PLANT SPOTLIGHT: Black Walnut (Juglans nigra)

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Black Walnut (Juglans nigra)

Tree Facts

Black Walnut  (Juglans Nigra) is a perennial, stone fruit tree native to Eastern North America, commonly found in riparian zones (area between water and land).  Technically the walnut produces a fruit called a “drupe” and is not a true nut! The drupes are harvested in the fall, dehulled and dried to allow the nut meat to cure for consumption.  This tree can grow very large, eventually reaching over 100’ in height and 6’ in diameter. The black walnut is a member of the Juglandaceae family. Careful consideration should be made before planting or growing around this tree as it is allelopathic, suppressing growth of many other plant species by releasing a chemical called juglone. The black walnut contains the highest concentration of juglone in the nut hulls, roots, and leaves and is commonly used as an herbicide.  This tree has numerous uses, such as: nutritional, medicinal, dye, structural/decorative, antibacterial, and herbicidal.

Seasonal Care-

The black walnut tree grows well between zones 5a-9a.  Commonly found natively near water, these trees prefer deep rich soil, moist yet well drained. Black Walnut is self fertile, but puts on a better fruit set with two trees. It is generally easy to grow with little attention needed.  

Winter/ Spring: Pruning is generally not necessary. Compost or organic fertilizer can be added in the Spring to maximize nut production.

Summer: The first year, a Black Walnut tree should be irrigated every week with 3-5 gallons of water. Once established, the tree generally only needs watering during severe drought.

Fall: Fruit is generally harvested from the ground, dehulled and allowed to dry for a few weeks before cracking the nut and consuming/storing the nut meat.

Nutritional Benefit:

Black Walnuts are packed with nutrients and are considered a superfood.  They contain one of the highest protein contents of any nut (7 grams per serving), as well as high levels of Manganese, Omega-3, antioxidants and other nutrients.  The nutritional content supports metabolism and bone structure, and can help protect against cardiovascular disease, diabetes, and certain neurodegenerative conditions.

Propagating Black Walnut Trees:

As previously noted, Black Walnuts are toxic to a variety of plants and research should be done prior to planting to understand the effects that Black Walnut will have in that area.  Black Walnuts are best propagated by seed, collecting the fruit in the fall dehulling and immediately placing 5-6 whole nuts, 5-6” in the ground. Protect the nuts from animals, by placing chicken wire or cloth over the nuts and securing to the ground.  Cover with leaves/mulch and be sure to properly label location. In the spring remove the protective cover and water the sapling every week with 3-5 gallons of water.

Processing Black Walnuts for Nutmeat

  • Pick nuts up off the ground as soon as possible by hand or nut wizard. It is best to process nuts while the hull is mostly green to avoid mold and astringent nutmeat.
  • Use gloves to handle and de-hull the nuts. They will stain your fingers. They will also stain concrete for a period of time, clothing, and other surfaces.
  • Remember that walnut hulls halve a chemical called “juglone” that suppresses the growth of certain plants, so be mindful of where you take your hulls and wash water
  • Remove green hulls with hammer, knife, or strong hands (some people step on them or even drive over them covered in a tarp!). If hulls are too tough to work, let soften for a few days or buy a de-huller!
  • If you encounter worms when removing hulls, do not be alarmed as they do not affect the nut meat inside the inner shell
  • Rinse de-hulled walnuts to remove debris however you wish. A simple method is to fill a 5-gallon bucket with water and agitate a batch of nuts with a hoe, cement mixer, or by hand three times. Discard nuts that float, a legendary sign of likely spoilage.
  • Spread cleaned nuts out in a single layer to dry for 2-4 weeks. Make sure you do this in an area that squirrels absolutely cannot get to, as they will find a way to steal your nuts. Squirrels broke into Michael’s outdoor solar dehydrator this year because the openings didn’t have thick enough wire mesh! Some people swear that forced heat drying black walnuts at 95-100 deg F for 3-4 days is best for flavor and storage. Turn the shells every so often throughout the drying process.
  • Dried nuts can be stored in shell in a cool, dry location. They can be also be frozen until ready for use. Shelled nuts can be stored in a fridge or freezer for longer shelf life, and salt brining with further dehydration is a way to store walnuts longer at room temperature.
  • To crack black walnuts, do not use a regular nut cracker. It will break. Use a nut cracker that is made for black walnuts, or use a vice grip, or hammer with good hand eye coordination. You’ll want a nut pick or small scraping device to remove the nut meat from the cracked shell.
Volunteers de-husking black walnuts at a POPharvest gleaning workshop at The Woodlands in West Philadelphia.

