How to grow parsnips and best varieties

Modern varieties of parsnips have been bred to produce short fat roots rather than long tapering ones. We were looking for varieties with a good crop of unblemished, smooth-skinned roots, making for little waste in the kitchen.

How to grow parsnips: month by month

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Best parsnip varieties

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When to sow

March to April is the best time to sow parsnips, although you can sow as late as May (which may work best in colder areas.)

To grow good parsnips you will need a deep, stone-free and free-draining soil, preferably sandy. If your soil isn’t suitable, consider growing in raised beds filled with sieved soil to give a depth of at least 20cm. Like carrots, parsnips need little in the way of nutrients. Don’t grow them on freshly manured ground or the roots will fork. 

Seed must be fresh, but even then it can be slow to germinate. Be patient: mark the rows and weed carefully. Sow the seed thinly and thin out excess seedlings to leave one every 7.5-10cm. An alternative is to sow a couple of seeds at this spacing and snip off all but the best seedling. 

Timing is tricky. Though it’s tempting to sow early, the soil may not be warm enough some years. Water the seed bed to promote even germination. Thereafter, don’t water the surface so that the roots are encouraged to go down in search of moisture.

Cover the bed with fine insect-proof mesh to keep out carrot fly.

Mark where you've sown with Best Buy plastic-free labels

How and when to harvest

Harvest in: July to April

You can start to harvest roots as soon as they reach 2cm across, from July or August onwards, but leave the majority for Christmas and winter. The roots should start to taste sweeter after a couple of frosts. Use a fork to lift the roots without breaking them.

Parsnips will remain in good condition in the ground until March or April, when they will start to regrow. As a biennial, a parsnip will produce a huge flowerhead in its second year. In a severe winter, cover the row with straw or several layers of fleece; alternatively lift your crop and store in paper sacks in a cool but frost-free place. 

Try our Best Buy frost protective covers

Common growing problems

Carrot root fly

The larvae of carrot fly can burrow into the roots and cause damage so protect your plants by growing them under fine insect-proof mesh.

Read more about carrot fly

Parsnip canker

Black or orange patches on the roots are a sign of parsnip canker. The patches usually occur near the shoulder of the roots and the crown of the plants. In severe cases, the roots crack and rot. 

The rusty-brown rotting roots caused by carrot fly can be confused with parsnip canker. Look for the tunnels and possibly maggots. Rots caused by sclerotinia don’t usually develop on roots in the ground, but can do on ones in store. The fluffy white mould and associated resting bodies are quite different from canker.

Once the canker has started there is no way to reverse the effect. No amount of watering, liming or fertiliser will have any effect. Once an attack has been detected, use up the roots as fast as possible. Ideally, harvest roots immediately and store in damp sand. Don’t let debris get back on to the vegetable plot. Clear away all crop remains in the spring. This reduces the amount of disease organisms in the soil.

Improving drainage, by putting in drains, double-digging to destroy compacted soil and making raised beds, will reduce the severity. Improving drainage can be difficult on clay soils however. Adding soil improver will improve the soil structure, which in turn enhances drainage. Although it is often said that manuring causes fanged or forked roots, there is no evidence this is the case.

If your soil is acidic, add lime to raise the pH to 6.5. If you don’t know the pH, cheap testing kits are available.

Canker-resistant varieties are available – 'Avonresistor' and 'Cobham Improved Marrow' were the first. Most of the more recent varieties are F1 hybrid varieties and have have some degree of resistance including, 'Albion', 'Archer', 'Gladiator', 'Javelin', 'Palace', 'Panache' and 'Picador'. They should always be used where canker is a problem. They are the most cost-effective control measure although cannot be guaranteed.

How we test parsnips

In spring we selected a range of widely available varieties – most, but not all, modern F1 hybrids (the offspring of crosses between selected parent strains) 

The seed was sown direct into prepared ground at our test site in early April . A row, 5m long was sown of each variety. 

A second sowing of 1.5m length was made in May and a third sowing was made in late May into 30L pots. 

The seedlings were thinned to leave a plant every 7.5-10cm and kept irrigated through the summer. 

We left the plot uncovered to see how resistant to carrot root fly the varieties were. 

The roots were lifted in mid-November by spade to avoid damage.