Pecan, Pecan Tree: Planting, Growing

Description and Botany

The Carya illinoinensis, pecan or pecan walnut is a fruit tree from the Juglandaceae family, like the walnut (Juglans regia). It is native to the humid forests and swamps of North America, specifically Illinois, Kansas, Missouri, Texas, Virginia, Kentucky and northern Mexico. Despite its good hardiness, its cultivation is best suited to Mediterranean regions as it requires long, hot summers to bear fruit. The Carya genus includes 25 species, of which the most widely cultivated is Carya illinoinensis, which produces delicious pecan nuts. This species has given rise to various varieties such as ‘Choctaw’, ‘Delmas’, ‘Amling’, ‘Gloria Grande’, ‘Amling’ or ‘Sumner’, which vary in growth, productivity, nut size, precocity and disease resistance.

The pecan is a large tree with deep roots. Its growth is fairly rapid, forming a handsome tree with an upright habit and rounded crown. It can reach 20 to 40 m in height and 10 to 15 m in width, with a trunk circumference of up to 6 m. Some varieties like ‘Mohawk’ have a more modest growth, reaching around fifteen metres in height. The grey, furrowed bark is decorative, peeling off in strips over time.

The pecan or pecan walnut has deciduous foliage. The alternate, odd-pinnate leaves, borne on long petioles, can measure up to 50 cm in length and consist of 9 to 13 oblong leaflets. Green in spring, they turn golden in autumn just before falling. They emit a rather unpleasant odour when crushed.

Carya illinoinensis: habit (© James St John) and autumn foliage (© Forest and Kim Starr)

Flowering is prominent in spring, from March to May. It occurs in two stages. Just before the leaves emerge, in late March, long, pendulous yellowish-green male catkins measuring up to 15 cm in length appear, hanging along the branches. They consist of small flowers with 6 petals.

Later, inconspicuous female flowers emerge in small upright spikes at the tips of young shoots. These are heavily visited by pollinating insects, which freely fertilise them. However, this fruit tree is partially self-fertile, so it is preferable to have two trees to ensure effective cross-pollination, as the male catkins do not mature at the same time as the female flowers. Fruiting begins around the 4th or 5th year. It is a biennial-bearing tree, producing nuts every other year.

Flowers, foliage and fruit of Carya illinoinensis

After fruiting, the tree produces oblong, fleshy drupes 4 to 6 cm long, green in colour, turning brown at maturity, called husks. These inedible, dehiscent drupes are grouped in clusters of 2 to 10. They split open at maturity into 4 valves to release a smooth, elongated brown shell. Inside this stone, once shelled, lies a bilobed almond measuring 3 to 6 cm in length, edible and delicious: the pecan nut, also called hickory nut. It contains white flesh covered by a thin reddish-brown skin. Nut size varies by variety. Harvest occurs from August to November. These smooth kernels have a taste similar to walnuts and almonds, but without the bitterness of traditional walnuts. Their flavour is more refined and less astringent.

The United States and Mexico account for nearly 95% of global pecan production. The pecan is cultivated both for its nuts and for its high-quality wood, used in veneer.

Husk and pecan nuts

Main species and varieties

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[product sku=”1003561″ blog_description=”A very good productive variety yielding large-calibre walnuts. Less imposing than the type species but equally ornamental.” template=”listing1″ /]

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Planting the Pecan Tree

Where to Plant a Pecan Tree?

Hardy down to -15°C, even -20°C depending on the variety, the pecan tree can be grown throughout France as an ornamental plant. However, to obtain fruit in our latitudes, it is preferable to reserve its cultivation for Mediterranean regions. It will not thrive north of the Loire. This is a fruit tree that develops better in warm climates. However, it requires both fairly cold winters to induce flowering and long, hot summers followed by mild autumns for its walnuts to ripen, with at least 6 to 7 frost-free months. Nevertheless, newer varieties tolerate shorter and cooler summers.

The pecan tree appreciates semi-moist soils and grows naturally in fertile, well-drained floodplains. It has fairly high water requirements in summer. If the summer is too dry, ensure it is watered accordingly, although once well-established, its taproot allows it to draw moisture from deep within the soil.

Plant it in a very sunny location in rich, moist to wet, well-drained, even sandy soil so it can spread its root. Quite demanding, it dislikes prolonged droughts and neither overly dry nor too chalky soils, preferring a rather acidic substrate with an ideal pH between 4.5 and 7.5.

It naturally fits in an irrigated orchard in Mediterranean areas but also in ornamental gardens as a standalone specimen in open ground within a short grass meadow thanks to its elegant silhouette and spring flowering. Given its mature size, allocate space proportionate to its significant growth. The largest specimens are best suited to large wooded gardens or parks. And carefully consider its placement, as its taproot dislikes transplanting.

Growing in a very large pot is possible, though it will naturally remain smaller in size and is unlikely to bear fruit. You’ll enjoy its ornamental qualities more than its fruit.

A magnificent pecan tree in a large garden (© Forest and Kim Starr)

When to Plant the Pecan Tree?

