Keeping a garden and outdoor potted plants thriving during extreme hot days and heatwaves is often a challenge for gardeners. The temptation for many gardeners is to water their plants several times a day, which will work, but uses more water than is necessary. Fortunately there are several measures that can be taken in order to keep plants healthy while using a minimal amount of water.
Amend your soil so that it drains water well. The better your soil can absorb water, the less that will be lost through evaporation. For outdoor potted plants with hard clumpy soil, you can simply dump out the old soil and add new potting soil (all purpose is usually okay). In your garden, many plants, such as marigolds and hostas, can be dug up so you can till your soil about 18 inches deep and mix in about six inches of organic matter. Then the plants can be replanted in the new soil.
Mulch around the base of all your plants. Use about three inches of mulch, such as bark or pine needles, and cover the entire root area. This will help prevent water from drying up so quickly after you water your plants.
Water near the base of your plants during the coolest part of the day, which is around 6:00 a.m. in most areas. Also, water your plants slowly rather than quickly, as this helps the soil absorb more water.
Alternatively, water your plants with a drip irrigation system. Drip irrigation kits are available at most local nurseries or home improvement stores. They use a special hose that is attached to your outside spigot. The hose is placed throughout your garden either on the ground to water directly into the soil or on stakes to water from above. You can even use a timer to set it to water your plants only in the morning or to slowly drip throughout the day, which is also a very efficient way to water plants during extreme heat.