Helpful documents:

• Caring for Trees (PDF) 
• Managing Trees During Drought and Water Restrictions - The Britton Fund (PDF)
• Maximizing Benefits of Trees in Hot Climates - The Britton Fund (PDF)
• Improving Soil Conditions Around Existing Trees - The Britton Fund (PDF)

Jump to sections below:  Watering, Mulching, Pruning, Wildlife-Friendly Tree Maintenance

Watering

Trees of all ages require watering to remain healthy. Proper and sufficient watering of trees is vital to the health of our tree canopy. Drip or flood irrigation over the critical root zone (under the tree canopy) is usually the best way to water trees. A good system is calibrated to adapt to the soil, weather conditions, and tree type prior to installing and irrigating. If you don’t have a drip irrigation system, you can make your own tree watering bucket by drilling one ¼” hole in the bottom of a 5-gallon bucket. Fill the bucket with water and place it at the base of a tree to provide a slow trickle of water that can sink into the soil. Avoid spray irrigation if possible. If this is the only option, make sure the sprinklers to not spray the truck of the tree.

A tree’s watering needs depends on the age of the tree. See below for details on watering trees at different stages of growth:

Freshly planted trees require regular watering to become established. At the time of planting, a basin can be constructed around the tree, slightly larger than the root ball to help direct water to the tree's roots. Fill the basin two or three times a week, as needed, to keep the root ball moist. 

Newly planted trees need 5 – 10 gallons per watering, 2 – 3 times per week (or 15 – 25 gallons per week). More frequent watering may be required during periods of hot weather. Be sure to water the entire root area and slightly beyond. Since soils and environmental conditions vary, periodically check the soil to see that it is not too wet or too dry and that you are watering deeply enough.

Young, established trees that no longer have support stakes require infrequent deep watering for root development and good tree growth. A system that allows approximately 40 gallons of water to infiltrate per watering is a good starting point to keep the tree's roots moist. 

Mature trees may only require watering in the hotter summer months. Water should be applied under the drip line when possible. Trees should be watered so the soil is at field capacity (the water remaining in soil after it has been thoroughly saturated and allowed to drain freely). Watering needs many vary by species.

During extended dry periods, it is important to keep trees properly irrigated to preserve the City’s urban forest. You can conserve water while irrigating your trees by watering at night or early in the morning and ensuring that your trees have a thick layer of mulch under their canopy. 

Video: Watering Young Trees (Tree Davis)
Video: Watering Mature Trees (US Forest Service)

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Mulching

To conserve water, cool the soil, improve soil health and control weeds, apply a 4 to 6–inch deep organic mulch around the tree. Leaves, wood chips and other organic mulches are best as they break down over time and contribute organic matter to the soil. Avoid rock mulch, plastic sheeting and weed cloth as that can heat up the soil and roots of the tree and inhibit oxygen in the soil. Plastic will also hold too much moisture in the soil and inhibits oxygen exchange, leading to root and trunk rot. 

An initial barrier of newspaper or a single layer of cardboard can be used to help reduce weed growth for new mulching under trees. To avoid crown rot, keep the mulch off the tree trunk. Trees will often make their own mulch as they drop leaves, so go ahead and “leaf” them where they land for a natural mulch around your tree. If leaves fall on your lawn you can mulch mow them into the grass—no raking required!

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Pruning

During their lifetime, trees will require pruning. Pruning is an important part of an overall tree care program. Pruning should be performed for the following reasons:

• Remove dead, damaged, and diseased branches
• Correct or remove structural defects
• Restore the canopy after a catastrophic limb failure
• Reduce branch weight

Proper pruning builds structural stability in the tree and promotes tree health. Tree pruning should be performed by a qualified tree service that is licensed and insured for the protection of the tree owner. A Certified Arborist, Tree Worker or Board Certified Arborist should be on site to supervise the work and follow the written job specifications See our quick documents section for proper structural pruning details or see our Urban Forestry Other Resources page for places to learn about proper tree pruning.

Please note that certain trees, even trees on private property, cannot be pruned or modified without a permit. For more information, check out What is a City Tree?

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Wildlife-Friendly Tree Maintenance

The City's urban forest provides significant benefits to the residents of Davis, but did you know the urban forest also provides habitat for the wide variety of wildlife that call Davis home? While maintenance of these trees is necessary to support tree health and vigor, as well as to protect near-by structures and ensure public safety, tree maintenance activity can harm nesting wildlife if not done thoughtfully.

Birds and their nests are protected by state and federal laws. The breeding season for most species is from March to August. Tree pruning or removal during this time presents a risk of killing or injuring birds, their nestlings or eggs. Nesting adult birds may even abandon their eggs or offspring if there is elevated disturbance in or nearby the nest tree.

Please see the tips below on maintaining trees without harming wildlife: 

1. Any time you need to undertake tree maintenance or removal, ensure that it is absolutely necessary.
2. Consult an arborist to advise on tree health or public safety concerns.
3. Contact the City's Urban Forestry program to make sure the tree is not a City tree, Landmark tree, or has other restrictions on the maintenance of the tree.
4. When possible, tree maintenance or removal should only occur between September and February.
5. If you must conduct tree maintenance during the spring and summer months, please have a qualified wildlife biologist, or someone familiar with bird breeding behavior, survey the tree for nests. Contact the City of Davis Ecological Resources Manager at 530-757-5686 if you need help finding someone to survey for nests. Do not disturb the tree if nests are present. Nests are protected by state and federal law and destroying them is a misdemeanor.
6. Hawks and owls often reuse old stick nests. Avoid removing them if possible.
7. Contact the Davis Ecological Resources Program Manager if you find injured, displaced or dead wildlife. Please call 530-757-5686.

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