An iconic roasted veg on the Christmas dinner table, parsnips are primarily harvested in winter because they taste sweeter once they have experienced a frost. This alone makes them a perfect, low maintenence crop to grow in our climate, giving us something to harvest during the cold days of winter.
When parsnips are exposed to near-freezing temperatures, the stored starches are broken down and converted to sugar, which is why they have that delicious sweetness. This technique is actually the parsnip’s defence mechanism against the cold weather, as the sugar molecules make the water in the plant cells less likely to freeze.
A firm favourite in our winter diet, parsnip, Pastinaca sativa, is a root vegetable closely related to carrot and parsley, belonging to the flowering plant family Apiaceae. They are a slow-growing vegetable which can be left in the soil all winter, meaning you can use the space around them to grow quicker-growing crops like radish or lettuce.
Packed full of vitamin C, potassium, folate, and fibre, parsnips deliver a powerful hit of antioxidants so it is really worth considering growing them next year.
Parsnips are grown from seed. To guarantee germination, always use a fresh pack of seeds since parsnips lose their viability rapidly after about a year. Seeds can be soaked overnight to hasten germination.
Parsnips prefer a sunny area of the garden with fertile, deep, well-draining soil. Like carrots, they do not like a rich soil so there is no need to add manure.
Plant parsnip seeds in the spring in a fine tilth, in widely-spaced rows, when the soil temperature is 13-18C (55-65F) although if you can wait until the soil is warmer in April, you will see better results.
Keep the seedbed evenly moist and be patient, parsnips can take up to 28 days to germinate.
When the seedlings are about 15cm (6in) in height, thin them to 8cm (3in) apart. Parsnips can be enjoyed as mini veg before they are fully grown and this is a great way to thin rows out without wasting any plants.
High summer temperatures can reduce growth, decrease quality, and cause bitter roots. To protect the plants from higher temperature, apply organic mulches such as grass clippings, leaves, straw, or newspapers. A mulch will cool the soil and reduce water stress, resulting in happier and tastier parsnips.
Shorter-rooted parsnips can be grown in deep containers, or even an old dustbin with plenty of drainage holes drilled. They need plenty of room for the roots to grow straight down, so the key to container growing is to make sure your planter is deep enough.
Overwintering parsnips requires a heavy mulch on top of them, which means they will store beautifully in the ground until you are ready to use them. If your garden or allotment has heavy, clay soil, it can be better to dig up the roots in late autumn to store in the shed in wooden boxes, layered amongst compost or sharp sand. Parsnips can be kept in the refrigerator for up to four weeks.
For overwintered parsnips, remove the mulch from the beds in spring, and harvest the roots before the tops begin to sprout – never let the plants flower before harvesting.
Parsnips sown between March and May will be fully grown from late October or November, when the leaves start to die back. For the best flavour, parsnips should be harvested when they are a medium width in size, as larger roots tend to be woody and fibrous.
With a winter-cropping veg that tastes great roasted or added to soups, and is full of nutrition, you can keep harvesting parsnips over Christmas and well into the New Year.