Bidens subalternans: complete guide

Overview

Bidens subalternans, better known as 'Greater beggar's ticks' or 'picao', is a fascinating annual plant from South America. The plant grows wild from Colombia to northern Argentina. The name 'beggar's ticks' refers to the characteristic seed pods with barbs that cling to clothing and animal hair for dispersal. This is an ancient genus of useful plants.

The plant is interesting for gardeners who appreciate botanical curiosities. Although not native to Europe, it is a medicinal and culinary plant in South America. In the Netherlands it grows exclusively as a summer annual.

Appearance and bloom

Bidens subalternans grows as a fairly slender, branched plant to approximately 80-100 centimeters tall. The stems are angular and greenish to reddish colored. The leaves are nearly alternately planted (hence 'subalternans'), compound and finely serrated. They have a fresh, green color.

The flowers are small, approximately 0.5-1 centimeter in diameter, yellow in color. They appear in fairly large numbers during the growing season. After blooming, characteristic little fruits form. These are very striking, elongated structures with 2-4 barbs at the top. These barbs are covered with fine hairs that easily grip textiles. The fruits are easily dispersed by water and animals.

Ideal location

Bidens subalternans thrives best in a warm, sunny spot. The plant has a strong preference for sunny, with at least 6-8 hours of direct sunlight daily. In half-shade growth will be weaker. Shade is not suitable.

The plant loves warmth and grows better in warm years. It is also quite sensitive to heavy rainfall. A spot with some shelter is therefore ideal, especially against heavy, continuous rain.

Soil

Bidens subalternans is not fussy about soil. The plant grows in virtually all draining soils, though it prefers well-draining, calcareous to neutral soils. A pH of 7-7.5 is ideal.

The plant has no extreme fertilizer requirements. Normal garden soil is sufficient. Heavy clay soils can be improved with sand or compost.

Watering

Bidens subalternans likes regular water, but also tolerates dry periods reasonably well. Give the plant approximately 2-3 centimeters of water per week in normal conditions. Ensure the soil does not completely dry out.

Excessive water can lead to leaf disease. Drip irrigation or morning watering is better than nighttime watering.

Pruning

Bidens subalternans does not really need pruning. The plant grows fairly compact and orderly on its own. You can pinch some tips in July-August to encourage bushier growth. This helps produce more flowers.

Damaged or sick leaves can be removed to promote health.

Maintenance calendar

April-May: Sow indoors or directly outside after last frost. May-June: Transplant and thin out. July: Pinch tips for bushier growth. August-September: Full bloom, start seed collection. October-November: Harvest seeds. Store seeds for next year.

Winter hardiness

Bidens subalternans is not hardy and dies at the first frost. This is truly an annual plant in our climate. The plant, however, grows fast enough to produce seeds before it freezes.

Seed collection in fall is the best way to have the plant again next year. Store seeds in a dry, cool place throughout the winter.

Companion plants

Bidens subalternans combines nicely with other South American annuals. Sunflowers (Helianthus) look good next to it. Tomatillos and other South American food plants form a botanically coherent group.

In an herb garden it can grow together with other medicinal herbs from the same region.

Final word

Bidens subalternans is a fascinating plant for those who want something different. Although exclusively annual in the Netherlands, it provides insight into South American flora. Seeds are available via gardenworld.app and specialized seed merchants. A true botanical adventure for the gardener!