Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program Contra Costa County
Gardener's Request: I'm a new homeowner with a garden with clay soil apparently and trees that are now dropping leaves. How do I garden with clay soil and what should I do with the dropping tree leaves – use them in the gardening and how or disposing of them in my green bin?
MGCC's Help Desk Response: Thank you for contacting the UC Master Gardeners Program's Help Desk with your questions about gardening in clay soil, and whether to remove leaves from the landscape or incorporate them into the existing soil.
First, about gardening in your clay soil:
Your clay is made up of air, water, organic materials, and minerals. The balance of these ingredients determines your soil type. Clay soils are those that are often rich with nutrients, and renowned for their water retention capabilities, but can become compacted over time, creating a less hospitable environment for plants. This link provides information from UC Davis discussing how to work with your clay soil to get the best results. http://vric.ucdavis.edu/pdf/soil_managingclay.pdf
One of the most essential components to gardening in clay soil is creating good tilth (i.e., ability to grow plants, especially from seed). This is accomplished by carefully adding organic matter such as manure, compost, and/or planting cover crops to your existing soil. This article by a Marin County master gardener discusses the many ways that you can improve the tilth of a clay soil with organic matter. http://www.marinij.com/article/NO/20160304/FEATURES/160309921
Use of fallen tree leaves in the garden:
pix: UCANR
Thank you for submitting your questions, and I wish you luck in your gardening decisions.
Help Desk of the UC Master Gardeners Program of Contra Costa (JJM)
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: ccmg@ucanr.edu, 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/).
Help for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client Request: I have several eucalyptus trees on my property. They shed a lot of leaves. I'd like to use the leaves for mulch and possibly compost, but when I research these uses, I get confusing and/or contrary guidance. My request: Can I use eucalyptus leaves/cuttings as mulch and/or compost in the home garden?
Help Desk Response: We understand your frustration with the information you're finding on the use of eucalyptus leaves as mulch. In doing the research on your question, I too, found a lot of conflicting information. The Master Gardener Program is under the umbrella of the University of California so the information that follows is all based upon scientific research.
Eucalyptus Toxicity
While it is true that eucalyptus leaves do have some toxicity, the research shows that well composted eucalyptus leaves pose no problem when used as a mulch or when mixed at appropriate quantities into a growing medium. The research also concluded that fresh eucalyptus leaves were shown to be a good weed suppressant when applied to a depth of 4 inches (10cm).
Following are two articles by James Downer & Ben Faber on the subject of eucalyptus mulch and eucalyptus compost.
http://ceventura.ucanr.edu/newsletters/Volume_23_No129817.pdf
and
http://slosson.ucdavis.edu/newsletters/Downer_199429100.pdf
Composting
The University of California research concluded that, when handled properly, eucalyptus is safe for use in compost (i.e., incorporated into the growing medium). The toxicity of the eucalyptus are rendered harmless by the composting process, especially if you are working a hot compost pile. (See http://vric.ucdavis.edu/pdf/compost_rapidcompost.pdf)
When composting eucalyptus, the leaves are considered green plant material and will constitute the nitrogen part of the composting process. To effectively use eucalyptus clippings or leaves, you will want to mix them thoroughly with carbon-based materials such as newspaper, cardboard or other dry leaves or plant material.
The University researchers suggest, if you still have concerns, that you consider composting eucalyptus in a separate hot compost pile, keeping the pile well moistened and turning it often to keep the mix hot over a longer period of time.
Once the eucalyptus is well composted you can do a germination test to test for toxicity by using the compost as a medium to start 10-12 fast growing seeds such as radishes. If a majority of the seeds germinate, the eucalyptus toxicity can be considered neutralized by the composting process.
If you want to use fresh eucalyptus leaves in your landscape, the conclusion suggests to favor using them on the woody landscape plants in the home garden setting.
I hope this gives you the information you were looking for and sets your mind at ease.
Help Desk of the UC Master Gardener Program of Contra Costa County (BHD)
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: ccmg@ucanr.edu, 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/).
Advice from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Generally, used appropriately, coffee grounds can be beneficial to your garden. And if you search the internet you can find lots of information on their use. As in all things “internet”, the question is “what is appropriate”.
