Parkinsonia ACULEATA

Parkinsonia ACULEATA - Jerusalem thorn, Mexican palo verde, Jelly bean tree, Parkinsonia aculeata.

Parkinsonia is a small genus in the legume family (Fabaceae), comprising about a dozen species. They grow in arid regions of the Americas and Africa, on rocky plains, in semi-deserts, and along dry riverbeds.

The plants are spiny shrubs and small trees with green photosynthetic bark and very tiny leaflets that drop quickly during drought.

The flowers are yellow, five-petaled, fragrant, gathered in loose racemes. The fruit is a narrow pod, constricted between the seeds like a string of beads.

Jerusalem thorn is an undemanding plant from arid regions of the Americas that has spread widely throughout the tropics. In nature, it is a tree up to 8–10 m (26–33 ft) high; in a container, it forms an elegant shrub.

The drooping branches are covered with thorns, which, combined with small yellow flowers and feathery dark green foliage, look very ornamental. The leaf is unusually structured: a long, flattened rachis up to 40 cm (16 in) long bears dozens of tiny leaflets, and from a distance the crown appears like a green cloud. The sweet fragrance of the flowers attracts butterflies.

Parkinsonia seeds are large and smooth, with a very dense seed coat, retaining viability for years. Before sowing, scarification is mandatory: the seed coat is carefully filed from the side, away from the embryo. After this, seeds are soaked for 6–8 hours in warm water or in a growth stimulant solution: SUPERthrive, HB-101, Aminosol, Epin, or Zircon. Stratification is not required.

Sowing can be done year-round. Sowing is carried out into a mixture of soil, compost, and sand to a depth of about 1.5 cm (0.6 in). The sowing is moistened from a spray bottle, covered with a transparent lid or placed in a greenhouse, and germinated in light at a temperature of 22–26 °C (72–79 °F).

Seedlings emerge in 1–3 weeks; unswollen seeds may take longer. Sowings are aired daily, condensation is removed, and waterlogging is unacceptable. Seedlings grow rapidly, so pricking out into individual deep pots is carried out immediately after the unfurling of the first pair of true leaves.

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The plant needs an open sunny location; in summer, it is best placed outdoors.

Warm conditions are maintained, ideally 22–30 °C (72–86 °F). In winter, the temperature should not fall below 10 °C (50 °F); an adult plant tolerates brief mild drops in temperature.

Watering is moderate in summer and very rare in winter. Parkinsonia is extremely drought-resistant and suffers far more from excess moisture than from drought.

The substrate should be loose and water-permeable, made of a mixture of soil, compost, and sand. Drainage is necessarily placed at the bottom of the pot.

Fertilizing with a complete fertilizer with reduced nitrogen content is applied once a month from spring until the end of summer.

The shoots are thorny, so pruning and repotting are more comfortably performed with gloves. Formative pruning is well tolerated and carried out at the beginning of active growth.