Walnut care — light, water, toxicity and hardiness
Walnut (Juglans regia) wants full sun and a drink about every 7 days once established. It is hardy in USDA zones 5 to 9. It is toxic to pets — worth keeping out of reach.
| scientific name | Juglans regia |
|---|---|
| family | Juglandaceae |
| category | tree |
| plant type | perennial |
| light | full sun |
| water cadence days | 7 |
| mature height cm | 2500 |
| min zone | 5 |
| max zone | 9 |
| frost tolerant | true |
| toxic to pets | true |
| toxic to humans | false |
| edible | true |
How often should I water Walnut?
Juglone in the roots suppresses tomatoes and others nearby.
Is Walnut toxic?
Mouldy hulls are toxic to dogs.
Who eats it
Palatable to browsing animals such as deer: low. Palatable to grazing animals: low. Palatable to people: yes.
What it needs
Its shade tolerance is high. Its moisture use is high. Its drought tolerance is medium. It wants at least about 28 inches of rain a year. Above roughly 45 inches of annual rain it struggles. It tolerates soil down to pH 6.0. It tolerates soil up to pH 7.5. Its fertility requirement is medium. Adapted to coarse, sandy soils: no. Adapted to medium, loamy soils: yes. Adapted to fine, clay soils: yes. It needs at least 190 frost-free days. Its tolerance of chalky soil is medium. Its fire tolerance is low. Fire resistant: no. It has been recorded down to -8°F. It suppresses neighbours chemically: yes.
How it grows
It grows as a single stem form. Its growth rate is rapid. Its lifespan is moderate. It puts on most of its growth in spring and summer. It spreads by seed at a slow rate. It resprouts after damage: yes. Coppices: no. Its tolerance of hedging is low. At maturity it reaches about 60.0 feet. By twenty years it is about 25 feet. Its roots go down at least 40 inches. Its shape is rounded. It holds its leaves through winter: no.
What it looks like
It blooms in mid spring. The flowers are white. Conspicuous in flower: no. The foliage is green. The foliage texture is coarse. In summer the canopy is dense in porosity. In winter it is porous in porosity. Fall colour: no. The fruit or seed is brown. Fruit begins in summer. Fruit finishes by fall. It fruits high. The fruit persists on the plant: yes. The fruit is conspicuous: yes.
Growing more of it
Propagated by seed: yes. Propagated by cuttings: no. Propagated by container: yes. Propagated by bare root: yes. Propagated by bulb: no. Propagated by corm: no. Propagated by tubers: no. Cold stratification required: yes. Seedling vigour is high. Commercial availability: routinely available.
Source: Drafted from US Cooperative Extension horticulture guidance; pending HUMAN-05 review (issue 280) · ASPCA Toxic and Non-Toxic Plant List · 2026-09-02