What are the best watering practices for peak summer heat?
The only way to ensure moist soil in DC’s August heat is to maintain consistently thorough watering. First are watering fundamentals—the when, where and how to water. Second, there are few tips and tricks that can elevate your watering practices.
The Fundamentals
Plants need water when their soil is sufficiently dry. Test by sticking one finger into the soil two inches deep for in-ground plants and one inch deep for potted plants. If your finger is wet with moist soil, it’s not yet time to water. If dry, slowly water the soil around the base of the plant. On days without rain, new plants always need daily watering until established.
Perennials, annuals, vegetables and herbs, shrubs, and container plants all require different watering frequencies. Water perennials deeply once or twice per week, and once or twice per day for annuals. Water vegetables deeply about two to three times per week and, similar to perennials, more often if conditions are dry. Container plants require more frequent watering, about once per day or every other day. Water shrubs such as hydrangeas about two to three times per week.
The when: Morning is the best time of day to water plants, before temperatures are too high. This allows plants to absorb water throughout the day. In contrast, nighttime watering can aid fungal diseases and root rot when unabsorbed water persists.
Don’t water plants during the midday period —11:00 a.m. to 2:00 p.m.—due to water waste from evaporation. Many plants are susceptible to sunburn when wet leaves are roasted under peak UV index.
The where & how: Watering technique is critical to soil moisture and plant health. Water around the base of the plant to target root systems and avoid splattering soil onto leaves. In contrast, overhead watering is a significant waste of water and can enable fungal growth.
Elevated Watering Practices
Mulching garden beds with a few inches of organic material such as pine bark retains moisture, suppresses the growth of weeds, and adds nutrients to the soil. Moreover, mulch maintains a cooler soil temperature thus reducing watering.
Other soil amendments can also help maintain consistent moisture levels, such as vermiculite, coconut coir and Soil Moist Water Aide. Vermiculite and coconut coir retain nutrients and water in the soil and, although they are mostly utilized in raised beds and pots, can also go in the garden. Soil Moist Water Aide is best used for just container gardening.
The best practice anyone can do to ensure their garden survives the summer heat is to landscape with drought-tolerant plants native the D.C. region. With native varieties, watering requirements are often minimal—even in August.
Tools such as soil moisture meters are valuable. They can measure pH, moisture and light levels. Taking these measurements in the garden throughout spring through fall provides useful information about the seasonal needs unique to a given space.
Drip irrigation systems guarantee consistent, deep watering. However, conserving water usage is critical, which is why irrigation systems are most efficient and environmentally friendly only when connected to a rain barrel.
For more affordable or immediate watering solutions, ollas can help. These in-ground, water-filled terracotta seep moisture into the soil. Similarly, terracotta spikes can be placed in garden beds and planters with water-filled wine bottles, for a cheaper and space-efficient alternative. Self-watering planters provide similar benefits. Finally, there are many popular plant apps that provide notifications to ensure even the busiest of gardeners won’t miss a watering day.
Gardening advice, information and commentary from the Capitol Hill Garden Club. Send your questions to [email protected]
Want to learn more about gardening or spend time with people who like plants? the Capitol Hill Garden Club, more information on the club website at capitolhillgardenclub.org.
