Wild parsnip in the garden: identify, sow and care

Wild parsnip (Pastinaca sativa) is a native biennial of the carrot family. In its first year the plant makes only leaves and a long taproot. The second year brings a stem 60 centimetres to 1.2 metres tall. Flat heads of yellow flowers open on it from July to September. The species wants sun and moist, lime-rich soil.

Wild parsnip at a glance

Leaf

March to October

Flower

July to September

Fruit

August to October

JanFebMarAprMayJunJulAugSepOctNovDec

How do I recognise wild parsnip?

Start with the leaves. They are yellow-green, and each leaf is divided once, or sometimes twice, into leaflets along one stalk. A single stalk carries 5 to 11 oval leaflets, lobed and coarsely toothed. The upper side is often glossy.

The flowering stem grows upright. Its surface is angular, grooved and covered in short hairs. The whole plant has a distinct smell of its own.

At the top sit flat flower heads, called umbels, on 5 to 20 stalks. The yellow flowers are only one and a half millimetres across. Their petals curl inward at the tip. Flat, egg-shaped fruits of 5 to 8 millimetres follow, each with a narrow wing.

Take note of fennel, which also has yellow flower heads. Fennel leaves are very fine, as thin as thread. Wild parsnip has broad, toothed leaflets. On waste ground you may sometimes find a subspecies, Pastinaca sativa subsp. urens. Its stem is barely grooved near the base, or not at all.

Where does wild parsnip grow best?

Wild parsnip does best in full sun: more than six hours of direct sun a day around midsummer. With three to six hours, partial shade, the plant still manages. In the wild it grows on road verges, on dikes, in rough vegetation and in damp hay meadows.

Three spots in a garden work badly:

• A border you have just manured. Fresh manure or compost makes the taproot fork.
• Heavy, compacted soil full of stones. The long taproot struggles to get through. Loosen the soil first.
• Right beside a narrow path. Walk past in summer with bare arms or legs, and the sap can end up on your skin.

In January, after flowering, only a dry, straw-coloured stem with empty flower heads remains.

JulyJanuaryThe same border in July and in January. This is a generated image, not a photograph.

In the app you can look for a spot away from the path, on a plan of your own plot. That parcel comes to scale from the Kadaster, the Dutch cadastre, with the neighbouring houses drawn in.

Planting and care

Sow wild parsnip in March, April or early May, one centimetre deep, straight into its final spot. A young plant from a nursery works too. Leave about 50 centimetres between two plants, because a single plant can grow that wide. On sowing day that looks like empty ground. The flowering stem needs the space in its second year. Water in dry weeks until the young plants are established.

Beyond that, wild parsnip needs no pruning. Do wear gloves when you work on the plant, especially on a sunny day.

Many bird species nest from March through July. Many have more than one brood and carry on into August. In those months, look around first before you remove a stem.

Common problems with wild parsnip

No flowers appear. In the first year that is normal. For flowers every summer, sow again every year.

The plant dies after flowering. That is part of its life, not a disease. Leave the dead stem until winter.

Nothing comes up after sowing. Wild parsnip is slow to germinate: the seedlings appear only after 14 to 30 days. Old seed germinates poorly, so buy fresh seed every year.

The root has tunnels or brown patches. Those are carrot fly maggots, or parsnip canker, a disease of the root. This matters mostly in a vegetable garden, because there you harvest the root.

Which insects and birds use wild parsnip?

Wild parsnip is a food plant of the swallowtail (Papilio machaon), a butterfly. Its caterpillar feeds mainly on carrot and on other plants of the carrot family. The swallowtail flies in two generations, from late April to mid-September. In the Netherlands the butterfly is fairly scarce and is seen mostly in the southern half.

The white-spotted pug (Eupithecia tripunctaria), a moth, also lives on wild parsnip. Its caterpillar feeds on the flowers and the fruits from mid-May to October. This moth is fairly common, spread across the whole country.

Which birds benefit from wild parsnip has not been well described.

Is wild parsnip poisonous?

Wild parsnip is mildly poisonous, to the skin. The sap makes skin sensitive to sunlight. If sap gets on your skin and the sun then shines on it, the skin can become inflamed. Not everyone reacts this way.