Gardening With Clay Soil and Fallen Tree Leaves

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:

In regards to your question about whether to remove, or use, fallen leaves in the landscape there are a few things to consider. As a rule, it's is best to disturb your soil as little as possible, so the addition of non-diseased fallen leaves into your landscape can be beneficial, as they will act as an organic mulch conserving moisture, retaining even soil temperatures, adding nutrients, and improving soil tilth over time. To not impede air circulation and water flow in the landscape, it is recommend that you shred the leaves before using them, and as with any mulch, apply it 3-4 inches thick, leaving 2-3 inches from the trunks of trees and shrubs. This will also create a less friendly environment for plant diseases. As with any organic mulch, the leaves will break down over time and need to be replaced. If attractiveness is an issue, here is an article that discusses different types of mulch. http://ipm.ucanr.edu/PMG/GARDEN/ENVIRON/mulches.html

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)

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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  (//ucanr.edu/blogs/CCMGBlog/).