Black Walnut Recipes!

  1. Basic Black Walnut Pie 
  2. Black Walnut Hummingbird Cake (Cream Cheese Frosting)
  3. Black Walnut Cinnamon Ice Cream
  4. Black Walnut Fudge 
  5. Black Walnut Chicken Quiche 

**Click HERE for more delicious black walnut recipes!!**

Processing Black Walnuts for Dye, Wood Stain, and Ink

  • Add green hulls to a stainless steel pot of water (We used the first rinse water from the above process).
  • Simmer for at least 30 minutes. For darker colors simmer longer, add more hulls, and even boil down the liquid.
  • Cool the liquid and strain through muslin bag or other cloth.
  • Test the strength of the dye/stain/ink. If darker color desired, return to step 2. Be careful not to scorch the liquid if boiling it down.
  • Store liquid in a glass jar or bottle, and add 100 proof vodka or rubbing alcohol (up to 1:4 ratio) to prevent mold and preserve for later use. The liquid will mold after a while if untreated.
  • Experiment with tie-dye or other fabric dying methods, black walnut as a wood stain, and as ink! Fabrics dye a cocoa brown and do not require a pre-mordant for dye to set as with other dyes. Wood stain is a light brown that can me made darker by concentrating the liquid.
Black Walnut tie-dye and wood-staining demos at POPharvest workshop.

Black Walnuts as Medicine

Black walnut hulls contain very powerful medicine that has been used for a variety of conditions including intestinal worms in humans and animals, while it must also be approached with caution. It is also a natural source of iodine. Do not attempt to use black walnut medicine without first consulting professional medical practitioners and clinical herbalists.

This POP Blog was written by 2018 POP Intern Greg Hample and Orchard Director Michael Muehlbauer with assistance from Admin Assistant Natalie Agoos. 

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Fresh Figs for Cold Climates

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One of the wonder’s of Philadelphia’s fine fruit-growing climate is that we can grow certain warmer climate crops like the fig. South Philly is full of decades old fig trees brought over by immigrants from Italy and other Mediterranean countries. These trees were probably coddled in their youth, wrapped every winter as fig-growers still do in Brooklyn and other northerly regions. South Philly’s figs now grow unprotected, often untended, and fill entire back yards with little attention. Our climate has actually become more suitable for figs in recent years as a result of the urban heat island effect and the onset of global warming.

Figs in a South Philly front yard.

Figs are a great crop for Philly for several reasons: taste, productivity, and ease of care.  Many of you have probably enjoyed dried figs, but few have had the pleasure of fresh, ripe fig.  Most of the folks I’ve planted figs with in my work the Philadelphia Orchard Project ( have come no closer than a Fig Newton.  A fresh fig of good variety is a truly sublime fruit, bursting with flavor and texture.  People always point to the difference between a garden tomato and a store-bought one as a reason to grow your own vegetables.  I would posit an equivalent contrast between the experience of a fresh fig and a dried one.

Fresh figs are juicy, flavorful, sublime.

Another reason to grow figs is their relative ease of care.  Apples, pears, cherries, peaches and all the common tree fruits suffer from a wide variety of pest and disease problems.  Figs are generally problem free and require relatively little in the way of pruning, watering, fertilizing, or other maintenance.  In a good year, a single mature fig tree can produce 40 lbs of fruit!  Figs are also beautiful plants: their large lobed leaves create a lush Mediterranean feel.


There are over a thousand species of figs (many Ficus are quite common as houseplants), but only two are grown for their edible fruit: Ficus carica and Ficus sycamorus.  Three types of Ficus carica are grown in the United States.  Smyrna Figs are the most commonly available, grown commercially in California but not at all adapted to colder climes.  The San Pedro Fig can be grown in the north, but requires pollination and generally also necessitates container growing.  The Common Fig is both self-fertile and the best adapted to growing in Philly and other cold climes.  There are dozens if not hundreds of named varieties of Common Figs, varying greatly in taste, color, and growth habit.  The varieties that do best in the north are generally very vigorous growers that can survive some winter damage or pruning and still produce the next season.  Bassem Samaan (, a fig collector and grower from Bethlehem PA, recommends the following varieties for the Northeast: Hardy Chicago, Celeste, Dark Portuguese, LSU Gold and Brooklyn White.  Brown Turkey is the most commonly planted hardy fig, but in general its taste is considered somewhat inferior.

Figs come in many colors, shapes, and sizes- even striped!


