The parsnip is considered a winter vegetable for two reasons. Firstly, it’s often used as a component in soup packs; secondly, the taste greatly improves when subjected to frosty conditions. Cold causes the starches to convert to sugars. On the Highveld, parsnips can be grown in summer for marketing during winter and can stay in the soil for quite some time while you harvest them as required. The greatest challenge with parsnips is germination: the seed rapidly loses viability after the first season.
It should therefore always be fresh. Make sure of this when you buy seed or you will waste valuable time and effort. Many farmers select the best roots and transplant them in an out-of-the-way area to obtain their own seed for the following crop. This is a wise way to ensure good germination potential.
Using fresh seed solves only part of the germination problem. Another difficulty is that the seed can take up to a month to germinate in some conditions. It helps to soak the seed in warm water for a day before planting. Dry it just enough on paper in the shade so that it is easy to handle for planting.
Sow the seeds 1cm deep in rows 45cm to 60cm apart, with an in-row spacing of between 3cm and 5cm. Thin out to stand eight to 10cm apart once established. Because the seeds are just 1cm deep and take two or more weeks to germinate, irrigation has to be managed carefully.
If you want to grow the crop on a larger scale, buy a small tropical fish tank with an aerator and thermostatically controlled heater. Fill it with water and set the temperature at 15°C to 18°C. Place some seed in a muslin bag and suspend in the water for two days; then add the rest of the seed to the tank and wait.
When the seed in the bag starts to germinate, remove the rest of the seed from the tank by pouring them through a strainer and letting them part-dry on paper in the shade. If you plant into moist soil, only a very light irrigation is required before emergence. (The seed in the muslin bag simply provides a warning that germination is close.)
Another method, also involving the fish tank, is to mix some gel powder in water according to instructions. When it’s ready, the gel will hold the seeds in suspension. With this method, wait until the roots are just emerging from the seeds and then mix into the gel. Place in a strong plastic bag after attaching a tube into the corner so you can squeeze the seed into the planting furrow.
Tie a rod to the tube so that you can better control the positioning of the seed and tie the open section of the bag so that you can create pressure to push the seed-loaded gel through the tube.
Parsnips require reasonably fertile soil. Avoid fresh manure, however. Keep the leaf colour right with LAN side dressings when necessary. Before the seedlings emerge, apply linuron as a herbicide. With a pre-germination method, apply the linuron just after planting. If you plant ungerminated seed, wait until just before the parsnips germinate, when most of the weeds have already emerged. When the crop is on its way, irrigate deeply less often as this crop has a deep root system.
If you’re marketing in summer, and have the facilities to do so, keep the harvested roots in a cool room for a few weeks before marketing in order to convert the starches to sugar and present a tastier product. Wash first, then put the roots in their packaging before placing in a cool room, if this is more convenient.