Black Walnut
Juglans nigra
America's native nut tree that produces intensely flavored nuts prized by gourmet cooks and wildlife alike. Black walnut combines valuable timber potential with unique culinary nuts that have a bold, distinctive taste unlike any other nut. This impressive native tree creates its own ecosystem space through natural allelopathy while providing generations of harvestable nuts and potential lumber value.
Harvest
180-210d
Days to harvest
Sun
Full sun to partial shade
Zones
4–9
USDA hardiness
Height
50-75 feet
Planting Timeline
Showing dates for Black Walnut in USDA Zone 7
All Zone 7 nut-tree →Zone Map
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Black Walnut · Zones 4–9
Growing Details
Zone-by-Zone Planting Calendar
Complete Growing Guide
Light: Full sun (6 or more hours of direct sunlight a day), Partial Shade (Direct sunlight only part of the day, 2-6 hours). Soil: Clay, Loam (Silt), Sand. Soil pH: Acid (<6.0), Neutral (6.0-8.0). Drainage: Good Drainage, Moist, Occasionally Dry, Occasionally Wet, Very Dry. Height: 50 ft. 0 in. - 75 ft. 0 in.. Spread: 50 ft. 0 in. - 70 ft. 0 in.. Growth rate: Rapid. Maintenance: Medium. Propagation: Seed. Regions: Coastal, Mountains, Piedmont.
Harvesting
Brown to black nut inside a fleshy, non-splitting, yellow-green husk that heavily stains skin and clothing. Displays in October. Nut inside is edible. Fruit attached singly or in pairs, globular, with pointed apex.
Color: Black, Brown/Copper, Gold/Yellow, Green. Type: Nut. Length: 1-3 inches. Width: 1-3 inches.
Garden value: Edible, Fragrant
Harvest time: Fall
Edibility: Nut is sweet and edible. An edible oil is obtained from the seed, but it tends to go rancid quickly. Used as a seasoning in bread, squash and other foods.
Storage & Preservation
Freshly harvested black walnuts should be cured in a well-ventilated space at 60–70°F with moderate humidity for 2–4 weeks until the hulls dry completely and crack away from the shell. Store shelled nuts in airtight containers at 32–40°F; they'll keep for 3–4 months refrigerated, or up to a year frozen. For longer preservation, freezing is your best option—crack and remove the nutmeat, then pack in vacuum-sealed bags or freezer containers. Drying works well for baking applications; spread cracked meats on screens in a dehumidified space until brittle. Black walnuts develop a sharper, more complex flavor after 2–3 months of storage, making them worth the wait if you're using them for gourmet confections or specialty applications. One practical note: the tannins in black walnut hulls stain everything permanently, so wear gloves during processing and cure nuts on a surface you don't mind discoloring.
History & Origin
Origin: Eastern United States, west to Texas, and South Eastern Canada
Advantages
- +Attracts: Moths, Small Mammals
- +Edible: Nut is sweet and edible. An edible oil is obtained from the seed, but it tends to go rancid quickly. Used as a seasoning in bread, squash and other foods.
- +Fast-growing
Companion Plants
Black walnut sorts its neighbors into two groups whether you want it to or not. The sorting mechanism is juglone — a compound the roots and leaf litter push into the surrounding soil — and it's specific enough that you can plan around it once you know the list. Corn, squash, beets, carrots, and onions all handle it without trouble, and mulberry and cherry trees planted at similar spacing coexist fine. Tomatoes, apple trees, pine trees, and alfalfa are genuinely damaged — not just set back a week, but often killed — so keep them at least 50-60 feet from any mature trunk. In a zone 7 Georgia yard where a big black walnut can cast a 70-foot root shadow by the time it's producing well, that spacing constraint shapes your whole garden layout more than any other single factor.
