Hitch hikers, Black-jack Seeds

Black-jack (Bidens pilosa) is a fast-growing annual daisy up to 1.8 m tall whose barbed black seeds catch on fur and clothing, which is why it is called hitch hikers.

Also known as: Black-jack, Hitch hikers, Spanish needle, Beggar’s ticks, Hairy beggarticks, Cobbler’s pegs, Farmer’s friends, Devil’s pitchfork, Picao-preto (Portuguese), Amor seco (Spanish), Bident poilu (French).

What you are sowing

• Each seed is a stiff, slightly curved, rough black achene about 1 cm long.
• Most carry two to three heavily barbed awns at the tip.
• The flower heads have four or five broad white rays around many yellow disc florets, and flowering can run most of the year.

Sowing

1. Press the seed onto the surface or cover it only shallowly.
2. Give light and open, well-drained soil in a warm, sunny spot; the plant prefers conditions above about 15 °C.
3. Keep moisture steady until seedlings emerge.

No separate dormancy period has to be broken first. We hold no sourced germination percentage or lot test for this seed, so none is stated here.

Before you sow: limits

The species is native to tropical America and is now a noxious or invasive weed in many warm regions. One plant can set 3,000–6,000 viable seeds, and hand weeding works only while plants are small. Grow it in a container, remove flower heads before the seeds ripen, and check your local rules first.

FAQ

Do the seeds need cold treatment?

No. Seed germinates at the surface or at shallow depth, light and good aeration help, and no dormancy period is required.

How tall does it grow?

Descriptions range from about 90 cm in Florida extension notes to as much as 1.8 m, depending on conditions and where it grows.