Advice From the Help Desk of the
Master Gardener Program of Contra Costa County
Responding to Client's Phone Call Request: Thank you for calling the Master Gardener Help Desk with your question about replacements for your fallen oak tree. You were especially interested in our recommendations on small trees, possibly bigger “shrubs” vs. trees, planting them in a row (as many as 14), multi-trunk vs. single-trunk, overhead powerline friendly, and of course, drought-resistant. I think you are on the right track looking into multi-trunked plants such as upright manzanita, as 14 of those might make a more pleasing landscape than 14 standard trees. Since you have powerline considerations, you also need to be mindful of the eventual height of the plants.
You do have many choices, both evergreen and deciduous, for replacements for the old oak. The PG&E publication (Guide to Power-Wise Tree Planting... you can click the link at left for information on obtaining this free publication) that you have is an excellent resource for options. Some that would do well in central county as well as most of the county include western redbud, manzanita, strawberry tree (Arbutus unedo), California laurel, and crape myrtle. All of these have low or fairly low water needs, but the strawberry tree will also do well in a lawn. Another tree that isn't on the list, but would be appropriate, is Chilopsis linearis (desert willow). This tree has beautiful flowers that can range from white to rose to purple. It requires little water, so is a good choice for a drought-adapted landscape. All of the trees I mentioned can also be trained as single-trunk standard trees if you have a place in your landscape where that might be more appropriate. Toyon (Heteromeles arbutifolia) is another shrub that can grow to be a multi-trunked tree to 25' tall and wide. It takes pruning well, so can be shaped to fit the space.
We also strongly recommend that before you dig and plant the new trees that you call PG&E @ 811 to check the location of the gas lines on your property. The service is free.
Good luck on your tree replacements Please let us know if we can help you further.
Help Desk of the Master Gardener Program of Contra Costa County (SEH)
Note: The UC Master Gardeners Program of Contra Costa's Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523. We can also be reached via telephone: (925) 646-6586, email: firstname.lastname@example.org, or on the web at http://ccmg.ucanr.edu/Ask_Us/ MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (http://ucanr.edu/blogs/CCMGBlog/).
From the Help Desk of the
UC Master Gardener Program of Contra Costa County
UC MGCC's Help Desk Response: Thank you for contacting the UC Master Gardener Program of Contra Costa County regarding the remaining roots after removal of your large trees.
Based upon our research about invasive tree-root problems, there seems to be no real difference between ash or elm trees in the strength of their roots. Many other types of trees' roots are much more aggressive.
Regardless, these trees do have extensive roots that will try to live on reserve sugars for awhile. The roots will send up shoots as long as they are able, about a year or so, and if the leafy shoots find sun, they will try to grow. However, without sun, water and an unimpeded growing space, the weakened roots will eventually fail. To eliminate the trees from your garden, do not allow the shoots to succeed as that will create new sugars via photosynthesis from sunlight exposure.
You will have to be vigilant for a year or two, cutting back the shoots and sprouts as they pop up. Those severed roots under the foundation & walkways cannot live after their food reserve is gone.
Below is a a link to the University of California's Pest Note about woody weeds - which includes tree roots. It explains various methods to keep those tree shoots down and out.
Please do not hesitate to contact us again for garden assistance.
Help Desk of the UC Master Gardener Program of Contra Costa County (MKW)
Don't miss our 2016 Great Tomato Plant Sale:
Note: The UC Master Gardeners Program of Contra Costa's Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523. We can also be reached via telephone: (925) 646-6586, email: email@example.com, or on the web at http://ccmg.ucanr.edu/Ask_Us/ MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (http://ucanr.edu/blogs/CCMGBlog/)./span>/span>
From the Help Desk of the Master Gardeners of Contra Costa County
Client's Questions and Requests: (Originally from a phone call to the MGCC Help Desk...) I'm a new resident of central Contra Costa County having bought a house in Walnut Creek. The house and garden are probably 30-40 plus years old and mostly mature. There is a grove of 30-40 foot Redwood trees that look like they are doing o.k. and many other mature garden plants. We intend to do some remodeling on the house and garden which will include some new planting, but the redwood trees will remain in place for privacy and shade. In our replanting of parts of the garden we would like to utilize drought tolerant plants. We also have a creek adjacent to our property that we wish to protect with minimal disturbance. Do you have some guidance for us to consider as we rethink our garden.
