How To Submit A Soil Sample

Where to Send Your Soil for Testing

We now use two test labs – A and L Western Agricultural Lab in Modesto CA – and Midwest Laboratories in Omaha NE – When using our services all tests can be ordered without recommendations, as they will be provided by Timberleaf. A and L Western should be used for soils originating from the following California Counties –

Alameda, Contra Costa, Humboldt, Lake, Marin, Mendocino, Monterey, Napa, Santa Clara, Santa Cruz, San Francisco, San Mateo, Solano, Sonoma, and Curry county in Oregon. Soils from the above counties cannot leave California due to the prevalence of the Sudden Oak Death fungus in those areas. Order the S3CA soil test package.

Midwest Lab can be used for all soils originating in the remaining Counties of California and all other US states. Order the S3C soil test package.

Soil texture (% sand, silt, and clay) is recommended if it is within your budget. Or you can easily figure it out with the instructional clip at –

Soil sampling instructions for all samples can be viewed here –

Send your soil sample and payment to the appropriate lab. Once you receive your sample data results from the lab, email them to us along with a completed copy of the Soil Sample Information Form and payment. Payment can be made by check or Paypal.

Contact us if you have any questions at or (951) 677-7510.

What You Need To Get Started

Sample Soil Information Form (Click Here)   |   Quart Size Zip-lock freezer bags   |   Collection tools (See Soil Sample Collection Process Below)

Soil Sampling

The most important step in testing soil is making sure that the sample you submit is representative of the area tested.  The results you obtain are only as accurate as the sample you submit.  Following the steps listed below should help ensure the accuracy of your test results.

Soil samples can be taken any time of the year.  However, soil sampling is typically done prior to cultivation in the spring, and in early fall after the summer harvest is completed.

It is important to avoid areas or conditions that are different, e.g., spots where fertilizer or lime have been spilled or recently applied, fertilizer band areas of last year’s crops, compost piles, field borders, and poorly drained areas.

Step-by-Step Collection Process

Sketch Testing Area

Draw a sketch/map of the garden or mini farm field(s) you would like tested.  Be sure to show the major points of all adjacent areas, such as roads, other fields, buildings, shade trees, creeks or rivers, ponds, etc. surrounding the area you are testing.  Mini farmers should draw a sketch of their entire farm.

On the map/sketch, assign a name, number, or letter for each separate soil sample submitted for testing.  Write these numbers and/or letters on your sketch/map.

Examples – Field or Garden Name, Sample 1, 2, 3 or A, B, C

Sample Sketch/Map of a Garden*

* Reprinted with permission from A&L Eastern Agricultural Laboratories, Inc., Richmond, Virginia

Sample Sketch/Map of a Mini Farm Field*

* Reprinted with permission from A&L Eastern Agricultural Laboratories, Inc., Richmond, Virginia

Sample Different Soils Separately

Soils that differ in soil type, appearance, or past treatment should be sampled separately.  If one area of your garden or mini farm appears healthy while another portion is growing poorly, sample each area separately.

Avoid taking samples when the soil is too wet to till.

Soil Sample Collection Process

A soil-sampling probe, an auger, or a spade may be used to take soil samples (cores). The most accurate core samples are obtained with a soil-sampling probe. Gardeners do not need to go to the extra expense of purchasing one.

Sample Collection Tools *

* Reprinted with permission from A&L Eastern Agricultural Laboratories, Inc., Richmond, Virginia

Do not touch the soil with your hands or use galvanized, soft steel, or brass tools when taking core samples. The best equipment to use for sampling is a stainless steel or chrome-plated soil probe or spade.

Carefully follow the next steps as you take core samples.



Prepare Soil Surface & Bore or Dig Subsamples

Scrape away any surface litter, weeds, or mulch. If a soil-sampling probe is used, obtain a small portion of soil by making a boring 8 inches deep for cultivated ground, gardens, pasture, and hay land and 6 inches deep for sod and lawns. If a spade is used, dig a V-shaped hole to the sampling depth of 6 to 8 inches – then cut a thin slice of soil from one side of the hole.  If possible, break up any soil clods, remove stones, and roots from core samples collected.

Each composite (final) sample you submit should consist of approximately 7-10 core samples taken from gardens, raised beds, or small areas, or 15-20 core samples for larger areas and farms.  Walk a random pattern over the sampling area when taking the subsamples. (See sketch map above)

Bag Composite Samples

After obtaining the required number of core samples of soil, mix them together very thoroughly in a clean plastic bucket with a stainless steel spoon or tool for your composite sample. Do not dry the samples. Place enough soil from the plastic bucket into a zip-lock quart-size freezer bag to fill the bag – approximately 1 1/2 pound of soil per sample. Seal the bags tightly. This is your final sample.

Label Bags

Clearly label each bag with your name and address, and the corresponding sample and field numbers you entered on the Soil Sample Information Form. Keep a record for yourself of the area represented by each sample.

Fill Out Soil Sample Information Form(s)

Fill out a separate Soil Sample Information Form for each sample you submit. Be sure to complete this form in as much detail as possible. The more information you provide, the more accurate our recommendations to you will be.  Be sure the sample number on this form corresponds with the number on the plastic zip-lock bag.

Note Regarding Follow-up Soil Samples

When you are submitting follow-up soil samples previously tested by us, use the original sample number and note the original soil sample report number on the bottom of the Soil Sample Information Form.


Pack Soil Samples for Shipping

Place all soil samples in a sturdy container and pack them tightly to prevent spillage during shipping.


Seal Shipping Box 

Before sealing the container, enclose one completed Soil Sample Information Form for each sample submitted and a check payable to Timberleaf Soil Testing for the number of samples enclosed.

We recommend mailing by priority mail flat rate packaging, or any shipping service that easiest for you.