Tag Archives: Home & Garden Column

Charcoal as a Soil Amendment

This article first appeared in The Times-Herald Record on Saturday, May 11, 2019 in the Home & Garden section.

By Joe Gregoire, Orange County Master Gardener, Cornell Cooperative Extension Orange County

I’ve heard that adding carbon to the soil by mixing in charcoal is good for plants.  Is this correct?  Jessica from Monroe

burning wood in a fireplaceGreat question, Jessica.  And as I’ve just recently cleaned out my fireplace from the winter and wondered if I could use the ash in my garden, I’ve done a little research on the topic that I’ll share with you here.

There is a long history to the practice of adding ash and charcoal to soil and is a proven method of soil improvement.  The pre-Columbian Amazonian peoples developed an understanding of the importance of soil carbon as they worked to meet their agricultural needs in their hot and humid rain forest environment.  Their warm, wet climate created conditions in which soil organisms quickly decomposed organic material – that was then absorbed into the rapidly growing rainforest flora.  When rainforests are cleared and plowed, this soil is quickly depleted of soil carbon and susceptible to erosion, making food production difficult to sustain on the same land for more than a few years.  However, archeologists have found that ancient Amazonian cropland contains large deposits of dark, rich soil called Terra Preta that was made by these ancient farmers between 2,500 to 4,000 years ago.  This Terra Preta contains high amounts of charcoal created through the process of pyrolysis (burning organic material in high heat and low oxygen) which preserves up to 50% of the carbon vs. converting it into CO2 gas through complete combustion.  Pyrolysis produces a very porous and stable form of organic matter through physically and chemically altering the composition of the biomass being burned.

pile of charcoal bitsUniversity studies have shown that adding charcoal (also called Biochar) to soil increases the soil’s water-holding capacity, reduces soil density, improves soil structure, and has been proven to reduce soil nutrient leaching and increase crop growth. Pre-packaged biochar can be purchased from retailers today or can be made at home by buying or building a biochar kiln for home use.  Many low-cost designs can be found online and enable the conversion of biomass (wood) into charcoal to amend the soil.  Biochar can be produced from a variety of materials – trimmings from woodland and yard maintenance, agricultural waste like corn stalks, and purpose grown biomass such as bamboo. The pH and composition of the biochar that is produced is directly linked to the material used to produce the biochar, so if making your own, be sure to avoid contaminants such as treated or painted lumber.

Biochar has many properties that have potential to enhance soil fertility and is a highly stable form of organic matter, as the 4,000 year-old Terra Preta demonstrates.  Organic matter in soil is important for retaining moisture and building soil structure through aggregation, which also provides pore space for drainage.  Soil organisms depend on this balance of air and water in soil to survive and thrive. With increased soil life comes increased soil nutrients to feed your plants.

If you have access to fireplace ash, this can be another ready source of charcoal and other beneficial soil amendments.  Wood ash is a good source of potassium, lime, and micronutrients (which are taken up from the deep roots of hardwood trees used for firewood, such as oak and maple).  It is best to add ash to the compost pile rather than directly to the garden, as the high concentration of lime can alter soil pH and may burn sensitive plants.  The alkaline nature of wood ash can also have a neutralizing effect on compost, as the decomposing materials in a compost pile can become somewhat acidic.  Do not use ash from a charcoal grill, as this ash may contain chemical residue from lighter fluid.

Because of the alkaline nature of wood ash, avoid using it around acid-loving plants such as azaleas, rhododendrons, and blueberries.  Wood ash can also be used as a natural repellent for pests such as snails and slugs who will resist crossing a line of wood ash laid around their favorite plants (the salts in wood ash are an irritant to these soft-bodied pests).  The wood ash needs to be reapplied after a rain or watering to remain effective.

Carbon in the soil is the key to soil life.  Growing plants exude carbon into the soil through their roots in the form of sugars produced through photosynthesis.  These exudates attract and feed beneficial bacterial, fungi and other microorganisms that live and die in the area surrounding plant roots, providing plants with nutrients they need to be healthy.  Our addition of carbon to the soil, in the form of charcoal, can provide additional material for this symbiotic relationship to play out in our garden soil.  And in doing so, we can play an important role in removing carbon from the air and returning it to the soil through our everyday love of gardening.

Click on the graphic below to learn more about soil health!

How can you improve your soil health? A link to an interactive infographic that explores soil management practices, soil helath benifits and soil organsim functions. (Sustainable Agriculture Research & Education - SARE).
An Interactive Exploration of Soil Health and How to Improve It

To learn more about the benefits of biochar and current research on biochar visit:

Biochar – Cornell University

Biochar and Compost Facilities – Cornell University

Terra Preta de Indio – Cornell University

To learn more about using wood ash as a soil amendment check out:

Best Management Practices for Wood Ash as Agricultural Soil Amendment – University of Georgia

Guide to Using Wood Ash as an Agricultural Soil Amendment – University of New Hampshire

Wood ashes can benefit gardens and lawns – Oregon State University

Growing Shiitake Mushrooms in your Backyard

This article first appeared in The Times-Herald Record on Saturday, March 30, 2019 in the Home & Garden section.

