Root vegetables span more range in days-to-harvest than almost any other category in the garden. Radish is ready in 25 days. Parsnip takes 120 and still isn’t done until frost hits. That range creates meaningfully different ROI math - and most comparisons ignore it entirely by treating every root crop the same way.
They aren’t the same problem. A crop you can turn over four times in a season computes differently than a crop that ties up ground from May to November. The speed advantage is worth calculating. So is the soil dependency that makes carrot ROI wildly variable between a gardener with a raised bed and one working clay subsoil.
This article compares five root crops - radish, carrot, beet, turnip, and parsnip - on annualized per-square-foot value, using retail prices from USDA AMS Specialty Crop Market News and yield data from Purdue Extension and University of Minnesota Extension vegetable production guides.
The Spectrum
At one end: radish (Raphanus sativus), 25 to 35 days to harvest, essentially a sprinter. At the other: parsnip (Pastinaca sativa), 100 to 120 days, and it benefits from being left in the ground through hard frosts. Between them sit carrot (Daucus carota var. sativus) at 70 to 80 days, beet (Beta vulgaris) at 50 to 70 days, and turnip (Brassica rapa var. rapa) at 45 to 60 days.
Each point on that spectrum has a different relationship between planting date, space commitment, and return. Days-to-harvest is not the only variable - yield per planting, number of successions per season, and retail price all feed into the annualized number. The table at the end of this section shows the complete picture, but the per-crop detail matters because the inputs behind the numbers are not all equal.
Radish
Radish is the fastest edible crop in the vegetable garden. ‘Cherry Belle’ hits harvest in 25 days under good conditions. ‘French Breakfast’ runs 28 to 30 days. Even slower varieties like Daikon top out around 50 to 60 days, which still makes them faster than any other root crop in this comparison.
Single-planting yield is 0.5 to 1 lb per square foot, which is not impressive by itself. Retail price is $1.50 to $3.00 per pound for loose radishes or $2 to $4 per bunch at farmers markets (USDA AMS Specialty Crop Market News). At midpoints - 0.75 lb/sq ft and $2/lb - one planting grosses $1.50 per square foot.
That number changes when you account for succession. In zones 5 and 6, you have two cool windows for radish: a spring window from roughly 4 to 6 weeks before last frost through early June, and a fall window from late August through October. Within each window, you can plant every 3 weeks. Four successions per season is a realistic target. Six is achievable in a warm spring followed by a long fall.
Four successions at 0.75 lb/sq ft = 3 lb/sq ft/season. At $2/lb, that’s $6.00 per square foot annualized. Seed cost for four plantings from a single packet runs $3 to $4 total (one $2.49 packet covers more than 100 row feet - you will plant the same packet all season). Net per square foot approaches $5.75 on four successions.
For Daikon specifically: the 50 to 60 day maturity means you get fewer successions, but yield per planting climbs to 1.5 to 2 lb/sq ft in well-prepared soil. Daikon also sells for $1.50 to $2.50/lb at Asian grocery markets and farmers markets. The math works out similarly to standard radish on an annualized basis, with more flexibility in timing.
Carrot
Carrot is the root crop with the highest soil quality dependency in this group. That sentence is doing real work. A gardener with 12 inches of loose, amended growing mix in a raised bed can expect 1.5 to 2 lb/sq ft. A gardener working compacted clay or rocky in-ground soil can expect 0.5 to 0.75 lb/sq ft of stunted, forked roots. No other root crop in this comparison has that variance range. The soil is not incidental - it is the primary determinant of carrot yield.
Assuming good soil: 70 to 80 days to harvest, 1.5 lb/sq ft midpoint yield. Retail price is $1.50 to $2.50/lb conventional, $2 to $4/lb organic (USDA AMS). At $2/lb, that’s $3.00/sq ft per planting. In zones 5 to 6, you can fit two plantings - one spring and one late summer for fall harvest - giving an annualized gross of $3 to $6/sq ft depending on whether you get one or two full crops out.
Thinning is mandatory. Unthinned carrot beds produce spindly, forked, unmarketable roots regardless of soil quality. Space to 2 to 3 inches in rows or broadcast seeding. Most gardeners skip this step and then blame the seed.