The Master Gardener program attempts to provide the gardener with scientifically based advice on gardening. The use of coffee grounds is no exception. Recently, Washington State University's Dr. Linda Chalker-Scott (Extension Urban Horticulturist and Associate Professor, Puyallup Research and Extension Center, Washington State University) updated her earlier 2009 review of gardening use of coffee grounds with the publishing of her latest review of the scientific literature: “Use Of Coffee Grounds In Gardens And Landscapes” (http://cru.cahe.wsu.edu/CEPublications/FS207E/FS207E.pdf). This latest review has been peer-reviewed.
While it is strongly recommended that you read for yourself the short 6-page paper, below are the edited excerpts from her findings:
Action list for using coffee grounds in compost
- Use no more than 20 percent by volume of coffee grounds in a compost pile. A diverse feedstock will ensure a healthy diversity of microorganisms.
- Don't assume coffee grounds will make an acidic compost; pH levels will change over time.
- Be sure to allow coffee grounds to cool before adding them to your compost; heat can kill your beneficial microbes.
- Avoid adding coffee grounds to vermicomposting bins; they can injure or kill earthworms in these confined areas.
- Understand that disease suppression from nonpathogenic organisms found in decomposing coffee grounds has only been demonstrated under controlled conditions on a handful of crops, including bean, melon, spinach, and tomato. Their efficacy in gardens and landscapes is unknown.
Action list for using coffee grounds directly as a mulch
- Apply a thin layer (no more than half an inch) of coffee grounds. Cover with a thicker layer (four inches) of coarse organic mulch like wood chips. This will protect the coffee grounds from compaction.
- Don't apply thick layers of coffee grounds as a standalone mulch. Because they are finely textured and easily compacted, coffee grounds can interfere with moisture and air movement in soils.
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BLOG editor's addendum: Most of the comments on Dr. Chalker-Scott's latest review center around “avoid adding coffee grounds to vermicomposting bins…” with more than a few anecdotal comments that it is common practice to use coffee grounds in compost bins. I think there is some clarification needed between compost bins and vermicompost bins… Her response so far is that she is reporting what is in the scientific literature. Vermicomposters should take special notice of this finding and manage their composting accordingly. You might search for further updates and discussion on Dr. Chalker-Scott's Facebook page “The Garden Professors”
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Help Desk of the UC Master Gardeners of Contra Costa County
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: ccmg@ucanr.edu, 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/).
all pix UC
1) rototill what's left of the current lawn and remove as many grass clods and rhizomes as I can gather up in this process
3) cover with newspaper
4) cover that with more soil (excavated from a large bed elsewhere in the yard; clean and much better structure) and compost
5) poke holes into the paper to plant some F. rubra plugs I bought (prematurely) and overseed with F. rubra seed.
6) cover with mulch.
Client's Reasoning
- the soil is so compacted that it NEEDS some cultivation, despite the risk of chopping up rhizomes (besides existing grass is not very healthy); I'm loathe to put off cultivation till spring because if we get El Nino type rain that could just exacerbate the clay soil structure (ie, further compaction)
- I can plant the grass plugs now through the newspaper
- F. rubra seed can take advantage of early rains now and newspaper will hopefully rot by spring so new grass seedlings can tap the underlying soil then when days lengthen, temps rise and growth rate increases
- If El Niño rains come, this approach will prevent excessive pooling and muddy bog conditions.
The other option is rototilling and sheet mulching now and composting and seeding in March or so.
I'd appreciate your thoughts and comments. Thanks very much for your time.
Help Desk Response: Thank you for contacting the Master Gardener Help Desk concerning your lawn conversion from Bermudagrass to red fescue.
Bermudagrass can be pretty tough to eliminate. The best methods include the following (summarized from very detailed University of California information located at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7453.html):
1. Herbicide such as Roundup™, during spring and summer. Herbicide will only be effective if applied when the Bermudagrass is growing vigorously, meaning it should be applied during spring and summer. Stolons may not be completely killed by herbicide, so cultivation may also be required, as further described below.
2. Withholding water during summer. This tactic is usually combined with cultivation, also further described below.
3. Shading. Sheet mulch with overlapping cardboard sheets, covering the cardboard with at least 3 inches of mulch. Mulch alone will not be effective. More information on sheet mulching, including a "how to" slide show, can be found here http://www.bayfriendlycoalition.org/LYL.shtml 
Based on the above, you can see that summer is the best time to effectively eradicate Bermudagrass by using a combination of methods. Herbicides will not be effective during late fall and winter because the Bermudagrass will not be growing vigorously. If you decide to cultivate and hand remove rhizomes and stolons, followed by sheet mulching, that is probably your best bet this time of year. However, we would recommend that you wait to plant the fescue plugs until you are confident the bermudagrass has been killed. If you do not, there is the potential that the bermudagrass will grow through the planting holes.