Planting is best done in spring, between February and May, outside frost periods.

How to Plant It?

In open ground

Its powerful root system means the soil should be well-prepared to a depth of about 1 m and equally in width. Maintain a distance of 10 to 50 m between two pecan trees or other trees, depending on their mature spread.

• Soak the root ball in a basin of water
• Dig a planting hole 1 m in all directions
• Mix 1/3 heather soil, 1/3 horticultural sand, 1/3 garden soil
• Add a few spadefuls of sand and gravel to ensure good drainage around the roots
• In overly acidic soil, add dolomite or ash
• Pour part of the mixture into the hole
• Insert a stake and tie the trunk with a flexible tie to support it in the early years
• Place the root ball without damaging the taproot, leaving the collar level with the soil
• Fill gaps with the remaining mixture
• Firm down and water generously
• Mulch the base

My tip: topping the tree at this stage, by pruning a third of its height, will encourage new root development.

In a Pot

• Choose a container with drainage holes, holding at least 100 litres (1 x 1 m)
• Add a drainage layer (coarse sand, clay pebbles, pumice)
• Partially fill the pot with good horticultural compost mixed with horticultural sand
• Place the root ball and fill around the roots with compost
• Firm the surface well
• Water generously

Cultivation and Care of the Pecan Tree

Vigorous and low-maintenance, the pecan tree thrives with minimal care, requiring only regular watering, especially during drought and extreme heat. It has high water needs. For the first 6 months after planting, watering should be frequent and regular: provide between 30 and 50 litres of water per week. Once the tree begins to bear fruit, after 5 years of cultivation, watering becomes crucial: ensure it is watered generously every day to allow the walnuts to ripen.

Spread a thick layer of mulch made of dead leaves, straw, wood chips, or partially decomposed compost to suppress weeds, keep the roots cool in summer and warm in winter.

Apply organic fertiliser in spring, such as well-rotted compost lightly worked into the surface, or a special fruit tree fertiliser. Pruning is not necessary.

Diseases and potential pests

Hardy, it is mainly susceptible to certain fungal diseases such as powdery mildew, or bacterial leaf scorch which affects the foliage. As a preventive measure: spray the leaves with Bordeaux mixture after rainfall. It may also be affected by crown gall which impacts the entire root system, fortunately newer cultivars show resistance to these diseases.

When and how to harvest pecan walnuts?

You’ll need to wait 4 to 5 years for the pecan tree to bear fruit after planting. The harvest spans from mid-August to mid-November, more commonly around November, depending on the variety’s precocity, the summers, and your region. Pecan walnuts are simply harvested by hand or they will be shaken to dislodge the fruits from the branches.

→ Learn more in our tutorial Harvesting and Storing Pecan Walnuts: Our Tips.

Preserve and use pecan nuts

Dried pecan walnuts can be stored for about a year, just like walnuts. Freshly shelled pecans quickly turn rancid when exposed to air. You can keep them in airtight jars at room temperature or refrigerate them in closed containers for 6 months. Alternatively, freeze them in freezer bags where they will keep for 1 year, though the cold may diminish their flavour.

They can be enjoyed fresh or dried on trays, arranged in a single layer in a cool, dry, and well-ventilated place. Pecan walnuts can be used as halves, caramelised, roasted, ground, blanched, or as oil. They are perfect as appetisers, snacks, or in pastries. They add a delightful crunch to the famous pecan pie. They pair wonderfully with chocolate in brownies and cookies!

→ Learn more in Solenne’s tutorial: Harvesting and Storing Walnuts

Pecan pie, brownies, appetisers… in the kitchen, they work for sweet or savoury dishes!

What are the benefits of pecan nuts? (Note: The term "noix" was translated as "nuts" in this context, as "pecan nuts" is the common British English term for "noix de pécan". The botanical name remains unchanged.)

This oleaginous shell fruit is rich in lipids, particularly polyunsaturated fatty acids such as omega-9 (oleic acid) and omega-6 (linoleic acid). Pecan walnuts have a low glycemic index and a low sugar content. Packed with potassium, magnesium, zinc, and phosphorus, they make a real anti-fatigue cocktail, are good for immunity, and help balance the nervous system. Rich in antioxidants, they reduce cholesterol levels and prevent cardiovascular complications. They are energy-dense, containing approximately 700 kcal per 100 grams.

How to propagate Carya illinoinensis?

Sowing in spring is the easiest way to propagate Pecan trees but you’ll need to wait 10 to 12 years to obtain fruit. The tree can also be propagated by shield grafting in summer. This is a relatively delicate operation for amateur gardeners, and we recommend leaving it to professionals.

By sowing

• Fill deep pots with a light mixture composed of 1/3 heather soil, 1/3 loam, 1/3 perlite
• Sow the pecan seeds on the surface, then cover them with 2 to 3 cm of substrate
• Maintain in a humid environment at 20°C until germination
• Remove the plastic cover
• Repot into a larger container then transplant into the garden when the young plant is sufficiently rooted