How to Grow & Harvest Walnuts

About 15 species of walnut tree grow worldwide, including six species native to and growing throughout North America. When selecting a cultivar, you should keep in mind not only the amount of nuts produced by the tree but the ease of cracking. Home growers, according to the University of Missouri Center for Agroforestry, often prefer trees with nuts that are easily opened instead of trees that produce large yields. Walnut trees begin producing quickly and you can expect your first harvest seven years after planting with significant harvests beginning at about 10 years.

Walnut seedling

Pruning shears

Shovel

1-gallon bucket

Bleach

Screen or drying rack

Clear the planting site of weeds and grass, extending the cleared area 1 1/2 to 2 feet around the seedling. You will need to continue to control weeds for three years after planting. While walnut trees produce their most abundant yields when they don't compete with lawn grass, keeping lawn grass in place reduces erosion and reduces weed competition.

Trim off one-third of the tree's top growth, remove any dead or damaged roots and prune the taproot back to 24 inches, if needed.

Dig a hole large enough to accommodate the spread of the seedling's roots without bending them.

Place the seedling in the hole at the same depth it grew in the nursery, allowing for the normal spread of the roots and refill the hole with soil. Do not use any fertilizer or amendments in the planting hole. Press down the soil and water the tree thoroughly after planting to remove air pockets.

Mulch around the seedling, leaving 1 to 2 inches around the trunk clear.

Press your thumb into the husk to determine ripeness for harvest. If your thumb leaves an indentation, the nut is ready.

Pick up nuts off the ground. Commercial growers use tree shakers but, in the home garden, harvesting from the ground is most practical. Harvest often to prevent pest problems and to maintain a good nut color.

Remove the hull. If the hull is stubborn, a bench vise can help remove it.

Mix 1 tsp. bleach into 1 gallon of water and wash the nuts by agitating the water to remove any remaining hull pieces. Discard any nuts that float to the surface.

Spread the nuts on a screen or drying rack to dry. Using forced air will hasten drying, but you should never use warm air.

You can start walnut trees from nuts or seedlings, but seedlings have a higher success rate. Choose a seedling that measures at least 1/4 inch in diameter 1 inch above the roots.

Select a site with deep, well-drained soils. The tree's roots should penetrate at least 3 feet in order to ensure a productive crop of nuts. Walnut trees can thrive in slightly acidic to slightly basic soils, but you should have a soil test done before planting to correct any pH or nutrient problems. Avoid low sites that may act as frost pockets, as late frosts can destroy a nut crop.