By Seth Hawkins, GFC Urban Forest Specialist

Springtime is here and with longer days and warmer temperatures at hand, trees are waking up for the growing season. Trees’ water needs are also waking up, so it’s time to start a watering regime for trees that were recently planted or planted within the last two years.

So, how much supplemental water do those trees need? There’s a formula for that! A tree needs extra water for as many growing seasons as its caliper measurement at planting. (Reminder: caliper is the diameter of the stem, measured six inches above ground level at the time of planting.) For example, a two-inch caliper tree usually needs two growing seasons of supplemental watering and care to be considered established. An additional year of supplemental watering may be needed if that year has long periods of high temperatures and drought.

Another formula to remember is this: water five to seven gallons per caliper inch, once a week, from March through October-November, again depending on rainfall amounts. Example: a two-inch caliper tree requires 10-14 gallons per week in the growing season.

Tree roots do not like to stay wet all the time, so deep watering ONCE weekly is usually adequate. Higher temperatures and sandier soils may dictate a twice-weekly regime. If two or more inches of rain are received in a week, supplemental water is likely not needed. Check this fact sheet for more information: How to Water Your Trees. A GFC “Ask the Arborist” video about watering is also available here: Ask the Arborist Series: Best Watering Practices.

Spring can also be a good time to prune. By cutting out any dead branches or stems, better structure can be established and it helps the tree seal off the wound where the dead branch was. Learn more about the correct way to prune in this GFC video: Ask the Arborist Series: Best Pruning Tips & Techniques

This is an ideal time for an overall health check-up on your trees. If something doesn’t look right, GFC’s “Ask the Arborist” may be able to help. Find out why it’s important to hire a commercial International Society of Arboriculture Certified Arborist at: Ask the Arborist Series: Why Hire an Arborist and where to find one at

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