Since earwigs can clear a newly sprouted row in a couple of nights, my partner and I dust seedlings with rotenone powder to help them along their slow and steady way. Thankfully, parsnips are not bothered by any other insects later on.
“Sow thick, thin quick.” This old rule for radishes applies equally to parsnips. Once up and growing, about the time their leaves reach six or eight centimetres high, parsnips need to be thinned to their final spacing, roughly eight centimetres apart—if crowded, you’ll be left with shoestrings. A weekly soaking maintains continual growth and keeps the roots tender; weed as needed.
Harvest your garden-grown parsnips
In our snow-covered, Zone 4 garden, the earth seldom freezes to any depth and parsnips are an early springtime treat, dug the day after the white blanket melts away, and for the next several weeks. And dug they must be: you might pull carrots by hand, but even in sandy soil a parsnip root will have to be loosened carefully and lifted out with a spade.
Parsnips are biennial: roots the first year, flowers and seeds the second. Fresh foliage begins to grow during spring’s first warm days, but the plump, white roots are at their best before new green leaves are very far along—a window of three weeks to a month, well before there is anything else to eat from the garden (except perhaps for Jerusalem artichoke tubers and dandelion greens).
In places where the soil routinely freezes solid, early November is the time to rake a mound of fall leaves, 20 to 30 centimetres deep, over the parsnip row to keep out the hardest frost. This simple protection enables you to sample some roots in December—nice chunks to roast with the festive bird. Those that remain will be sweet and ready first thing in spring.
Wild ancestors of today’s parsnips are thought to have originated in the Mediterranean region and spread throughout Europe, which is where modern parsnips were developed during the Middle Ages. Little has been done to them since then. Most catalogues list only a few cultivars: ‘Harris Model’, said to be “free of side roots,” and ‘Hollow Crown’ are two that are widely available. ‘Andover’ and the hybrid ‘Gladiator’ both have stronger tops (which is of more interest to commercial growers who harvest mechanically), and a slightly higher sugar content, but any parsnip exposed to cold will turn sweet. All varieties are hardy across the land, even where the ground freezes deep and long, and all grow roots from 15 to 30 centimetres long.