September 11, 2023 /
Vincent Drader

Trees Need Water This September

For years now, Casey Trees has published our weekly watering alerts. Newly planted trees — those that have been in the ground less than three years — require 25 gallons of water, approximately 1.5 inches of rainfall, per week to survive. Our watering alerts let our community know if they need to water our young trees that week to ensure they grow strong and healthy.

These alerts used to run from late May to the end of August, but due to global warming and increased temperatures, we’ve expanded our watering alerts to begin at the start of May and extend into late September. With this year’s exceptionally dry spring and summer, and continued record high temperatures this month, it’s more important than ever to water young trees – even in September.

NOAA Drought MonitorThe extreme September heat will not continue this week, highs will be in the upper 70s, but less than half an inch of rain is expected in the next 10 days. The District is no longer in the drought condition it was in earlier this summer, but much of city (over 50%) and region remains abnormally dry, per the federal government’s National Integrated Drought Information System.

In fact, it’s been so abnormally dry that the Potomac River, which supplies much of the drinking water for DC, is running low. For the first time in a decade, the area’s water managers announced they may have to use water from backup reservoirs upstream. Although recent storms have filled the river and provided the area with much needed water, historically, late summer and fall are the most drought-prone times of year for our region.

The drought is affecting more than just river levels – it could affect the city’s trees this autumn. The DC region typically reaches peak fall color in late October to early November, but given this year’s dry conditions, some trees may lose their leaves earlier, before they are able to reach their most vibrant fall colors. We’ve already started to see several tree species lose their leaves- including london planes, black gums, dogwoods, and tulip poplars.

DC’s summer weather is fairly unpredictable every year, but rainfall this summer has been particularly unpredictable and localized, with some areas seeing scattered storms and flash flooding, while others experience only moderate rainfall. It is still important to water trees through the end of September. Continue to watch our watering alerts, and remember – anyone can help our urban forest by watering the trees on their street, and caring for the trees on and around their property.