Roots are mainly long-term crops, best suited to larger plots where you can plant a worthwhile number and can leave them to grow undisturbed. Reliable, they offer a welcome feast when few fresh crops are available.
How to Grow
This group of vegetables needs an open, sunny site with deep, light soil, free from large stones. They will crop in heavy soil as long as it drains well; on shallow soils, choose varieties with shorter roots. Sow seed in spring, under cover for celeriac, directly outside in drills for the others, planting out or thinning to their preferred final spacings. Keep plants well weeded to reduce competition, and water as required; avoid allowing the crops to become dry because the developing roots may then split when watered.
On smaller plots, interplant slower-growing parsnips and rutabagas with
quicker crops, like radishes and bok choy, sown directly to make better
use of the space. In milder areas, leave the roots in the ground in fall
and winter until needed. In colder, wetter areas, lift and store them.
Types of Root and Step Crops
- Turnips: Turnips are quick growing and can be harvested as baby roots after six to seven weeks or left 11 weeks to grow larger. They prefer cool, moist conditions and need a fertile soil, improved with well-rotted organic matter. For an early crop, sow seed under cover in spring in modules and plant outside when the seedlings have one or two leaves. Instead of thinning, they can also be grown as clusters. Varieties to try: ‘Armand’, ‘Atlantic’, ‘Golden Ball’, ‘Manchester Market’, ‘Purple Top Milan’, ‘Primera’ and ‘Snowball’.
- Rutabagas: Rutabagas are a slow-growing crop, ready to harvest in winter after 20–26 weeks. They need a sunny site with light soil that drains freely but doesn’t dry out. Sow outside in early spring, as soon as the soil is warm enough, directly in drills 3/4-inch deep. Thin seedlings to 9 inches apart, and water and weed regularly. Harvest the roots when 4–6 inches across, and protect roots left in the soil in winter with a layer of straw. Varieties to try: ‘Brora’, ‘Helenor’, ‘Magres’, ‘Marian’ and ‘Virtue’.
- Parsnips: Parsnips need an open, sunny site with light soil that has been deeply dug to allow the roots to grow long and straight. Sow seeds direct in mid- to late spring once the soil starts to warm; germination can be erratic. Thin seedlings to 4–8 inches apart, depending whether you want smaller or larger roots. Water sparingly to encourage deep-rooting, and harvest in late summer. Varieties to try: ‘Avonresister’, ‘Countless’, ‘Gladiator’, ‘Panache’, ‘Pinnacle’, ‘The Student’ and ‘White Gem’.
- Celeriac: Although celeriac is commonly thought of as a root crop, it is the swollen stems that are eaten. It grows in sun or shade but prefers moist, rich soil improved with organic matter. Sow seed in spring in modules at 50 degrees F; grow under cover, harden off, and plant out in late spring or early summer, 12 inches apart with the crowns showing above the surface. Water regularly in summer, and harvest from early fall to late winter. Varieties to try: ‘Brilliant’, ‘Giant Prague’, ‘Monarch’ and ‘Prinz’.
Watch Out for These Pests and Diseases
Rutabagas and turnips are brassicas and suffer similar pests and
Carrot fly maggots affect parsnip and celeriac, burrowing tunnels in the
roots. Stored roots may rot. Protect plants in summer with fine mesh,
24 inches high.
Parsnip canker is a fungal disease that causes brown or black growths on
the roots, which may then rot. Destroy infected plants, grow resistant
varieties, and rotate crops.