Parsnips

Start from seed: November – January

Optimum soil temperature for germination: 17-23°C

Plant spacing: 10-15 cm

Days to maturity: 90-130 days

Introduction

Parsnips (Pastinaca sativa) belong to the Apiaceae family, which also includes carrots, celery, and parsley. These root vegetables, with their sweet, nutty flavour that intensifies after frost, are a rewarding crop for cool-climate gardeners.

Originally native to Eurasia, parsnips have been cultivated since ancient times, with evidence of their use dating back to Roman times. They were a staple food in Europe before potatoes were introduced, providing an important source of carbohydrates during winter months. Parsnips were introduced to Australia with European settlement and have since become well-established in home-gardens, particularly in cooler regions like Canberra.

The parsnip plant forms a rosette of pinnate leaves above ground, while below it develops a cream-colored taproot that resembles a pale carrot but with a distinct flavour. Parsnips are biennial plants usually grown as annuals for their roots, but if left in the ground, they will produce flower stalks with yellow umbels in their second year. They are nutritionally rich, containing vitamins C, E, K, folate, and minerals such as manganese, phosphorus, and potassium, as well as being a good source of dietary fibre.

Site and soil

Parsnips grow best in Canberra’s cool temperate climate, particularly when planted between November and January for harvest after winter frosts, which enhance their sweetness. They prefer full sun but will tolerate partial shade, especially during the hotter months.

Soil preparation is crucial for successful parsnip growing. They require deep, well-drained soil that is free of stones and large clods. The ideal soil is a sandy loam with a pH between 6.0 and 7.5, slightly acidic to neutral. If your soil is too acidic, add lime before planting.

Prepare beds by cultivating with a broad fork or digging deeply (at least 30 cm) to create a loose, friable growing medium. Prior to planting, incorporate compost and a balanced organic fertilizer. Unlike many vegetables, parsnips prefer soil that is not overly rich in nutrients. Avoid adding fresh manure, which can cause roots to fork. 

For container growing, use pots at least 40-45 cm deep with good drainage. Fill with quality potting mix boosted with complete organic fertiliser. While container-grown parsnips won’t develop as large as those in the ground, they can still produce satisfactory harvests.

For details on preparing soil and pots, including the use of lime, dolomite, gypsum and fertilizers, please refer to the COGS guide to garden bed preparation.

Planting Seeds and Seedlings

In Canberra, parsnips can be sown in November, December and January.) for winter harvest. Direct sowing is essential, as parsnips do not transplant well due to their long taproot.

Parsnip seeds are known for their short shelf life and slow germination. Use fresh seed, less than one year old, and sow thickly. Sow seeds in shallow drills about 1 cm deep then sieve soil over the top to cover lightly. Tamp seed down gently. Rows can be 25-30 cm apart. To improve germination rates, which can be notoriously poor, keep the soil consistently moist. This can be achieved by covering the bed with a hessian sack or old sheet. When watering, just water the sacks or sheet. Some gardeners place a board over the seeded row to retain moisture until germination occurs.

Germination typically takes 2-4 weeks, depending on soil temperature. Once seedlings are established with 2-3 true leaves, thin them to 7-10cm apart to allow proper root development. The thinnings can be composted but are not suitable for consumption at this early stage.

Parsnips are sometimes companion planted with quick-growing radishes, which mark the rows and break the soil surface, making it easier for the slower parsnip seedlings to emerge. The radishes will be harvested long before the parsnips mature.

Cultivation

Parsnips are relatively low-maintenance vegetables once established, but consistent attention to a few key areas will the best results.

Water management is critical, especially during germination and early growth. Keep the soil consistently moist but not waterlogged. Once roots are established, reduce watering frequency aiming for regular deep watering to encourage deep root development. Inconsistent watering can cause roots to split.

Parsnips are not heavy feeders, and excessive fertiliser use can lead to lush foliage at the expense of root development. If the soil was properly prepared before planting, additional fertiliser is generally unnecessary. A light application of a balanced organic fertilizer with low nitrogen content may be beneficial if growth seems sluggish. A monthly foliar spray with seaweed solution; a mix of worm juice, seaweed and compost tea; or trace elements will help boost growth and resilience to pests and diseases.

Weed control is important, especially during the early stages when parsnips grow slowly and compete poorly with aggressive weeds. Hand weed carefully to avoid disturbing the developing parsnip roots, and maintain a light mulch to suppress weed growth and retain soil moisture.

In Canberra’s climate, parsnips grow best during the cooler months, slowing down in the heat of summer. Providing some afternoon shade during hot weather can be beneficial. The plants are frost-tolerant, and their flavour will improve after frosts which stimulate the conversion of starch to sugars.

