Arachis hypogaea (Peanut Plant)

Arachis hypogaea , commonly known as the Peanut Plant , is a unique plant that produces flowers above ground, but its fruits, the peanuts, develop underground, a phenomenon known as geocarpy. This interesting feature makes peanuts a botanical curiosity and a popular subject of study in agriculture. With this characteristic in mind, botanist Carl Linnaeus gave peanuts the specific name hypogaea, meaning "underground".

Peanuts belong to the botanical family Fabaceae (or Leguminosae), commonly known as the legume, bean or pea family. Like most other legumes, peanuts host symbiotic nitrogen-fixing bacteria in their root nodules. The ability to fix nitrogen means that peanuts require less nitrogen-containing fertilizer and improve soil fertility, making them valuable in crop rotations.

Peanuts are valued for their high protein, healthy fats, B vitamins, and essential minerals, making them a nutritious snack and a versatile ingredient in the kitchen. The plant needs a warm climate and well-drained soil to thrive, preferring regions with long, hot summers.

In gardening, Arachis hypogaea can be grown as an interesting and educational addition, providing home gardens with not only useful fruit but also the opportunity to observe a fascinating growth cycle. This plant is relatively easy to grow and can be a satisfying source of its own harvest, adding value and diversity.

Appearance of leaves, flowers and fruits

• Leaves : The leaves are compound, paripinnate, consisting of 2-3 pairs of oval leaflets, medium green , 3-7 cm long. They are arranged alternately on the stems, with a smooth texture and entire margins.
• Flowers : The flowers are small, yellow, typical of legumes, with butterfly-shaped petals, 1-1.5 cm long. They appear in June-July in the leaf axils, being self-fertile, but can attract bees for pollination. After pollination, the floral peduncle (called "peg") elongates and penetrates the soil, where the fruits are formed.
• Fruits : The fruits are underground pods, 2-6 cm long, with a woody, yellowish shell, containing 1-4 seeds (peanuts). The seeds are oval, covered by a thin, reddish shell, and are rich in oil (40-50%) and protein (20-30%). The harvest is done 90-150 days after planting, depending on the variety.

Growth characteristics

• Height and width : Grows up to 30-60 cm tall and 60-90 cm wide , with an erect or creeping habit, depending on the variety (e.g. "Virginia" varieties are erect, "Runner" are creeping).
• Vigor : Moderately fast growth, with branched, slightly hairy stems. The root system is pivotal, with nodules that fix nitrogen, enriching the soil.
• Type : Annual, herbaceous plant, grown in 4-5 month cycles, sensitive to frost.

Growing conditions

• Exposure : Prefers full sun (6-8 hours/day) for optimal development and maximum production. Shade reduces flowering and pod formation.
• Soil : Requires loose, well-drained soil, preferably sandy or loamy, with a slightly acidic to neutral pH (5.8-7). Compact or heavy clay soils prevent the peduncles from penetrating the soil.
• Watering : Water regularly , keeping the soil moist but not soggy, especially during flowering and pod formation (July-August). Reduce watering towards the end of the cycle to facilitate harvesting.
• Temperature : Grows well at 20-30°C , being sensitive to temperatures below 10°C or above 35°C . Hardy in zones 8-11 , requires a warm season of at least 120 frost-free days.

Care and resistance

• Resistance : Sensitive to frost and prolonged drought. Resistant to some fungal diseases, but can be affected by leaf mold (Cercospora) or root rot (Rhizoctonia). Attracts pollinators, but is not resistant to deer or rodents.
• Fertilization : Apply a low-nitrogen fertilizer (e.g. 5-10-15) at planting and during flowering, as the plant fixes natural nitrogen. Excess nitrogen favors foliage at the expense of pods.
• Pruning : No pruning required, but remove weeds to prevent competition for nutrients and space.
• Pests and Diseases : May be affected by aphids, mites, caterpillars or nematodes. Use organic insecticides and crop rotation for prevention. Inspect for mold or leaf spots.
• Propagation : Propagated by seeds (raw, unroasted peanuts), planted 5-7 cm deep, at distances of 15-20 cm, in spring, after the soil reaches 18°C.
• Harvest : Harvest when the leaves begin to turn yellow (September-October), lifting the plant with a fork. Dry the pods for 2-4 weeks in a well-ventilated place.

Use

Arachis hypogaea (Peanut Plant) is grown for its edible seeds , eaten raw, roasted, in peanut butter, oil, sweets or animal feed. It is an important source of protein, healthy fats and vitamins (E, B). The plant is used in agricultural gardens , farms or test crops in home gardens, being attractive for its ability to fix nitrogen. It combines well with corn or cotton in crop rotation. In landscaping, it is rarely used ornamentally, but can be an educational element.

Origin

Native to South America , Arachis hypogaea was domesticated 7,000–8,000 years ago by indigenous peoples of Bolivia and Paraguay. It was spread to Africa, Asia, and North America during colonization, becoming today the second most important oilseed legume after soybean.

Height with pot included: approx. 20 cm
Pot diameter: 12 cm