Plant Together
Cherry Trees
Tolerant of juglone toxicity and can grow successfully near black walnut
Mulberry
Shows good tolerance to juglone and complements walnut grove ecosystems
Black Raspberry
Naturally juglone-tolerant and provides understory fruit production
Carrot
Root vegetables generally tolerate juglone well and don't compete for canopy space
Beets
Juglone-tolerant root crop that can grow in walnut tree vicinity
Squash
Shows good tolerance to juglone and utilizes ground space effectively
Corn
Demonstrates natural resistance to juglone toxicity
Onions
Tolerant of juglone and may help deter some soil pests
Keep Apart
Tomatoes
Extremely sensitive to juglone toxicity, will wilt and die near black walnut
Apple Trees
Highly susceptible to juglone poisoning, shows stunted growth and decline
Pine Trees
Sensitive to juglone, exhibits yellowing needles and reduced vigor
Alfalfa
Very sensitive to juglone, shows chlorosis and poor establishment
Nutrition Facts
Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #2346394)
Pests & Disease Resistance
Resistance
Excellent native disease resistance and pest tolerance
Common Pests
Few serious pests, occasional walnut caterpillars, fall webworm
Diseases
Thousand cankers disease in some regions, generally very hardy
Troubleshooting Black Walnut
What you'll see, why it happens, and what to do about it.
Webbed masses of leaves clustered at branch tips in late summer, with leaves skeletonized or brown inside the web
Likely Causes
- Fall webworm (Hyphantria cunea) — caterpillars spin communal webs and feed inside them from July through September
- Walnut caterpillar (Datana integerrima) — feeds in groups, often defoliating entire branches before moving on
What to Do
- 1.On reachable branches, prune out the web and drop the whole mass into a bucket of soapy water
- 2.For larger trees, a spray of Bacillus thuringiensis (Bt) on young caterpillars is effective — older larvae are harder to kill
- 3.One defoliation in a mature tree rarely causes lasting damage; two or three years in a row is when you worry
Scattered branch dieback with dark, sunken cankers on the bark, especially in trees under 30 years old
Likely Causes
- Thousand cankers disease — caused by the fungus Geosmithia morbida, vectored by the walnut twig beetle (Pityophthorus juglandis)
- Historically a western problem, but confirmed moving east — NC State Extension has flagged it as a regional concern worth tracking
What to Do
- 1.Don't move walnut wood, logs, or bark from areas where thousand cankers has been confirmed
- 2.Prune dead branches back to clean wood and dispose of them off-site — don't leave infected material on the ground beneath the tree
- 3.No cure exists once a tree is heavily infected; catching it early and removing affected wood is the only practical management
Nearby vegetable plants — especially tomatoes, peppers, or apples — wilting and declining for no obvious reason within 50 feet of the tree
Likely Causes
- Juglone toxicity — black walnut roots and decomposing leaf litter release 5-hydroxy-1,4-naphthoquinone, which disrupts mitochondrial function in sensitive plants
- The toxic zone typically extends to the drip line plus 50 feet beyond, and persists in soil for years after a tree is removed
What to Do
- 1.Relocate sensitive crops at least 50-60 feet from the trunk — further if the tree has been in the ground more than 20 years
- 2.Raised beds won't protect plants if walnut roots have grown underneath them; the juglone moves with the roots, not just the surface litter
- 3.Stick to tolerant crops in the root zone: corn, squash, beets, carrots, and black raspberries all handle it reliably
Frequently Asked Questions
How long does it take to grow Black Walnut trees from seed to harvest?▼
Is Black Walnut good for beginners?▼
What does Black Walnut taste like compared to English walnuts?▼
Can you grow Black Walnut in containers?▼
What pests should I watch for when growing Black Walnut?▼
How much sunlight do Black Walnut trees need?▼
Growing Guides from Wind River Greens
Where to Buy Seeds
Sources & References
External authority sources used in compiling this guide.
- ExtensionNC State Extension
- USDAUSDA FoodData Central
See the Methodology page for how this data is sourced, what's AI-assisted, and known limitations.