It is true that fall is the best time to seed Festuca rubra to take advantage of the rains. Festuca rubra is a low water use plant according to WUCOLS http://ucanr.edu/sites/WUCOLS/Plant_Search/. However, even plants that are classified as "low water use" require supplemental water for the first year or two to get their root systems established and are drought tolerant only thereafter. You may want to keep this in mind when deciding when, and how much, to plant, in case landscape watering restrictions continue next year.
General advice from the University of California about establishing and maintaining lawns can be found here, including information on pre-plant fertilizer http://www.ipm.ucdavis.edu/TOOLS/TURF/ We do also recommend that you have your soil tested to determine if certain nutrients are lacking so that you can fertilize and amend appropriately. A list of soil testing laboratories can be found at http://ccmg.ucanr.edu/files/51308.pdf. The soil testing labs' websites have instructions on how to collect samples and submit them for analysis, but you should contact the lab first to get their specific requirements for you situation. A basic soil test should include the major nutrients of nitrogen, phosphorus and potassium (N, P, K) as well as pH and organic matter. pH will tell you whether your soil is neutral, acidic or alkaline - this is important because pH can impact nutrient availability. Ideally you will want the soil pH to be between 5.5 to 7.5. 5% organic matter is considered ideal; our clay soils usually have much lower than ideal levels, but can usually be improved with the addition of compost.
Good luck with your ambitious project. I hope that this information is helpful. Please do not hesitate to contact us again if you have any further questions.
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Editor's Addendum: A relatively new development on the California turf scene is that at least one sod grower, and probably others as well, are now providing ready-to-install sod that consists primarily of native grasses and also touting significant reduction in water use. Your circumstances might warrant consideration of such sod. Details on feasibility and costs should be available at most retail nurseries or online.
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Help Desk of the UC Master Gardeners of Contra Costa County (JL)
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: ccmg@ucanr.edu, 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/blogcore/blogroll.cfm).
Help for the Gardener from the
Contra Costa Master Gardeners' Help Desk
Description of Client's Question:
A client wrote in saying that he had read some advice about using coffee grounds as a fertilizer. The advice apparently also noted that coffee grounds would be a deterrent to gophers and moles. About two years ago, the client applied about 500 pounds of coffee grounds in a small area, but stopped when his lawn and some native plants started to die. (But the client did note that the coffee grounds got rid of the gophers!).
The client said that even after he ceased using coffee grounds, the plants have not recovered and the lawn still looks dead. He thought that perhaps the soil had become too acidic and perhaps gypsum could be added to remedy the problem.
Here's the advice that Master Gardeners gave the client:
Soil acidity isn't the reason why nothing is able to grow in the areas where you applied coffee grounds, nitrogen depletion is. In fact, coffee grounds don't cause soils to become acidic. The acidity in coffee is water soluble and the acidity in the beans ends up in the coffee when the ground beans are brewed.
Oregon State University recently conducted a study on garden use of coffee grounds (http://extension.oregonstate.edu/lane/sites/default/files/documents/cffee07.pdf ). OSU found that large amounts of coffee grounds stimulate the development of soil microorganisms which in turn use the nitrogen in your soil to process the coffee grounds. The study also states that acidity of the resulting soil is not the major issue, but nitrogen depletion of the soil is a major concern.
I would try using a good organic nitrogen fertilizer and applying it to the area where growth has ceased. The organic fertilizers are slow release and will not burn your lawn or surrounding plants. It may take repeated applications over time to adjust the soil composition. If you have bare ground that is affected, you could also try covering the area with compost or leaves and let the natural composting process help to balance your soil.
Editor's Note: Each month the CCMG Help Desk's Quality Assurance Team selects responses to county residents' Help Desk questions that produced informative responses that are either unique or unusual, or provided updated information that would be informative to all gardeners, or are of general interest, especially of seasonal concerns. We are highlighting these responses in the HortCOCO blog so all interested Master Gardeners and the public may utilize the information.
The CCMG Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday 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: ccmg@ucanr.edu, and we are on the web at http://ccmg.ucanr.edu/
