While there are several species of walnuts, particularly black walnuts and English walnuts, the planting and basic care instructions are all similar. However, because of the hundreds of variations that are adapted to different climates and resistance to disease, growing beans in relatively close areas is recommended. The walnut tree can produce delicious nuts and attractive, long-lasting wood, but the home gardener should know that it often kills nearby plants! You can grow walnut trees from the nuts, which are usually free to collect but tedious to prepare, or from seeds, which usually have to be purchased but generally have a higher success rate.
Part 1 of 3: Preparing Walnuts for Planting
Step 1. Understand the effort required, and the risks to your garden
Preparing walnut seeds can take months of waiting, and success rates are low. You can choose to buy seeds and skip to that section instead. Before using any method, be aware that walnut trees, especially the black walnut species, release chemicals in the soil that can kill nearby plants, including pine trees, apple trees, tomatoes, and others. This, as well as their large size and sometimes aggressive spread of new walnut plants, make them unpopular in urban and suburban areas.
Step 2. Collect the fallen walnuts
In the fall, collect nuts that have fallen from the walnut tree, or gently hit the trunk of the walnut tree with a PVC pipe which will cause the ripe nuts to fall. Even after ripening and dropping, most nuts are still encased in the thick green or brown skin that surrounds the nut shell.
- Warning: Walnut shells can stain and irritate skin and clothing. Waterproof gloves are recommended.
Step 3. Alternatively, buy walnuts
If you intend to start a walnut garden to produce walnuts or wood, ask your local forest ranger or search online for species and varieties specific to your climate and intentions. Ideally, purchase walnut seeds from trees within 100 miles (160 km) of your planting location, these are usually more adaptable. Walnuts typically grow in USDA hardiness zones 4-9, or areas with minimum temperatures of -30 to +30ᵒF (-34 to -1ᵒC), but some varieties are more adapted to cold than others.
- Black walnuts are very expensive and sought after for their wood, whereas English walnuts (also called Persian walnuts) are usually grown for both nuts and wood. There are many variations of each, as well as other species.
- Walnuts from a regular store don't have the moisture needed to breed. Even if they do exist, these nuts are likely produced by hybrid trees or tree varieties suited to different climates, making them less likely to be successful in your area.
Step 4. Remove the skin (optional)
Walnuts can grow without their skin removed, but many people remove the skin to check that the walnuts inside are not damaged, and to make them easier to handle. To remove the skin, soak the walnuts in a bucket of water until the outer shell is soft, waiting up to 3 days for the toughest nuts. Crack and peel off the skin by hand.
- Once the skin has dried, it is almost impossible to remove. Try running over it with a car.
- For more walnuts, pop them in a corn sheller, or even rotate them in a cement mixer with gravel and water for 30 minutes.
Step 5. Keep the beans moist in winter, for 90-120 days
Walnuts, like most other plant seeds, need a cool, moist environment before the plant wakes up from its dormancy and emerges from the shell. It takes 3-4 months for the walnuts, depending on the variety, during which time they should be kept moist. Storing seeds in a den. environment
- Store small amounts of walnuts in moist peat or moist sand, in a plastic bag stored in the refrigerator, or in another location between 34 and 41ᵒF (-2-5ᵒC).
- For large quantities of nuts, dig holes in fast-draining soil, 1-2 feet (0.3 to 0.6 meters) deep. Fill this hole by layering a layer of nuts with a 2 inch (5 cm) layer of sand, leaves, or straw. Cover the hole with a sieve to keep out rodents.
Part 2 of 3: Growing Walnuts
Step 1. Take the seeds that germinate a week before they germinate, but make sure to keep them moist
Once the soil has thawed, and at least 90 days have passed, remove the seeds from their cool environment. The live seeds should have small sprouts sprouting out. Make sure the seeds are moist for a full week before planting.
Step 2. Choose a planting location
All walnut species require high-quality soil, and this step is especially important if you are just starting out with a walnut garden. Choose a location with loamy, well-draining soil at least three feet (0.9 m) deep. Avoid steep slopes, hills, rocky soil, and heavily muddy soil. The area lower than the north-facing slope can be used in hilly or mountainous terrain (or facing south, if located in the Southern Hemisphere).
Walnuts are very versatile when it comes to soil pH. Soils between 6.0 to 6.5 pH are best, but anything between 5 and 8 should be acceptable
Step 3. Clean the location
Remove existing plants from the site before planting, as they will compete for the same nutrients that the walnut or tree needs. For garden-sized plantings, cultivating the land and aerating the soil is also recommended.
Step 4. Plant the walnuts in a small hole
Dig a small hole, about 2-3 inches (5-7.5 cm) deep, and place the walnuts sideways underneath, then backfill with soil. When planting more than one tree, place the holes 10-12 feet (3.0-3.7 m) apart, in a grid position.
- Optionally, you can plant two or more beans in one place, 8 inches (20 cm) from each. After the seedlings have grown for a year or two, remove all but the healthiest from each spot.
