Soil Makes a Difference

by Andrea Laine, Extension Master Gardener Volunteer

I used to call myself a flower gardener, but nowadays I feel more like a soil gardener. I credit the master gardener training program for my transformation. I was blissfully ignorant before I learned how important soil is to gardening success. Well, perhaps not blissfully, but ignorant nonetheless. I am now convinced that if there is a silver bullet to successful gardening, creating great soil is a strong contender.

My transformation began with a soil test in fall 2014. A soil test chemically measures soil elements essential to plant nutrition, including phosphorus and potassium, and makes recommendations of lime and/or fertilizer. The test also measures the soil pH.

Soil Report

When you have your soil tested, you receive a report that details what amendments you need to make in order to satisfy the types of plants you intend to grow in the area from which you took the sample. I sampled an 800 square-foot area along the north border of my property that is already home to four mature trees, three rhododendron, two camellias and one Japanese holly. For several years, the area has been mulched annually with pine straw. I plan to add more rhododendron, camellia sasanqua and viburnum shrubs and perennials to this shady border. Thus, I had the soil tested for Crop 1 – Azalea/Camellia and Crop 2- Mountain Laurel/Rhododendron.

The landscape bed in early 2015.

The optimum pH range for azalea and rhododendron is 4.7 to 5.3. The soil report showed 5.7, which means my soil was not acidic enough for the garden I wanted to grow. Acid-loving plants may not grow or flower well in higher pH soils. And, indeed, the existing rhododendrons and camellias had hardly flowered at all. Not being in tune with my soil and its needs, I had guessed too much shade or too much heat was to blame, conditions that were largely beyond my control.

My soil was also deficient in phosphorus (P) and potassium (K). The agronomist’s report recommended 16 pounds of an acid-forming 5-10-10 fertilizer.

Amending Soil

The following spring I set out to make things right. First I picked up bushels of pinecones and raked away all the pine straw. I cultivated the soil by hand using a pitch fork to overturn it as deep as I was able, which was just two to four inches suggesting the soil had become compacted. (I was not surprised; it had not been turned over in at least 15 years.) Along the way I removed rocks of all sizes and encountered many roots. It was physically hard work. I consulted a few landscapers about doing the work for me, but none were interested. Then the hot summer months arrived and I lost interest in working outdoors.

Cultivating a mature landscape bed by hand was hard work. I struggled to penetrate compacted soil, made contact with many tree roots, and excavated these rocks

In October 2015 the camellias, which had a few blooms each in recent years, burst forth with a plethora of pale pink, fragrant blooms. Up to this point, the only change I had made was turning over the soil surrounding these shrubs. What a difference it made! (Sadly, I do not have a photo.)

Ideally, soil is composed of 50% solid materials (45% mineral particles and 5% organic matter, roots, humus, organisms), 25% water and 25% air. Roots grow best in soil with a balance of moisture, air and mineral particles. My camellias’ roots may have been starved of air or moisture.

I resumed my DIY project with renewed enthusiasm. I laid down a couple inches of composted wood chips in the area around the six existing shrubs and gently worked it into the soil. The chips were made from maple trees felled by an ice storm in winter 2013. (I did not put down pine straw in 2015 or 2016.) In March 2016, a three-inch commercial mulch of pine bark fines and compost in a 50/50 mix was applied to the area.


In April, the garden rewarded me with vibrantly beautiful spring blooms. I counted more than 30 flower clusters on just one rhododendron. New shoots are also growing from the base of the trunk.


rhodie bloom a









Absent a soil report, I doubt I would have gone to the trouble I did to improve my soil. And I am not finished yet. Organic matter is dynamic – bacteria and microorganisms break it down over time—so it must be replenished periodically. It’s been almost two years since I had the soil tested. Given the changes I have observed, I will have the soil tested this summer and again a few months after applying fertilizer. I will not add new shrubs to the area until I have successfully lowered the soil pH, something I cannot know without a soil test.   

Do as I Say, Not as I Do

In an ideal world, the best way to have renovated this particular landscape bed would have been to follow the steps below. I set out to do things this way, but limits on my time, strength/energy, and money caused me to follow a somewhat alternate route as I described above.  

The ideal process would have been completed in one season:

  1. Clear the debris – pinecones, twigs, leaves and old mulch.
  2. Cultivate deeply to loosen compacted soil. Compacted soil can prevent water from reaching a plant’s root system.
  3. Apply a three to six-inch layer of organic material (compost) and incorporate it.
  4. Apply the fertilizer recommended by the soil report and incorporate it.
  5. Another way to increase soil acidity is by applying elemental sulfur. I chose not to do this because the turnaround is slow and sulfur can harm existing plants as well as people.
  6. Wait a season or two and then retest the soil.

Although I had to cut some corners, I learned that a little TLC of garden soil pays big dividends. Now I know that being a soil gardener can lead to an outstanding flower garden.  

Additional Resources

Understanding the soil report:

Learn more about incorporating organic matter to amend soil:

Educational videos about soils:

Soil Test Peak Season

Are you planning to have soil testing done this fall? Well, the time is now. The NC Department of Agriculture charges a “peak season” testing fee of $4 per sample from November 25 through March 31, 2016. During the peak season, Master Gardeners will not be collecting samples in the Extension office or collecting payments; you will need to drop your samples and fees at the NCDA Soil Lab at 4300 Reedy Creek Road, Raleigh.

NCDA has provided some guidelines for peak season samples:

  • If soil samples are postmarked November 25th but arrive on November 26th, they will still be charged the $4 fee per sample.
  • Samples dropped off at the soil lab in Raleigh must take place during the business hours of 6am to 6pm, Monday through Friday.
  • Payments for soil samples submitted during the peak-season can be made via credit card or with an escrow account. Consult the NCDA Agronomic Division website for information on how to set up an account. Contact number for NCDA is 919-733-2655.

