- Author: Janet Hartin
Most trees in California need supplemental irrigation above and beyond what Mother Nature supplies naturally. Even drought-resistant species need regular watering through their first growing season due to their shallow roots. Once trees become established, it's important to water less often but more deeply to encourage deep rooting and structural balance above and below ground. Both under and overwatering can lead to unhealthy trees and even death if the situation is not corrected. Trees receiving too little or too much water exhibit similar symptoms since, in both cases, water is not available to the plant. Trees initially wilt, grow slowly, and develop yellow leaves. Over time, growth stops and leaves become brown and drop. Overwatered trees often develop lower crown and root rot from one or more disease-forming pathogens.
Knowing what type of soil you have (soil texture) is as important as knowing the water needs of your trees. Use the ‘feel test' (pictured below) to find out how much water your soil holds and how often to water. Heavier clay-based soils hold water longer and drain more slowly than sandier soils that need to be watered more often for shorter periods of time.
Trees should not be watered on the same irrigation system used for lawns and groundcovers. Soaker hoses and drip systems allow trees to be watered less often but for longer periods of time than your lawn or groundcover. Avoid applying water too close to the trunk. Instead water half-way between the trunk and the dripline of the tree and outward. If you use a garden hose, apply the water on the lowest volume possible slowly, moving the hose every few hours to each of four quadrants around the tree.
Applying a 3-4 inch layer of mulch around the tree can reduce soil evaporation. Use only non-flammable mulches in fire-prone areas within five feet from the house and non-contiguous for the first 30' away from the house. In all cases keep mulch a few inches away from tree trunks to keep the trunks dry.
Tip: Before planting a tree, make sure there is adequate drainage. Dig a hole where you want to plant it (the same depth of the pot, which is about one foot) and fill the hole with water. Let it completely drain and refill it. Measure the time it takes to drain one inch using a ruler. If it does not drain more than one inch an hour it is not a good location for your tree. Avoid adding compost or soil amendments to try to correct the problem since tree roots will likely grow in circles, staying within the confines of the amended hole rather than growing outward the confines of the amended hole rather than growing outward.
- Author: Janet Hartin
Dear Community Members and UCCE Partners Throughout San Bernardino County,
I hope this finds all of you and your families well and staying healthy. Please note that, due to COVID-19 concerns, all UCCE San Bernardino County face-to-face program activities, classes, and other events scheduled through April 30, 2020 have been postponed, canceled, or converted to zoom meetings or other distance learning formats. However, our academics, program managers, and community educators remain on the job and available to assist you via phone and email. Volunteer Master Gardeners continue to address your home horticulture inquiries through their telephone (909)387-2182 and email helplines (mgsanbern@ucanr.edu).
Thank you for your understanding and your flexibility as we continue to provide research-based information in new and novel formats during this difficult time. Follow us on twitter (@MGPSanBern and @UCANRJHartin) and visit our website http://cesanbernardino.ucanr.edu/ for more updates including our Fiscal Year 2019/2020 Annual Report.
Have you ever thought about the parallel between preventive health care for people and integrated pest management (IPM) for plants? Both implement specific measures that reduce the risk of exposure to disease-causing organisms. According to experts, implementing preventive measures such as ‘physical distancing' (I prefer that term over ‘social distancing'), washing our hands thoroughly and regularly, covering our mouths when we cough, not touching our face, etc. greatly reduce our chance of contracting COVID-19.
In the plant world, IPM practices and principles that promote healthy plants greatly reduce the chance of damage from diseases and other pests. With a little extra time on your hands, implement these IPM practices for a healthier garden and landscape: match plants to their preferred climates and microclimates; select disease resistant plant varieties; provide well drained, healthy soil amended with compost and other organic products when appropriate; apply the right amount of water and nutrients at the right time, etc.
A ‘silver lining' of adopting these practices is that the need for pesticides is greatly reduced which keep our waterways clean, and preserves (and even enhances) populations of beneficial microbes, pollinators and wildlife.
Here are some other ‘silver linings' that I want to share with you in hopes they will provide some inspiration for you to ‘landscape greener' during what I hope is some extra downtime.
• Fewer vehicles on the roads has temporarily improved our air quality. With some extra time on our hands, we can all contribute to a more permanent solution by planting a tree or two! Trees store carbon dioxide that reduces pollution, cool urban heat islands, provide shade, reduce interior energy use and costs, provide habitat, connect us with nature, and beautify our neighborhoods.
• Improve the health of your landscape trees by loosening tight tree stakes and ties and adjusting sprinklers to keep tree trunks dry. Your trees depend on you!
• Stay in touch with family, friends, and even co-workers at a distance via 'walking chats' that improve our physical health and even reduce stress by increasing the “feel good” hormone serotonin. Keep it up and it just might earn you a place in the “100 mile a month walking club.”
• With more time to catch up on reading, consider downloading free UC ANR publications such as: ‘Sustainable Landscaping in California' anrcatalog.ucanr.edu/pdf/8504.pdf that provides tips on water savings, use of soil amendments and mulch, reducing pesticide use, and more.
• More time on our hands provides an opportunity to stock our ‘little free library' with vegetable and flower seeds for our neighbors. Don't have an official ‘library'? Build your own ‘seed sharing box!' Or, donate seeds and plants to a local food bank or other non-profit.
I hope that you and your loved ones stay well and healthy! We will get through this together.