How Much Should You Water Your Garden in Extreme Heat?

Extreme heat waves are stressful for almost every type of plant in your garden, from flowers and vegetables to shrubs and trees—but especially for container-grown plants.

During periods of high temperatures, you should monitor conditions, watering lawns and established plants deeply at least twice a week. Container-grown plants may require watering twice a day.

Learn how to water plants correctly during a heat wave and tips to protect your plant from heat-related drought damage.

How Much Water Does My Garden Need?

In general, for stretches of high temperatures and little rain, you will need to add about 1.5 inches of water per week or about one gallon of water for every square foot of garden.

The amount of water needed during a heat wave is highly dependent on soil type, daytime and nighttime temperatures, rainfall, and the type of vegetation.

The best way to determine if the garden needs water is to check the condition of the soil. If it is dry two inches below the surface, it’s time to water.

It is better to water deeply (soil is wet at least three inches deep) a couple of times per week than to water lightly every day. Light watering causes shallow roots that are not healthy.

Want more gardening tips? Sign up for our free gardening newsletter for our best-growing tips, troubleshooting hacks, and more!

8 Smart Watering Tips for Extreme Heat

Water Early in the Morning

Watering early in the morning helps ensure plants are fully hydrated for the hottest part of the day. It also allows wet foliage to dry quickly to help prevent disease.

Water Correctly

• Before watering, check the moisture of the soil. Apply water when the soil is dry to the touch two inches down. Overwatering can be just as harmful as underwatering.
• Use soaker hoses, drip irrigation, or spot watering instead of sprinklers. Water from sprinklers can evaporate in high heat before the water ever reaches the plant’s roots.
• High temperatures mean a high potential for water to evaporate before it ever reaches the roots. Avoid sprinklers and instead use spot watering at the base of the plant, soaker hoses, or drip irrigation systems to provide water efficiently.
• Set a timer on your phone or use a water timer on the irrigation system to avoid wasting water.

Mulch for Moisture Retention

Early in the growing season, add mulch around plants in the garden and containers to help conserve soil moisture and reduce watering frequency. 

Keep Up With Weeds

Weeds compete with plants for water so get rid of them in your flower beds and vegetable garden.

Practice Proper Pruning

Since many plants will stop blooming during extreme heat, deadhead spent flowers to keep the plants from spending energy on seed development. Deadheading helps prepare the plant to bloom again once the heat wave passes.

Check Pots Regularly

The soil in containers dries out much more quickly than ground soil, so check containers for moisture a couple of times daily. Set up a consistent schedule so they don’t dry out. Porous, unglazed terracotta or clay pots will dry out more quickly than plastic or glazed containers.

Pay Attention to Newly Planted Areas

Newly planted perennials, trees, and shrubs have not yet established deep roots. Check newly planted plants frequently and water deeply around the root ball and beyond to encourage root growth.

Planting, transplanting, and propagating are stressful on plants at any time of the year but more so during extreme heat. Wait until the heat wave subsides to plant or propagate.

Don’t Fertilize

Do not fertilize plants during periods of extreme heat because the stimulated growth adds more stress to the plant.