Soil tests will be conducted free of charge from April through November. During that time period, samples can again be dropped at the Extension office for delivery to the soil lab. If you plan to beat the fee this month, please call the Master Gardener office prior to dropping your samples off to make sure that the samples can be delivered to the lab in time.

Reasons to Soil Test this Spring

Are you planning to have your soil tested this spring? After March 30, the peak season fee for soil testing will not be applied. That’s right – you can have your soil tested for free!

Do you need more reasons to bring those samples in for testing? Here’s a list, courtesy of the NC Department of Agriculture and Consumer Services:


What is a Soil Test?
soil test is a process by which elements (phosphorus, potassium, calcium, magnesium, sodium, sulfur, manganese, copper and zinc) are chemically removed from the soil and measured for their “plant available” content within the sample. The quantity of available nutrients in the sample determines the amount of fertilizer that is recommended. A soil test also measures soil pH, humic matter and exchangeable acidity. These analyses indicate whether lime is needed and, if so, how much to apply.
Why Do You Need A Soil Test?
Encourages plant growth by providing the best lime and fertilizer recommendations.
When growers guess about the need for lime or fertilizers, too little or too much is likely to be applied. By using a soil test report, the grower does not need to guess.For Example: When applying too much lime, soil pH may rise above the needed level, which causes nutrients such as iron, manganese, boron, copper and zinc to become less available to plants.

It is also common to see homeowners purchase one bag of lime when they purchase one bag of fertilizer. Based on an average lawn size of 5000 square feet, one bag of fertilizer may be enough. Applying one bag of lime over 5000 square feet, however, will have little effect on soil pH.

Diagnoses whether there is too little or too much of a nutrient. 

Promotes environmental quality.
When gardeners apply only as much fertilizer as is necessary, nutrient runoff into surface or ground water is minimized and natural resources are conserved.

Saves money that might otherwise be spent on unneeded lime and fertilizer.
For example, growers of flue-cured tobacco often routinely apply phosphorus. In areas where soil levels are high in phosphorus, a soil test could save these farmers up to $60 per acre.

Soil test kits are available at the Durham County Cooperative Extension Office, 721 Foster Street. It’s easy, it’s free from April through November, it may save you money on fertilizer, it’s good for the environment AND your plants.

-Ann Barnes

Avoid the Peak Season Fee – Soil Test Now

This year, NC will be instituting a peak-season soil test fee of $4 from December through March. If you are planning to have your soil tested before spring, please submit your samples in November if you wish to avoid the fee.

Soil test kits are available at the Cooperative Extension office at 721 Foster Street. Collected samples can also be dropped off at the office.

Why do we recommend soil tests? Without the information a soil test provides, a homeowner has to guess how much fertilizer to apply to lawns, gardens, and landscape beds. If too little is applied, plants do not get all the nutrients they need to thrive. Too much fertilizer can burn plants, run off and pollute ground water and streams, and waste money.

NEW Peak Season Soil Test Fee

Peak-season soil-test fee coming this fall/winter

The 2013 Appropriations Act passed by the General Assembly approved a $4 fee for soil samples analyzed by the N.C. Department of Agriculture and Consumer Services for the period from December through March. The fee is an attempt to lessen the backlog associated with the busy season when the lab is routinely inundated with tens of thousands of samples. The rest of the year — April through November — NCDA&CS will continue to analyze soil samples without a fee.

In fiscal year 2013, the NCDA&CS Agronomic Division analyzed nearly 368,000 soil samples. About 60 percent of these arrived at the lab during the peak season of December through March, slowing processing turnaround time to nine weeks at one point. At other times of the year, processing can easily be completed in two to four weeks, depending on sample volume.

The new peak-season fee should accomplish two goals. First of all, it will encourage more growers to submit samples earlier, thereby fostering a more balanced sample load throughout the year. Secondly, the fee will enhance sustainability of the soil-testing program because receipts generated in fiscal years 2014 and 2015 are earmarked for improvements such as automated equipment, additional peak-season personnel and computer-programming enhancements.

The vast majority of soil samples analyzed during the winter months are from farms in preparation for spring planting. Most of these samples can be collected and submitted well before December 1st, thus avoiding the fee. Nearly all soil samples associated with home and garden and landscaping projects can be collected and submitted from April through November.

Soil samples received during the peak season will be processed in the order received without any guarantees regarding turnaround time. However, clients can purchase NCDA&CS expedited shippers to receive a guaranteed turnaround time of 10 business days. This year, 525 shippers will be sold. The anticipated 2013-14 price for a 36-sample shipper is $200.

During peak season, the sample receiving process will change. Sample drop-offs at the Eaddy Building in Raleigh must take place during business hours (6 a.m. to 6 p.m., Monday through Friday). A locked gate will prevent access afterhours and on weekends. This procedure will increase the security of samples and improve client access to Agronomic Division personnel.

By late fall 2013, clients will have the convenience of entering sample and payment (credit card) information online via the PALS website. Cash and checks will be accepted for peak-season samples only if deposited in advance in an escrow account. Payment should never be placed inside shippers.

This year, December 1st falls on a Sunday and is preceded by the Thanksgiving holidays. Wednesday, November 27th, will be the last business day of the month for the soil-testing lab. Any soil samples arriving after 6 p.m. on November 27th will be subject to the peak-season fee because they will not be logged in and processed until December 2nd.

Contact the NCDA&CS Agronomic Division office at 919-733-2655 if you have any questions regarding the new peak-season soil-testing fee or the purchase of expedited shippers.

(per NCDA&CS)