Thirsty Trees – How Much Water Does a Tree Need?
As with all living things, trees need a few things to survive. Sunlight allows for photosynthesis which creates nutrients for energy, soil for roots to grow and stabilize the tree, and water to help carry the nutrients throughout the tree and allow for transpiration. Even while some are more drought-tolerant trees than others, one of the most important factors in any tree’s survival is water. Especially in establishing or newly planted trees, the amount of water given to the tree can determine its ability to survive.
How Much Water Does a Tree Need?
Although our spring and early summer have been rather wet seasons this year, it’s inevitable that in Missouri, there will come a dry spell. As the summer heats up, the watering needs of our trees increase. Below is a chart of recommended water amounts for your trees if we don’t get a lot of rain:
Good slow soaking (10-15 gallons per every 5” diameter of tree trunk)
- 80+ degrees= every 3rd day
- 65-70 degrees= every 5th day
- 50-60 degrees= every 7th day
- 35-45 degrees= every 14-15 days
Note that watering is still pertinent in the colder months, just at a lower rate than the warmer months.
Best Way to Water Trees
Many people set their sprinkler systems and assume it will be sufficient for their trees’ watering needs. However, sprinkler systems are more suited for turf than trees. Trees prefer longer, slower soakings less frequently. Turf and trees will compete for water and when sprinkler systems are set, the amount of water given by these irrigation systems is taken up mostly by the turf with little left for the trees.
The best way to water your trees is with a hose set in the root zone and leave it running for several minutes. Be sure the water doesn’t spray the trunk of the tree which can eventually cause it to rot. It’s also not ideal to water the leaves, as water droplets in the sun can act as a magnifying glass and burn the leaves.
Watering is even more imperative for newly planted trees which are expending a lot of energy to root growth to become established. Also, some species of trees like Willows, Bald Cypress, and Birches prefer moist conditions while others can handle more dry conditions.
Drought Stress in Trees
Some indicators that your tree is experiencing drought stress from not getting enough water are:
- Wilting leaves
- Smaller leaves than normal
- Stunted growth
- Leaf drop
- Early fall color
- Dying or dropping limbs
- Leaf scorch
Adding a Mulch Ring
A great way to retain moisture and add organic matter for the tree’s root system is a mulch ring. Mulch mimics the forest setting which constantly has organic matter decomposing on the top surface of the soil. Adding a mulch ring around your tree eliminates competition with turf, is aesthetically pleasing to landscapes, adds nutrients, provides temperature control, and protects the tree trunk from mower damage.
The best thing you can do for your trees in the hot, summer months is provide adequate water. If you have any questions about the trees on your property and their needs, please give your local arborists a call.