By Joe Gregoire, Orange County Master Gardener, Cornell Cooperative Extension Orange County

I love mushrooms and heard that Shiitake mushrooms can be grown on logs in my backyard.  Do you know anything about that? – Phil from Campbell Hall

Happy Spring, Phil.  Yes, I do know something about growing mushrooms on logs.  In fact, Cornell offers a weekend course they call “Camp Mushroom” that is a great way to learn a lot on this subject.  I attended the course a few years ago and have been enjoying fresh picked shiitake mushrooms ever since.  A warning to you though, this is something that requires a lot of patience, so if you don’t mind developing something over a 12-month period, then read on.

Five shiitkae mushrooms growing on a log
Shiitake mushrooms growing on a log

Shiitake mushrooms gathered off fallen logs have been the most popular mushroom in Asia for centuries. The origins of shiitake cultivation have been traced back thousands of years to China and Japan.  People often found these mushrooms growing on downed “shii” trees (this is where the mushroom got its name).   They would take the mushroom-clad logs, place them next to logs without mushrooms and simply wait for the wind to disperse the spores. Thankfully, since then, a lot of research in Japan and China has gone into shiitake-growing techniques, and we don’t have to wait for the wind anymore.  Shiitake is the second most produced mushroom in the world, following the common button mushroom and contribute about 25% of total yearly production of mushrooms. Commercially, shiitake mushrooms are typically grown in conditions like their natural environment on either artificial substrate or hardwood logs, such as oak.

There are several steps to growing shiitake mushrooms on logs.  The first step is purchasing an inoculum which contains the mushroom cells (called mycelium) that will produce the mushrooms.  It most commonly comes in 2 forms – inoculated sawdust, and small wooden dowels that have been inoculated with mycelium.

The next step is obtaining logs for inoculation.  There are many ways to obtain logs.  You can cut your own as you maintain your forest and landscape by thinning trees or pruning large branches.  Or you can contact a local arborist or tree service to see if they can sell you some logs instead of feeding them into a chipper.  Existing commercial shiitake growers in the area may also be able to sell you logs from their own supply.

Leaves of a sugar maple (Acer saccharum)

Shiitake grow best in Oak or Maple trees.  White Oak and Sugar Maple are the proven best producers, with Red Oak a close second.  Red Maple is also considered good.  These dense hardwoods provide the shiitake mycelium a long-lasting food source, which can enable the log to continue fruiting for 3-4 years.  Also, the thick bark layer and durability of the bark on Oak and Maple helps maintain moisture levels in the log and the health of the mycelium.

Leaves and acorn of a white oak (Quercus alba)

Logs are best harvested while dormant.  The bark is tightest during this time of year and timing allows for colonization to be complete in time for the earliest fruiting 12 months later.  Avoid harvesting during spring bud break as bark can slip off during this growth phase of the year.  Select logs that are 4 to 6 inches in diameter about 3 feet long.  Thinner than this will have a shorter useful lifespan and larger than this will be very heavy.  Use only healthy living trees.  This is important in order to ensure that your shiitake spawn is the only species growing in the log.  Let logs season for about 2 weeks after harvest.  It’s conventional wisdom that this seasoning time allows the natural fungal inhibitors in the living tree to dissipate.  Complete the inoculation process within 2 months to ensure logs don’t over dry – 35% moisture content is the ideal – and to avoid competing fungi colonization.


A quick word on safety. 
It is never safe to pick and eat just any random mushroom you find.  Some can make you sick and some can kill you.  It is important to understand a few safety tips to ensure the mushrooms you grow and harvest are safe.
By inoculating only logs from healthy living trees, you give your shiitake spawn a big head start in colonizing the log.  Shiitake are primary decomposers, so they only will grow in freshly cut wood, not already decomposing wood where other mushroom strains may have already colonized.  If you’re not sure if a mushroom on your log is a shiitake, consult a mycologist or other specialist.  Two good local sources are Mid-Hudson Mycological Association and Catskill Fungi.

So now you have your logs – time to inoculate them with shiitake spawn.  Inoculation is a 3-step process:

Step 1 is drilling holes into the logs in a diamond pattern in 6” intervals in rows 2” apart.  The drill bit you use needs to be sized to fit the dowel or the sawdust spawn inoculation tool you’ll be using.  5/16” for dowel and 7/16” for sawdust.  For beginners, I recommend using dowels as only a hammer is needed to pound them into the holes and you avoid buying an expensive inoculation tool.

Step 2 is filling holes with spawn, which is simple with dowels that are pre-inoculated with shiitake mycelium and just need to be tapped into the holes.