- See the tips section for alternative planting methods to protect it from squirrels and other small animals.
Step 5. Nurture the growing seedlings
The next section contains information on nurturing seedlings and growing trees. Skip the steps that include planting trees from seedlings.
Part 3 of 3: Planting and Caring for a Walnut Tree
Step 1. Select a seedling (if not growing from a bean)
Measure the seedling diameter 1 inch (2.5 cm) above the root neck, where the roots meet the stem. Choose seedlings with a minimum diameter of inch (0.64 cm) and preferably larger. This is the most important measurement in predicting quality.
- Bare rooted seedlings, sold without soil, should be planted in early spring, before shoot growth, and should be planted as soon as they are obtained.
- Seedlings in containers can be planted later and in drier soil, but are usually more expensive.
Step 2. Plant the seedlings in the spring
Choose clay that drains easily, avoiding steep slopes and hills. Place the seedling in a hole that is twice as wide as the diameter of the seedling's roots, and deep enough to bury the roots. For best results, fill with one part compost for every three parts regular soil. Tamp down the soil and water thoroughly.
Place seedlings 10-12 feet (3.0-3.7 m) apart to accommodate tree growth
Step 3. Water regularly
For at least the first two years after planting, whether grown from nut or seed, walnut trees need additional watering, especially in dry or warm climates. Give the plant a thorough watering, but don't water again until the soil is dry. Watering too often can harm the plant.
After two or three years, the tree only needs to be watered in the hottest season or in times of drought, or one to three times a month
Step 4. Treat weeds
Nurture seedlings by ensuring the surrounding area is free of grass plates and weeds, which will compete with the growth of small seedlings. Remove grass plates and weeds by hand or by placing a weed barrier made of cloth. Larger seedlings can be kept with straw to keep out weeds, using them about 2 or 3 inches (5 or 7.6 cm) above the root zone.
Do not use straw on plants that are not yet out of the soil, as this can hinder sprout growth. Wait until the seedlings grow and have developed roots
Step 5. Learn how to prune walnuts
If you are growing walnuts for wood, it is very important to prune early to ensure a straight trunk, leaving one trunk (leader) at the top of the tree and guiding it straight and upright during another growing season or two. Young trees grown for nuts can be left after thinning, but subsequent pruning is preferable for black walnut trees, as these will usually be sold later for wood, even nut varieties.
- If you have never prune a tree before, especially a sapling, seeking an experienced pruner to help you identify important leaders and trunks is advised.
- If the top of the tree is fork-shaped, bend the best leader straight and tie it to another branch for support, then cut off the end of the supporting branch to prevent growth.
Step 6. Thin the tree set to select the best example
Most gardens start with more plants than the area can support. Once the tree is large enough and the stalks start to collide with each other, choose the healthiest tree that displays the characteristics you want, usually a straight trunk and fast growth. Eliminate everything else, but avoid emptying too much space as this could lead to weeds or even competition tree growth.
You may want to use a crown competition formula to help make your decision
Step 7. Only apply fertilizer once after the tree has grown past the size of a sapling
Fertilizer is a bit controversial, at least for black walnuts, because it can help weeds more than trees if the soil is already rich in nutrients. Wait until the stem is “pole”, or at least 4 inches (10 cm) in diameter and 4.5 feet (1.4 cm) off the ground. Ideally, send the soil or leaves to a forestry laboratory to identify appropriate nutrient deficiencies. If this is not possible, apply a fertilizer containing 3 lbs (1.3 kg) of nitrogen, 5 lbs (2.2 kg) of super phosphate, and 8 lbs (3.6 kg) of muriate of potash to each tree in late spring. Leave some trees without fertilizer to compare the effects, and if positive, reapply every 3-5 years.
Test the soil pH after fertilization to see if you need to readjust it back to normal levels
Step 8. Control pests
Squirrels are very often seen in walnut groves, and can take up a whole walnut harvest if not controlled. Cover the trunk with a plastic tree guard to prevent it from climbing, and prune branches less than 6 feet (1.8 m) off the ground if you can afford to do so without compromising the value of the wood. Other pests such as caterpillars, ticks and flies vary depending on the area, and may not harm your tree if they are active at the end of the growing season. Consult a local forester or experienced walnut grower for information specific to your area.
Keep livestock away from walnut trees of any size, as the damage they can do can render the wood on mature trees worth nothing
To protect the walnut plant from small animals, place the nuts in a can. First, burn the iron can so that it disintegrates within a few years. Remove one end, and cut an X-shaped opening at the other end using an engraver. Place 1 – 2 inches (2.5 – 5 cm) of soil in the tin, bury the beans, and bury the can with the X side above 1 icni (2.54 cm) below the soil. The walnuts will be protected and will germinate through the top of the can
- If the harvested nut is allowed to dry out, or removed before stratification is complete, it may take an additional year to start growing, or fail to grow at all.
- Walnut leaves spread chemicals that kill other plants. Collect and compost until completely destroyed to make it safe to use as hay.