Learn With Us, week of September 8

Compost and Soil
Saturday, September 14⋅10:00 – 11:00am
Durham Garden Center, 4536 Hillsborough Rd, Durham, NC 27705
COMPOST & SOIL: The science, the mystery, the magic.
This talk will address local soil issues and how such challenges can be overcome with information gleaned from soil testing as well as proper and timely amendments. The basics of successful composting and vermicomposting will offer tips on how to transform food scraps, leaves, clippings and other organic materials into a nutrient-rich soil conditioner that will benefit your lawn and gardens. Simple composting practices and procedures available to all will also be covered.

Free/Registration required

Contact: 919-384-7526 or http://www.durhamgardencenternc.com

Sign up at the store, online or by phone
Include the seminar title and full name(s) of persons attending

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: http://content.ces.ncsu.edu/extension-gardener-handbook/1-soils-and-plant-nutrients#section_heading_7239

Educational videos about soils:  http://forces.si.edu/soils/

Learn With Us, week of August 30

Sept. 1, 2 PM on WCOM 103.5 FM – Getting Dirty Radio Show
Last Days of Summer Missed the show on the radio? Listen after the air date on http://gettingdirtyradioshow.org/

Thursday, Sep 3, 2015 6:30pm – 8:00pm
Soil Preparation, Extension Gardener Seminar
Sarah P. Duke Gardens, 420 Anderson Street, Durham, NC, United States
Durham’s native soil is somewhat difficult to work with. Charles Murphy, Durham County Extension Volunteer Master Gardener, will discuss what can be done to make the soil easier for the gardener & more productive for the plants. Remember, time & patience are factors.  Class is free. Registration required. Contact: gardenseducation@duke.edu 919-668-1707
Saturday, Sep 5, 2015 10:00am – 11:30am
Lawn Care, Extension Garden Seminar
Durham Garden Center, 4536 Hillsborough Road, Durham, NC, United States
Maintaining a beautiful lawn in our area is a struggle for many of us. Gene Carlone, Durham County Extension Volunteer Master Gardener, will discuss the pros & cons of cool season & warm season grasses, optimal lawn care for our Piedmont climate & soil. He will introduce you to the best maintenance methods & untangle the confusing range of lawn care products.
Class is free. Registration required. To Register: Sign up at the store or e-mail Ann at ann3dgc@gmail,com or call 919-384-7526

Dig It! The Secrets of Soil

by Andrea Laine

Soil covers one-third of the earth’s surface and, worldwide, it plays a role in agriculture, architecture and construction, art and rituals, medicine, water filtration, climate change and much more.  Did you know that the source of phosphorus in the Amazon rainforest is soils in the Saharan Desert blown across the Atlantic Ocean?  As a critical natural resource soils deserve much more respect than they typically get!

I am not a soil scientist.  But if I were, I’d be proud. That is how fascinatingly interesting I found the subject of soil during a recent visit to Dig It! The Secrets of Soil, an engaging exhibition on display through August 16, 2015 at the North Carolina Museum of Natural Sciences in Raleigh.

Developed in conjunction with the Soil Science Society of America (including several North Carolina soil scientists) and the Smithsonian’s National Museum of Natural History, this exhibition is diverse, highly interactive and informative for all ages.

As gardeners we understand that soils are living (teeming with insects and microbes); soils are varied (more or less pH, more or less organic matter, more or less space between particles for example); soils change (sometimes whether we want them to or not); and soils link land, air and water.

Dig It! explains those points and explores the profound ways soils support our lives well beyond their role in agriculture.  One exhibit focused on common products in a home that rely on soils such as ceramic tile flooring, house paint and fabrics.  Another demonstrated the impact construction projects have on soils.  Others let visitors peer into deep cross-sections of soil to see what it looks like well underground. One massive display included a soil sample cross-section for each of the 50 states. There is also a section about the arts and science of pottery in North Carolina.

The North Carolina Museum of Natural Sciences is located at 11 West Jones Street in Raleigh. It is open Monday – Saturday, 10 a.m. to 5 p.m. (last entry at 4 p.m.) and Sunday, noon to 5 p.m. (last entry at 4 p.m.) Admission to the museum is free and there are free and low-cost parking options nearby.  http://naturalsciences.org/

If you can’t make it to the exhibit, you can watch some creatively educational videos about soils by following this link:  http://forces.si.edu/soils/

Learn With Us, week of Jan. 25

Jan. 27 – Getting Dirty with Durham County Master Gardeners Radio Show, 2pm. Harold Johnson talks to soil ecologist Dr. Nicolette Cagle.  She is a lecturer at the Nicholas School of the Environment at Duke University.  She also directs the Environmental Science Summer Program at Duke, and is a NC Science Leadership Fellow.  Dr. Cagle tells us how to make love, not war with our soil.
Broadcasts Tuesdays at 2:00pm on WCOM 103.5  Can be heard live or replayed any time at http://gettingdirtyradioshow.org
NickiDr. Nicolette Cagle