Turnip

A turnip planted today gives you baby greens in 2 weeks, baby roots in 30 days, and full-size roots in 60. The dual-harvest math is simple: you get the root at $1.75/lb and the greens at market prices ranging from $2-4/lb (USDA AMS Specialty Crop Market News, 2023), and most gardeners throw the greens away. The vegetable most people consider a last resort is actually one of the faster payback crops in the cool-season garden.

What it actually is

Turnip (Brassica rapa subsp. rapa) is an annual biennial grown as an annual. The edible root is a swollen hypocotyl - the stem tissue just below the soil line - rather than a true root. The tops (greens) are the leaves, and they’re edible at any size. Turnip is the same species as napa cabbage and bok choy (B. rapa); the groups just emphasize different parts.

Baby/salad turnips (Hakurei, Tokyo Market) are harvested at golf-ball size, 30-35 days. Thin-skinned, crisp, mild. They don’t need peeling and are good raw - more like a radish in use than a traditional cooked turnip. Hakurei in particular commands $3-5/lb at farmers markets.

Standard turnips (Purple Top White Globe, Seven Top) grow to 3-4 inches across and are harvested at 55-60 days. The skin toughens; these are for cooking. Purple Top White Globe is the standard American turnip - mild, starchy, holds well in storage.

Turnip greens types (Seven Top) are grown primarily for the tops rather than the root. The root is edible but secondary; the greens are the product, harvested repeatedly cut-and-come-again style.

The ROI case

A $1.99 packet contains 400-600 seeds. At 4-inch spacing for baby turnips or 6-inch spacing for full-size, one packet plants a lot of ground. Per-plant seed cost is fractions of a penny.

Baby Hakurei turnips at $4/lb at farmers markets return $3 per square foot in 35 days - faster than almost anything except radishes. Standard turnips at $1.75/lb average and 0.75 lb/plant return less per plant but store for 2-3 months in a cool root cellar or refrigerator, stretching the value across winter.

The greens, if you use them: turnip greens are sold at $2-4/lb fresh (USDA AMS). A 4-inch bunch of thinnings weighs about half a pound. In a 4-foot row you’ll thin 8-12 plants - that’s 4-6 lb of greens across the thinning process alone. Most people compost this. The ones who don’t get their money’s worth much faster.

Growing requirements

Direct seed only. Turnips do not transplant well - the root development is disrupted by transplanting and you get fanged, forked, or stunted roots. Broadcast in rows 6-8 inches apart, cover with 1/4 inch of soil, and thin to 4-6 inches for baby types or 6-8 inches for full-size.

Germination occurs in 3-7 days at soil temperatures of 50-70°F. Turnips tolerate light frost; you can plant 4-6 weeks before last frost in spring or 6-8 weeks before first fall frost. The fall crop in most zones is better: the roots sweeten in cool soil, and you’re harvesting into October or November when few other crops are still producing.

Soil pH 6.0-7.0. Turnips are light feeders - amend with compost before planting, but heavy fertilization pushes leafy top growth at the expense of root development. Keep the soil consistently moist; irregular watering produces pithy, bitter roots.

Planting depth: 1/4 inch maximum. Turnip seeds are small and germinate best with good soil contact and light. Press the seedbed firmly after sowing.

What goes wrong

Flea beetles (Phyllotreta species) leave tiny round shot holes in young leaves and can devastate seedling-stage turnips. Row cover over newly seeded areas prevents adult beetle feeding. Remove once plants are 3-4 inches tall and growing vigorously. Flea beetle pressure typically drops as temperatures cool in fall - fall plantings suffer less than spring.

Root maggots (Delia floralis - turnip root maggot) tunnel through roots, creating brown scarring and entry points for rot. The adult fly resembles a small housefly and lays eggs at the soil line. Row cover through the first 4 weeks of growth prevents egg-laying. Crop rotation - no brassicas in the same bed for 3+ years - reduces soil population.

Downy mildew (Peronospora parasitica) appears as yellow patches on upper leaf surfaces with gray sporulation below. Thin plantings improve air circulation; avoid overhead irrigation in evening. More common in fall crops during wet weather.

Pithy roots result from heat, drought stress, or growing roots too large. Harvest on schedule - roots left in warm soil past peak become spongy inside.

Harvest and storage

Pull baby turnips when the shoulder of the root is 1-2 inches across. At this size they’re crisp and thin-skinned - no peeling required. Pull by the top; the greens and root together are one product at baby stage.

For full-size turnips, harvest when the root is 2.5-3 inches across. Larger is not better - roots over 3 inches get pithy and strongly flavored. After a frost the flavor improves noticeably.

Turnip greens: cut 1 inch above the soil. The plant regrows from the crown 2-3 times before quality declines. For cooking, wash and cook without long blanching - turnip greens need only 5-10 minutes of simmering.

Full-size turnips store in a cool, humid root cellar or refrigerator for 2-3 months. Remove the tops first; tops left on draw moisture out of the root.

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Related crops: Radish, Arugula

Related reading: Succession Planting Calendar - how to stagger fast-maturing crops like turnips and radishes for continuous harvest through spring and fall