schedule

• Without a strict watering schedule in 100-degree-plus weather, your vegetable garden will succumb to problems including drought and loss of water through transpiration. Plants expel water through their leaves in an effort to cool themselves during high temperatures, and if they do not have enough to drink to keep up with their rate of transpiration, they wilt and die. However, too much water also causes problems in the garden.

  A deep watering once a week is best to keep up with vegetables' need for water in hot climates. Established plants require the deepest watering to ensure that the moisture penetrates the soil and gets to the bottom of the plant’s root system. Plants with strong, deep root systems have a better chance of surviving heat and drought.

When to Water

• The time of day that you water plants in extreme heat plays a major role in your plants receiving proper hydration. During the heat of the day most of the water evaporates before it has a chance to reach the roots deep in the subsoil. The best time to water a vegetable garden is in the early morning, before 8 a.m., or in the early evening, after 6 p.m., so the plants have a chance to dry before the sun goes down. Wet leaves can lead to fungal problems.

  The morning is ideal, especially in 100-degree weather, as proper hydration during the hottest part of the day protects vegetable plants from wilting due to the heat. Seedlings are the most susceptible to burning and wilt on a hot day; therefore, cover tender plants with a cloth to prevent scorch or excessive water loss during the hottest part of the day.

Checking Plants

• While a weekly deep watering schedule is recommended for a vegetable garden in extreme heat, periodically check your plants to make sure they are properly hydrated. The top 3 inches of soil can be dry, but the soil at 4 inches needs to feel moist to the touch. Check the soil by hand throughout the week to determine if the plants need additional water to remain hydrated and protected from the heat.

Precautions

• Keep up with the weather forecast to determine if you need to provide supplemental water to your garden during a heat wave. In some instances high temperatures go hand in hand with drought, while other climates may experience frequent summer thunderstorms. Plants respond to drought and over-watering with the same symptoms, including browning leaves and wilting. If frequent rain provides a weekly deep watering for plants, supplemental watering might not be required.

  Soil should be moist, but not soggy. Standing water is never a good thing in the garden, as this makes crops more susceptible to pests and fungal pathogens. If the root system is exposed to too much water, the plant also loses oxygen and becomes incapable of taking in water.

Considerations

• Water is one element to protect garden plants from 100-degree heat and drought; however, mulch is absolutely necessary in such temperatures to prevent the hot weather from killing a plant’s root system. Roots begin to die when the soil temperatures reach 95 degrees Fahrenheit. Without mulch on a 100-degree day, the soil temperature easily reaches 110 degrees. A 3- to 4-inch layer of mulch around all garden plants protects and cools the soil.

  Mulch also helps garden plants retain moisture and adds organic matter to the soil as it decomposes. Increased organic matter in the soil improves drainage as well as the flow of water and oxygen to a plant’s root system.