Thomas black walnut is a deciduous tree in the walnut family (Juglandaceae) and is a hybrid of the native black walnut. The tree grows 40 to 65 feet tall and wide in full sun and average well-drained soils. It is deer and verticillium wilt resistant. The taproot contains juglone, which might inhibit the growth of some plants such as azaleas, peonies, some vegetables like tomatoes, and blueberries beneath the tree's dripline. The spring flowers are followed by large, thin-shelled, easy-to-crack nuts with excellent flavor. Use Thomas as a shade tree in meadow and woodland locations. It also can be used in butterfly, edible, native and nighttime gardens. Diseases, Insects and Other Plant Problems: Under pressure in some areas from thousand cankers disease. Other potential diseases include anthracnose, bacterial blight, root rot, canker, leaf spot and shoot dieback. Watch for aphids, fall webworm and a variety of foliage chewing caterpillars.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; Loam (Silt); Sand
Soil pH
Acid (<6.0); Neutral (6.0-8.0)
Soil drainage
Good Drainage | Moist | Occasionally Dry
Available space
more than 60 feet
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 40 ft. 0 in. - 65 ft. 0 in. | Width: 40 ft. 0 in. - 62 ft. 0 in.
Growth rate
Medium
Maintenance
Medium
Canopy layer
1 - Canopy (>40 ft)
Form & Appearance
Habit / form
Erect; Multi-stemmed; Rounded
Texture
Coarse
Foliage
Deciduous
Leaf color
Green
Leaf type
Compound (Pinnately , Bipinnately, Palmately)
Leaf arrangement
Alternate
Leaf shape
Lanceolate; Ovate
Leaf margin
Lobed; Serrate
Leaf size
> 6 inches long, 3-6 inches wide
Hairs present
No
Leaf detail
Leaves emerge late and drop early; 12 to 24 inches long with 15 to 23 leaflets, ovate-lanceolate and finely serrate. 3-lobed leaf scar resembling a monkey face. Leaves drop sporadically during the season. More ovate, more leaflets, and less serrated margins than pecan. Leafing is in late spring with yellow-green leaves and fall color of bright clear yellow.
Fall color
Gold/Yellow
Flower color
Gold/Yellow; Green
Flower form
Catkin; Insignificant
Flower size
< 1 inch
Flower detail
Single-stemmed yellow-green male catkins are 2 ½ to 5 ½ in long, appearing in axillary buds on the previous year's growth. Female flowers are short-spiked in terminal clusters of two to five on the current year's growth. Flowers from April to May and are wind pollinated.
Bloom time
Spring
Fruit color
Brown/Copper
Fruit type
Nut
Fruit detail
Produces large, thin-shelled, easy-to-crack nuts with excellent flavor.
Bark color
Dark Brown
Bark detail
Brown ridged and furrowed with rough diamond pattern bark. Bark is thick.
Stem color
Brown/Copper
Stem detail
Brown ridged and furrowed with rough diamond pattern bark. Bark is thick.
Wildlife & Ecology
Native status
Unknown
Wildlife value
This plant supports Hickory Horndevil (Citheronia regalis) larvae which have one brood and appear from May to mid-September. Adult Hickory Horndevil moths do not feed. Also a Larval host for Banded Hairstreak butterflies and Luna moth. Meat of the nut is sweet and edible and a favorite food for squirrels.
Attracts
Butterflies; Small Mammals
Host plant for
Banded Hairstreak butterflies and Luna moth
Food & Medicine
Edible parts
Nuts
Harvest time
Fall
Fruit type
Nut
Edibility
Edible nuts
Landscape Use
Landscape location
Lawn; Meadow; Woodland
Landscape theme
Butterfly Garden; Edible Garden
Design feature
Shade Tree
Garden tags
#problem for dogs #nut tree #small mammals #food source hard mast fruit #deciduous tree #allelopathic #edible nuts #full sun #butterfly caterpillar host #shade tree #problem for horses
Problems & Resistance
Insect problems
Walnut Caterpillar
Problems
Allelopathic; Problem for Dogs; Problem for Horses