English walnut trees can be propagated by growing them from seed or by taking cuttings.
From seed
- Collect seeds: In the fall, collect seeds from the ground.
- Test viability: Put the seeds in water for about a minute. Seeds that sink are viable and should be planted.
- Stratify: Put the viable seeds in a cold stratification period for 70–120 days.
- Plant: In early spring, plant the stratified seeds 2 inches deep in a prepared seedbed.
- Care: Water the seedlings when needed and keep the area free of weeds. In mid-July, fertilize with a slow-release fertilizer.
- Select strongest tree: In the first year, remove all but the strongest-growing tree.
From cuttings
- Take cuttings: Between June and August, take healthy cuttings from young shoots on the tree.
- Prepare cuttings: Cut off the tip of the shoot after 15 cm.
- Plant cuttings: Put the cuttings in a planter with nutrient-rich soil.
- Care: Place the cuttings in a warm, protected spot with indirect sun. Water regularly, but avoid waterlogging.
English walnut trees can also be propagated by grafting, but this is usually only done by professional gardeners.