As we discussed previously, We'd be reluctant to recommend planting redwood trees in central or east CCC (and with some reservations in west CCC). However, with your existing mature trees, the goal is to maintain their health and promote longevity. The links provided below provide information for redwood tree care and irrigation. You mentioned that the trees are very large and that they appear to be in good condition, so it is likely that after four years of drought they have been getting water from somewhere - maybe the nearby creek provides a high water table. However, even if we get rain this winter, drought conditions are likely to continue, and you may want to plan for future irrigation.
Although some mature trees can often survive one season with only one or two deep waterings during the spring and summer, several years without enough water can result in severe drought stress and even death. Drought-stressed trees can also be more prone to damage from diseases and insects as well as the effects of increased salts in the soil from lack of ample irrigation. Salts in the soil may also increase depending on the salinity of the irrigation water provided (such as may be the case with recycled water).
Here are some great articles about redwood cultivation in California that you may find helpful in deciding how to best approach improving and/or maintaining tree health:
The article in the link below addresses a new technique (TRIC) by UC horticulturists designed to water landscape trees by the home owner maximizing the use of water and insuring that water is reaching the drip line of the tree: http://ccuh.ucdavis.edu/public/drought/tree-ring-irrigation-contraption-tric-1/tree-ring-irrigation-contraption-tric. While TRIC system provides an effective optimal and automated solution, if the cost appears prohibitive, UC has now designed a simpler solution for less cost, but it requires more home owner attention and management (see RSIC).
You also asked about finding an arborist to inspect the health of your trees - the International Society of Arboriculture has a web tool to assist you in finding qualified members (i.e.,Certified Arborists) in your area: http://www.treesaregood.org/findanarborist/arboristsearch.aspx. You may want to consider a consulting arborist first as well as friends or neighbors for recommendations.
Finally, here is the link to the UC Davis Arboretum's list of good drought resistant plants for our area: http://arboretum.ucdavis.edu/arboretum_all_stars.aspx. We also have a lot more information on this subject should you need it.
Thank you for contacting Master Gardeners. I hope you will enjoy your new home, and if you have further questions please feel free to contact us again.
Help Desk of the Master Gardeners of Contra Costa County
Note: The UC Master Gardeners of Contra Costa's Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523. We can also be reached via telephone: (925) 646-6586, email: firstname.lastname@example.org, or on the web at http://ccmg.ucanr.edu/Ask_Us/ MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog./span>
- Author: MaryJo Smith
It's a cruel, cruel world out there – at least it is in your garden when water usage is restricted. All those beautiful trees, plants, vegetables and lawns need watering if they are to survive. But, what gets watered? Tough choices have to be made.
Your garden is like a medieval realm of yore, complete with a King, lesser nobility, merchant class, and serfs. We all know who gets the most (the King, of course) and who gets the shaft (the serfs, alas). So, lets break it down as it applies to our gardens.
The Tree is King. The Tree is so essential to our environment. It gives shade, helps cool the air, provides a habitat for numerous birds, animals, insects and fungi, it produces food, and it filters and cleans the air. Trees should be watered first, especially newly planted trees because it takes years for a tree to mature and it is less easily replaced than a bedding plant. You also want to give top priority to any newly planted shrubs. But remember, the Tree is King.
and there's the rest. . .
For more on how to care for your trees' watering needs, see UC/ANR California Garden Web - Keeping Trees Vigorous or Keeping Landscape Plantings Alive under Drought or Water Restrictions