Green Man Publishing

Parsnip

Pastinaca sativa ssp sativa

Introduction: The parsnip has been an important crop since the time of the Romans. It was actually a staple root vegetable in Europe for centuries, until it was eventually displaced by the potato. It is still much more popular there than it is in North America and is a common sight in their vegetable gardens.

Crop value: The parsnip is a valuable crop for several reasons. It tastes good, is nutritious, is easy to store (simply leave it in the ground) and easy to grow. The main drawback is that it is slow growing and in the ground for quite a long time.

Ease of growing: Parsnip is an easy plant to grow, as once established it is capable of looking after itself. When I first started gardening and carrot used to give me problems, I never had any difficulty with parsnip.

Climate: The parsnip is a cool season crop, growing best at 60 – 65˚F. It grows well enough in warmer weather, but warm nights (above 65˚F) cause the plant to use the sugar it produces for further growth, rather than storing it in the root. Such roots won’t be very sweet.

Parsnips are very hardy and can tolerate a considerable amount of frost, which actually improves their flavor by making them sweeter.  

Nutritional content: The root contains carbohydrates, vitamin C, folate, calcium, manganese, potassium and lots of fiber. It is quite a good source of energy with 340 calories per pound.

About Parsnip  
Seed facts
Germ temp: 35 (50 – 70) 85°F
Germination time: 10 – 21 days
172 days / 32°F
57 days / 41°F
27 days / 50°F
19 days / 59°F
14 days / 68°F * Optimum
15 days / 77°F
32 days / 86°F
Viability: 1 year
Germination percentage: 60%+  

Planning facts
Hardiness: Hardy
Growing temp: 40 (60 – 65) 75°F
Plants per person: 25
Plants per sq ft: 9
Direct sow
Spring: 2 wks before last frost
Fall: Sow mid summer
Days to harvest: 120 – 200 days  

Harvest facts
Yield per plant: 2 – 16 oz
Yield per sq ft: 1 – 4 lb sq ft
 

Soil

pH 6.0 – 7.0

The ideal soil for parsnips is a fairly neutral, loose, well-drained, moderately rich loam. It should be deep because the roots may go down 2 feet and also fairly free of stones. They won’t be very productive in poor soil.

 Soil preparation: Incorporate 2 – 4˝ of compost or aged manure into the top 12˝ of soil. Don’t use fresh manure, as too much nitrogen encourages foliage growth at the expense of the roots (it may also make the roots fork). Like most root crops they need lots of potassium (add greensand) and phosphorus (add colloidal phosphate or wood ashes), but relatively little nitrogen. Add lime if the soil is acidic.

If the soil is compacted, double digging is recommended, as it ensures the soil is loose and free of large stones. If it is really bad, you might consider growing the shorter varieties and planting in trenches filled with a special sifted topsoil / compost mix.

Parsnips are a good crop to plant after potatoes. They like the deeply dug soil and the previous heavy fertilization.

Planning

Where: Parsnips do better than most common crops in light shade, though they are more productive in full sun. They are in the ground for a long time, so should be located where they won’t interfere with late garden operations, such as fall bed preparation.

When: Parsnip planting should be timed so the plants mature in the cool weather of autumn. It is quite a long season crop (it can easily take four months to reach maturity) and when you plant it is largely determined by the length of your growing season.

Spring: In areas with a short growing season you plant it in spring for a fall harvest. You can sow the seed as early as 2 weeks before the last spring frost date, but unless there is a rush to get them in the ground, you may as well wait a few weeks until the soil has warmed up. If you look at the germination times you will see that it takes the seed almost 2 months to germinate at 40°F, but only a month at 50°F.

Fall: In areas with a longer growing season they are usually planted in midsummer, so as to mature around the time of the first fall frost. They can then sit in the ground until needed. Start thinking about planting them 4 months before the first fall frost.

Planting

Direct sowing: Parsnip seed is considered to be temperamental and you often read warnings against using seed that is more than one year old. I haven’t had much difficulty in getting 2 year old seed to germinate, but for best results it is best to use fresh seed where possible. You should also plant lots of it (you may as well use the whole packet as it doesn’t keep well anyway). It is better to sow slightly too thickly (and have to thin) than it is to risk not having enough plants.

The seed is quite slow to germinate, taking 2 weeks even at the optimal 68°F. It may not germinate very well if the soil is warm, which could be a problem if you are planting in midsummer. See Lettuce for more on persuading seed to germinate in cool weather.

The most critical aspect of sowing is depth, as the seedlings aren’t very vigorous and must not be sown too deeply (¼˝ is enough). Some people plant a few radishes along with the parsnips under the theory that the fast germinating radishes break up the soil surface, making it easier for the parsnips to emerge (they also mark the rows).

Broadcast sowing: Scatter the seed so there is an inch separating each one. Be careful of high winds blowing the light seeds as they are designed to be scattered by the wind. Also make sure you sow enough seed, because after you plant it might take a whole month before you realize your stand is too sparse. Cover the seed with a thin ¼ – ½˝ layer of soil (or a mix of sifted topsoil and compost).

Row sowing: Sow the seed ½ – 1˝ apart in shallow furrows Then re-fill the furrows with a thin layer of sand, or a mix of sifted topsoil and compost (ideally you want to plant them ¼˝ deep.) You can also sow it in wide rows.