Harvesting

Parsnips typically take 100-120 days to mature, depending on the variety and growing conditions. 

The roots can be harvested when they reach 2.5-5 cm in diameter at the shoulder. Unlike many vegetables, parsnips can be left in the ground over winter, and harvested as required. However, in heavy clay soils, roots may rot in excessively wet winter conditions, so harvesting before heavy winter rains might be necessary.

To harvest, loosen the soil beside the roots with a garden fork, then carefully lift the parsnips to avoid breaking the roots. If the ground is deeply frozen, cover with straw or leaves for a few days to thaw the soil before attempting to harvest. The long, skinny tapered end often snaps off during harvesting which is most unsatisfying!

After harvesting, twist off the leaf tops about 2.5 cm above the crown to prevent the flesh from becoming rubbery. Parsnips can be stored for several weeks in a cool, humid environment (around 0-4°C). Parsnips should be harvested before spring when they will begin to flower and the roots become woody.

Problems

The best approach is to have a reliable Australian reference book to identify problems. Garden Pests, Disease and Good Bugs by Denis Crawford is recommended.

A general strategy to follow with any problem is to observe the plant carefully before taking action. Identify the problem then carefully consider the course of action. For example, with pest insects, you often can see a predator nearby. If you watch and wait the predator may deal with the problem for you. Beneficial predatory insects which feed on pest insects can be purchased from suppliers such as Bugs for Bugs. If the problem needs further action the above recommended book has suggestions. 

Practicing good garden hygiene, crop rotation, and maintaining plant vigour by providing adequate nutrients are key strategies for prevention.

While generally robust, parsnips can face several challenges in Canberra gardens:

Carrot Rust Fly: The larvae of this pest tunnel into the roots, causing rusty brown tracks and damage. Protect young plants with row covers, delay planting until after the first generation of flies has passed, or use companion planting with aromatic herbs like rosemary or sage to confuse the flies.

Parsnip Canker: This fungal disease causes black or orange-brown patches around the crown and shoulders of the root, with cracking and hardening of the flesh. It’s more common in acidic soils or when roots are damaged. Prevent by maintaining proper soil pH, ensuring good drainage, and practicing crop rotation.

Powdery Mildew: A fungal disease appearing as white powder on leaves, particularly in humid conditions. Improve air circulation around plants and avoid overhead watering. In severe cases, organic fungicides based on potassium bicarbonate can be used.

Forking Roots: This is not a disease but a physiological disorder caused by rocky soil, fresh manure, or soil that is too rich in nitrogen. Prevent by preparing the soil properly before planting, removing stones, and avoiding the use of fresh manure.

Leaf Spot: Several fungi can cause spotting on parsnip leaves. While primarily an aesthetic issue, severe infections can reduce plant vigour. Maintain good air circulation, avoid overhead watering, and remove and dispose of affected leaves.

Warning: When handling parsnip foliage, especially on sunny days, wear gloves and long sleeves. The sap contains furanocoumarins that can cause a severe skin reaction (phytophotodermatitis) when exposed to sunlight.

Recommended Varieties

Several parsnip varieties perform well in Canberra’s climate. All have improved flavour after frost.

Melbourne Whiteskin: open pollinated vigorous strain with excellent, tasty white tapered roots, firm and bulky. 

Dugi Bijeli: old Yugoslavian variety with large, sweet roots. 

Hollow Crown: A traditional variety with long, slightly hollow-crowned roots and excellent flavour. 

Gladiator F1: A modern hybrid with improved disease resistance and uniform, smooth roots. Less prone to canker than some open-pollinated varieties. 

Guernsey: A medium-sized variety with firm white flesh and a nutty flavour. It has good cold tolerance and stores well in the ground over winter. 

White Gem: Produces medium-length roots with smooth white skin and sweet, tender flesh. More tolerant of heavier soils than some varieties. 

Harris Model: An old variety known for high yields and uniform shape. 

References

1. Bubel, Nancy. The New Seed-Starters Handbook. Rodale Books, 2018.
2. Crawford D. Garden Pests, Disease and Good Bugs. Australia: ABC Books; 2015.
3. Dove, Helena. Botany of the Kitchen Garden, Kew Publishing, Royal Botanic Gardens Kew, UK, 2023. 
4. Fanton, Michel and Jude. The Seed Savers Handbook. The Seed Savers Network, Australia, 1993.
5. The Seed Collection. (2024). How to Grow Parsnip Seeds. https://www.theseedcollection.com.au/growguide/parsnip-seeds
6. Yates Australia. (2024). How to Grow Parsnip. https://www.yates.com.au/how-to-grow/parsnip/