Figs need full sun (6+ hours) for good fruit production.  Once established, they are pretty drought tolerant and require little additional watering except during prolonged droughts.  Figs also require minimal fertilizing, although a little compost in the spring can be helpful.  Figs produce their main crop in late summer and fall.  Brushing the fruit with olive oil apparently can hasten the ripening process.  If you successfully overwinter branches of the common fig (Ficus carica), they can also produce a smaller ‘breba’ crop in early summer.  Although birds, insects, and diseases are generally not a concern, squirrels can be sometimes be a competitor for the fruit.

Protection from winter cold is the primary issue in fig care for Philly and other northerly climes.  With proper attention, figs have been successfully grown outdoors in Chicago and Boston.  I’ve also seen them thriving in unheated greenhouses at 7200′ above sea level in Colorado.  There are four primary strategies for overwintering figs in our climate: microclimates, mulching, wrapping, and container growing.


The easiest way to overwinter figs in cold climes is to take advantage of microclimates.  In brief, microclimates are small changes in temperature created by features of the local landscape.  These can occur on scales ranging from a city to a small corner of a yard.  Although Philadelphia is officially in climate zone 6b, the urban heat island effect (all the pavement and brick absorb heat and keep the city several degrees warmer than surrounding areas) results in much of the city being zone 7 in actual practice.  This large microclimate means that other measures may not be necessary to protect figs in the more central and southerly parts of the city.  That said, better safe than sorry, especially in the case of young figs!  In terms of smaller scale microclimates, the best strategy is to plant your fig next to a south-facing wall, which will absorb sunlight during the day and re-radiate the stored heat at night.  A site protected from wind can also make a difference (it’s often wind-chill factor that can take our climate from fig-friendly to one  resulting in winter dieback).  With the right combination of microclimate features, it should even be possible to grow pomegranates and other zone 8 plants in Philly.


Very old espaliered fig at Kew gardens: Beautiful Espaliered, Espalier Trees, African Trees, Espaliered Fig, Kew Gardens, Espalier Fig Tree, PhotoA south facing wall is the best spot for a fig.


There are several techniques for protecting figs with mulching.  The simplest is just to put down a heavy layer of mulch (fallen leaves, salt hay, wood mulch) around the base of the fig tree to protect the roots.  Temperatures below 15 degrees will likely winterkill the branches, but the fig will happily regrow from its roots and often fruit in the same year.  The proprietors of Russell Gardens ( in Southampton PA, about an hour north of Philly, have been using this technique successfully for many years.  Mulching can also be used to protect branches.  On a young tree the branches can simply be bent to the ground, pinned, and then mulched.  On older trees, you can prune out the oldest, stiffest branches and bend the rest to the ground.  You can also sever the roots on one side of the tree with a shovel and then bend the whole tree over to the ground on the over side.  Mulching your figs does come with one caveat: rodent damage has sometimes been reported.


What they do in Brooklyn, Queens, West Philadelphia, Chicago too. . . Many folks from Italian neighborhoods in South Philly and elsewhere will remember the sight of fig trees wrapped in the winter.  Despite the warming trend over the last couple decades, recent harsh winters have shown that this is still an important technique to reduce winter damage and ensure a harvest.  There are many successful approaches to wrapping.  The easiest and best strategy is to trim the fig to somewhere under 6′, tie all the branches together, and then wrap with an old carpet and a tarp.  We also frequently use a length of fencing (at least 3′ high and 10′ in length) filled with fall leaves and preferably covered by a tarp.  Wrapping is generally done when cold arrives in November and removed when it warms in March.

fig protection


Fig cozily wrapped for winter.



Figs are a great container plant.   As is generally the case, growing in containers requires a little more watering and other care than growing in ground.  Figs are best grown in large 15 to 20 gallon containers, although it is certainly possible to have success in smaller ones.  Once they have grown out to fill their container, you will need to repot and root prune every third year or so.  This is best accomplished in late winter or early spring before growth has begun.  Winter protection is as easy as moving the containers into a cellar or unheated garage after their leaves have dropped in fall.  Temperatures in the storage area should not go below 25 degrees or exceed 50 degrees Fahrenheit (you want them to stay dormant).  While they are dormant, the figs will need minimal watering, only every 3 weeks or so.  Bring the figs back outdoors in the spring after the threat of freezing weather has passed.  Container growing allows folks to grow figs on patios, decks, rooftops, and safely in places with contaminated soil!

Container grown fig on a porch in West Philly.

This article originally written by POP Executive Director Phil Forsyth for