Water gently after sowing. Too much water, applied too quickly, may wash these light seeds around. This results in bare patches and very dense patches, which isn’t good.

Spacing: The distance between plants largely determines how big they can get.

Beds: If you want very large roots space them 4 – 5˝ apart in the beds. For average sized roots space them 3˝ apart.

Rows: Space the plants 2 – 4˝ apart in the row, with 18 – 24˝ between the rows.

Thinning: If the plants are to grow quickly, without competition from neighboring plants, they must be properly thinned. As with carrots, this is one of the most crucial aspects of raising good parsnips.

When all of the seedlings are up and about 3˝ tall, thin them to the desired spacing, taking out the weakest plants where possible. Don’t wait too long to do this, as their roots and tops will soon get tangled.  

Care

 Weeds: The young plants don’t compete with weeds very well, so must be weeded carefully. This should be done by hand, as hoes can easily damage the shoulders of the root. Older plants are able to compete against weeds pretty well, as they produce a dense canopy of foliage.

Watering: Parsnips need constant moisture (especially when the roots are sizing up), so don’t let the soil get too dry. Give them at least 1˝ of water per week.

Fertilization: If the soil isn’t very fertile, give your plants a regular feed of compost tea or liquid seaweed every month.

Mulch: If growing in rows it is helpful to lay down mulch between the rows. It keeps the soil moist, suppresses weeds and covers the shoulders of the roots.

Problems

Pests: Parsnip can be affected by most of the pests that attack the related carrot, but it tends to be a pretty problem free crop and isn’t usually badly affected.

Leaf Miners: The only pest I have encountered has been leafminers, but as we don’t eat the leaves their damage is usually fairly inconsequential. If they get bad, you might want to use row covers.

Canker: This disease is commonest in poorly drained, acid soils and causes the root to rot. Most modern varieties have some resistance to it.

 Harvesting

When: Parsnips generally take around 120 – 150 days to reach maturity. They can be dug any time they are large enough, but they are at their best from late autumn onwards, after the tops have died down and they have been exposed to several weeks of frost and cold weather. Low temperatures cause the starch in the root to be converted into sugar, which makes them sweeter.

Generally the roots are gathered after the foliage has died down and it’s getting cold. As with carrots the young roots are the most tender, but they are not as sweet or tasty as older ones. You can continue to eat parsnips all winter until you run out, or until they start to grow again the following spring (which they do quite early).

How: If the soil is very loose, you can simply pull the roots up by the tops. If the soil is heavy they will just break off if you try this. You then have to loosen them with a fork before pulling. After harvesting you should remove the tops, to stop them draining moisture from the root.

Don’t harvest any more roots than you can use in the next meal, as they store better in the ground. If you still have roots in the ground in late winter, you should dig them all, as they will turn woody and unpalatable once they start growing again.

Storage: Parsnips are one of the best crops for winter use. They are so hardy they can be stored in the ground all winter and dug as required. A thick mulch of straw can be used to prevent the ground from freezing so they are easier to dig (it may also protect the roots).

In extremely cold areas they may be covered with 4 – 6˝ inches of soil and then a layer of mulch put on top of this.

If mice are a problem you may have to lay down wire mesh before you apply the mulch.

The roots can be stored for several weeks in a plastic bag in the fridge.

For long term storage, treat them like carrots and store them in a root cellar, in damp sand or peat moss. Large quantities can also be stored in a clamp (see Potato). Smaller quantities may be sliced and frozen.

Seed saving: It’s easier to save parsnip seed than most other biennials, because they are so hardy there is no problem getting them through the winter. You don’t have to store the roots inside, or even protect them outside (though you might want to move them to a more convenient place).

Parsnips flower in the spring of their second year. They are cross-pollinated by insects, so you should grow only one variety at a time (or you could isolate them). They will also cross with wild parsnip, which is the naturalized wild form of this plant (it is common in some areas). Save seed from at least a half dozen plants to maintain some genetic diversity.

Gather the ripe seeds from the umbels in summer (don’t wait too long or they may start to disperse) and dry thoroughly. They will need at least a month of after-ripening before they will germinate.

Unusual growing ideas

Intercrop: Parsnip is so slow to get started that it is common practice to plant a fast growing intercrop, such as lettuce or spinach, in between the newly sown rows. These will be harvested before the roots need the room.

Greens: The tender new leafy growth of second year plants is sometimes eaten in salads. Surplus roots are sometimes forced indoors to supply early spring greens.

Varieties

Some parsnip varieties can produce large, spindle shaped roots up to 18˝ in length, with a diameter of 3˝ at the top. These larger roots need a very deep and loose soil to perform well.

Most modern varieties are resistant to parsnip canker. The commonest varieties include:

All American

Cobham Improved

Improved Hollow Crown

Harris model

Kitchen use

Parsnips are best known for their use in winter stews and soups, but can be used in lots of other ways too. Try roasted parsnips, French-fried parsnips, stir-fried parsnips, steamed parsnips or baked parsnips.

Baking is particularly good as some of their starch will be converted into sugar and they become very sweet.

When sugar was expensive parsnips were sometimes used to sweeten cakes and to make desserts (and they still can). In Britain they have been used to make a surprisingly good wine.

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