Step 3 is to dab melted cheese wax over the filled holes.  Cheese wax is best as it stays pliable for the several years you’ll be harvesting from the log.  The wax replaces the bark and helps maintain moisture in the log.  No need to apply wax to the end of the logs.

pile of shiitake mushrooms
Shiitake Mushrooms

Once the logs are filled and waxed, its just a matter of letting the logs sit for 12 months in a shaded damp space to mature.  The mycelium you placed in the logs will grow during that year and when the weather warms above 60 degrees next spring, shiitake mushrooms will begin to fruit from the log.  And the great thing about shiitake is that you can force them to fruit by soaking the mature log in cold water for 24 hours, which will cause fruiting within about 5 days.  With practice, one can average ¼ to ½ pound of fresh shiitake per log and, after a resting period of 7 weeks, that same log can be forced continue with the same log for 3-4 years until the mushroom has completed the primary decomposition of the log.

Cornell provides a wealth of additional information and tips on this subject, so if you’re interested in learning more, visit http://blogs.cornell.edu/mushrooms/

Here is a link to “Best Management Practices for Log-Based Shiitake Cultivation in the Northeastern United States” put together by Cornell University and the University of Vermont.

Becoming a Master Gardener Volunteer

This article first appeared in The Times-Herald Record on Saturday, February 16, 2019 in the Home & Garden section.

By Joe Gregoire, Orange County Master Gardener, Cornell Cooperative Extension Orange County

What made you decide to become a Master Gardener Volunteer and how do I know if the program is right for me?  – Jackie from Port Jervis

A vegetable garden: leeks, trelised cherry tomatoes, rosemary, parsley, marigoldsI love this question and I’m asked often why I became a Master Gardener.  As I’m a mid-career professional with a full-time job that occupies much of my time, people I work with are often curious how I have time and energy during the week to devote to volunteering as a Master Gardener.  The training program took time to complete and in exchange for the education, all participants in the program give back more time through volunteer work throughout the year.  So, instead of using my limited free time doing whatever I want, I make time to give back to the community.  For me, its about passion.  I’m passionate about gardening and have been from a very young age.  And I have my Dad to thank for that.

One Saturday morning when I was seven, I came home from little league baseball to find the backyard and woods behind our house bull dozed into a large cleared field.  Dad apparently had plans to start a vegetable garden and I wasn’t in the loop.  Not that Dad needed my input, I was a little kid after all.  But had I known what was coming, I could have removed my Matchbox cars from the sandbox the day before.  I didn’t, and the bulldozer turned them into little treasures that would pop up in random parts of the backyard for years to come.  And since I no longer had a sandbox to play in, playing in the dirt became the next best thing.  And Dad made good use of me playing there, putting me to work weeding and watering, while quietly planting seeds in me that would grow into the deep passion I have for gardening today.  The miracle of watching a tiny seed sprout and transform into a growing plant in a matter of days still gives me that sense of awe that is so rare in this busy world.

I find that carving out some of my free time to help share this passion and plant seeds in others like my Dad did for me, is rewarding beyond measure.  While it takes my time, it gives me back energy, joy and relationships within my community I would not have otherwise.  Sure, training for the program also expanded my gardening knowledge, but more importantly, it connected me to resources within the Cornell Extension office.  I’ve used the training and resources to help expand my gardening hobby into a small farm business.  And I’ve found opportunities to volunteer my time that help me hone skills I use in my full-time career, such as creating new presentations, public speaking, and writing articles (like this one).

Three Master Gardener Volunteers staff an "Ask a Master Gardener Table" a
Master Gardener Volunteers answer questions and provide information to the public about a wide range of topics varying from composting to bed bugs.

So, what exactly is a Master Gardener Volunteer?  The Master Gardener Volunteer Program is a national program of trained volunteers who work in partnership with their county Cooperative Extension office to provide home and community gardeners with research-based information and skills. In Orange County, Master Gardener Volunteers assist with gardening projects in the community, teach classes and workshops, work in school and community gardens, provide information at public events, and answer gardening questions through the Garden Helpline.

Who Becomes a Master Gardener Volunteer?  Master Gardener Volunteers are adults of all ages, abilities, and backgrounds. They range from having no professional gardening or landscaping experience, to very experienced gardeners. They all share a genuine interest in making the world more vibrant and livable through gardening.  Master Gardener Volunteers are students, teachers, moms, dads, grandparents, working folks, retired people, and anything else you can imagine.  All you need is a love for gardening, some time to volunteer, and a willingness to complete the training.

Master Gardener Training is completed locally in Middletown.  Cornell Cooperative Extension Orange County will hold its next training class for Master Gardeners starting in September 2019 and running through March 2020.  The training will be held on Thursdays from 9:00 am until 4:00 pm.  Applications will be sent out to interested individuals in the beginning of March 2019 and will be due back on April 19th, 2019. After applications are reviewed, interviews will be conducted in early May and final selections will be made.  All applicants will be contacted by early August and notified of their standing.  The training cost is $300.  Scholarships are available.

If you are interested in becoming a Master Gardener Volunteer or want to learn more about the program, please contact:  Susan Ndiaye, Master Gardener Volunteer Coordinator, sgn32@cornell.edu, (845) 344-1234