How to Grow Parsnips
Why grow parsnips?
They taste good! Once started they don't need much care. There is a long harvest time from late summer right into late spring of the next year. Not a lot of pests seem to attack them.
Starting the parsnips
The key to growing parsnips is getting good seeds. They must be fresh. Old seeds will not come up. Some of the newer varieties, often hybrids, have a better record of germinating. I use Park Seed Albion Hybrid Parsnip Seeds The link is for Amazon. Albion is a hybrid which has good germination and is resistant to disease.
Since the roots can be as long as a foot or more, you want to prepare your soil quite deeply. Like other root vegetables a lighter soil works better. If your soil is really heavy then find a shorter stumpier variety.
Parsnips should be sown directly in the ground. Parsnips don't like cold wet feet so don't sow them in cold wet weather, otherwise they will rot before germinating. Wait till the ground has warmed up, experts say 10-12C.
If you are very impatient to see them come up earlier use cloches or little plastic greenhouses to keep the soil warm.
I grow mine in raised beds, planted directly in late May. I planted them around the time I planted the beans who also like their soil to have a chance to warm up. Depends on the year, this year it will be later. I went in and thinned the plants (and ate the ones I pulled out) after the photo was taken.
Even the newer hybrid varieties are slow to germinate so don't give up and don't let the soil dry up.
You will want to plant more seeds than you need plants because they are not always good at coming up. Once they are up you can easily thin them out. They want at least 4 inches between them.
Because they are slow to come up you can sneak in some radishes or green onion sets in between the rows and by the time the radish are ready to eat, the parsnips will be starting to peek out. (You hope.)
Keep an eye on the watering. Your parsnips can tolerate some dryness but if the soil is too dry your parsnips will be woody. I've set up an automatic drip system so that all I had to do was weed occasionally.
Some plants go better with parsnips: Peas, potatoes, beans, radish and garlic are all recommended. Avoid carrots because they will attract the carrot fly with the little grubs that can also infect parsnips. Celery and Celeriac are not good companions nor are the caraways, parsley, or fennel. These last ones attract the lovely black swallowtail with their fabulous but very hungry caterpillars.
I always plant a good number of marigolds and garlic in the garden. They tend to discourage nematodes and deer and bunnies don't seem to like them much either so they form a bit of a barrier.
It's better to delay harvesting till later in the fall. A bit of frost will cause some of the starch to become sugar and your parsnips will taste better, much sweeter. You can brush off the dirt, cut the leaves off, and keep the roots in cool damp, not wet, sand, or peat as you would carrots.
I tend to just go and dig up a few as I need them until the soil freezes. Come spring they will still be good and you can enjoy parsnips again fresh from the garden.
Parsnips all winter long
Parsnips roots are not damaged by frost and on warm days when the ground is not frozen, they can be dug up and enjoyed. Photos above are of parsnips in my garden in mid February and in April. They were sweet and tender. In my garden, I pick parsnips late in the fall as long as the ground can be dug up. I also pick them in the early spring. These along with Jerusalem artichoke and kale can provide garden food when everything else is brown and dead.
Pests and problems
Black Swallowtail have been known to eat parsnip leaves. In my garden they are welcome and I would rather have the lovely black butterflies than parsnips. Luckily the butterflies and their gorgeous green and black caterpillars, prefer the fennel that I plant for them, so they have not been a problem. I think that the caterpillars are quite easy to spot and pick off if you want to.
During the summer I have a great number of wasps that patrol the garden. I encourage them by growing lots of flowers. The adults seem to feed on flowers eating pollen and nectar, but lay their eggs on caterpillars so baby wasps eat the caterpillars. I never kill wasps unless they decide to build a nest in a place that would put me or my family in danger. The wasps are very effective in controlling many garden pests.
Carrot flies lay their eggs in the crown of the plant and the larva burrow in the root and damage the parsnips. They are more likely in carrots but they can infect parsnips. Once the little grub has damaged the carrot, it is more likely to rot.
To avoid carrot flies, don't plant your carrots or parsnips in the same spot 2 years in a row.
Carrot flies are not good fliers and they can be discouraged by putting an 18 inch high mesh barrier around the carrot or parsnip patch.
I plant garlic, onions and marigold around them. It seems to discourage them. I'm told radish is also a good companion but I don't know.
Beneficial nematodes (Steinernema spp.) are sometimes used to control Carrot flies.
In some years the little voles that live around here seem to develop a real hankering for the carrots, parsnips and also for the potatoes. I'll dig up a plant and find only half a root. In my garden, the cats seem to mostly take care of the voles. It helps to sprinkle used kitty litter around the raised beds. This also keeps the squirrels out of the garden ... mostly.
You can sort of see the little teeth marks in the parsnip. Once they've been partly eaten the parsnips are more likely to rot. I don't mind sharing but it's annoying to find several roots all nibbled a little.
Canker is a fungus infection that causes your parsnips to rot. Often it starts at the crown. Some varieties are more resistant than others so check the labels if that's a problem for you. To avoid it, rotate your crops and don't plant your parsnips in the same place as last year. Don't plant them where carrots were either.
When you are harvesting a parsnip be careful not to damage it's neighbours. Be careful when you are weeding too.
Drought and wet soil have been mentioned as increasing the chances of Parsnip Canker.
Don't put the leaves and rotten parsnips in your regular composter. Heating the separate compost under plastic in the sun for several weeks will help kill bad guys. This is called soil solarization.
Toxicity of Parsnips leaves and shoots.
Like many other plants, some parsnips and other members of the Apiaceae can produce toxic compounds, particularly in their leaves. These are furanocoumarins. These are irritating substances that the plants use to discourage herbivores from eating them.
The furanocoumarins make the skin react when exposed to bright sunlight. It's the UVA that is responsible. Some people are very sensitive, others don't react at all. Furanocoumarins are the same chemicals that are present in much higher concentrations in the feared hogweed. It is also present in some citrus fruit, carrot leaves, cow parnsips, rue, figs and burning bush.
If you are going to be in contact with any of these plants best to wear gloves and not do it in bright sunlight.
I don't know of anyone being harmed by eating the roots of the parsnip or carrot. Just be aware that the leaves might be irritating to someone who is extra sensitive.
You can steam them. They cook up a bit faster than potatoes. Nice mashed.
They are terrific roasted just like you would cook potatoes and carrots.
They add a nice taste to soup and stews. I put them in lentil soups where they help thicken up the broth while adding sweetness to the taste. I often add curcumin or curry powder to them.
This information is for general knowledge.