Seed cost is $2.49 to $3.49 per packet, and carrot seed is tiny - one packet plants a 50-foot row. Cost per square foot of bed is minimal, under $0.10 for most plantings.
Carrots store well. In zones 6 and warmer, you can leave them in the ground under mulch through early winter and harvest as needed. Refrigerator storage holds 4 to 6 weeks. This makes the fall planting particularly useful - you are not racing to process a harvest all at once.
Beet
Beet produces two distinct sellable products from one planting, which changes the effective yield calculation compared to a single-product crop.
At 3 to 4 inches tall, beet thinnings are edible greens worth $3 to $5 per pound at farmers markets. Most gardeners throw them away. If you treat them as a crop - harvest thinnings deliberately into a bowl rather than pulling and discarding - you are adding $1 to $2 worth of greens per square foot before the root even approaches maturity. The root itself matures in 50 to 70 days at 1.5 to 2.5 lb/sq ft and retails for $1.50 to $2.50/lb (USDA AMS).
Take the midpoints: 2 lb/sq ft at $2/lb = $4.00/sq ft from the root. Add $1.50 worth of greens (conservative). That’s $5.50/sq ft from one planting of beet. You can succession plant twice in most zones - one spring planting and one late summer planting for fall harvest. Annualized gross: $8 to $11 per square foot when you count both products.
Three varieties worth knowing: ‘Detroit Dark Red’ (60 days, reliable and widely adapted), Chioggia (55 days, Italian heirloom with red-and-white candy-stripe interior, milder flavor), and Golden (55 days, yellow, significantly milder and less prone to bleeding when cut). All three perform similarly in yield terms.
Turnip
Turnip is the fastest brassica in the ground and one of the most underused gap-filler crops. At 45 to 60 days to mature roots, it moves faster than any other crop in this comparison except radish. If you have a bed that went empty after garlic harvest in July, a turnip succession goes in immediately and produces before frost.
Like beet, turnip yields two products. The greens are harvested before the root matures and sell for $2 to $4/lb at farmers markets. The root itself retails for $1 to $2/lb, putting it at the lower end of this comparison on root price. But the greens offset that gap.
Turnip tolerates frost. Not just tolerates - it benefits from it. Frost concentrates sugars, and a fall-grown turnip pulled after the first hard frost is noticeably sweeter than a July turnip. If you are growing turnips for table quality rather than just ROI, plan your succession so the roots mature in October or November.
Two plantings per season is straightforward in zones 5 and 6: one spring planting and one late summer planting timed for fall root harvest. Yield at 1.5 to 2.5 lb/sq ft is competitive with beet, and the faster maturity means more flexibility in succession scheduling.
Parsnip
Parsnip is the outlier. At 100 to 120 days to harvest, it ties up a bed from direct seeding in early spring through late fall. You get one planting per season, yield is 1 to 1.5 lb/sq ft, and retail price is $2 to $4/lb - reflecting both the lower production volume and the fact that many grocery stores don’t stock parsnips at all (USDA AMS).
The case for growing parsnips is not ROI-first. The case is availability. If you live somewhere that parsnips aren’t reliably at your grocery store, home-grown is the only practical option. The retail price of $2 to $4/lb means the value is there when you can get the yield.
The germination complication is real and underappreciated. Parsnip seed viability drops dramatically after one year - buy fresh seed every season, not from a packet left over from two years ago. Germination takes 2 to 3 weeks even with fresh seed and favorable conditions. Direct sow as early as the soil can be worked in spring. The long germination window is one reason parsnips feel harder than they are: you sow, nothing happens for three weeks, and most gardeners assume failure before the seedlings have had a chance.
The frost-sweetening phenomenon is documented and significant. Parsnip starches convert to sugars during cold exposure. A parsnip harvested before the first autumn frost tastes starchy and bland compared to one left in the ground until October or November. Do not dig parsnips early. Leave them through multiple frosts. The flavor reward is real and is the main reason parsnip commands a higher retail price than carrot or turnip in specialty markets.
The Comparison Table
This table calculates annualized gross value per square foot - the key number for comparing crops that occupy space for different lengths of time.
| Crop | Days to Harvest | Yield lb/sq ft | Retail $/lb | Seed Cost/Packet | Gross $/sq ft per Planting | Successions/Season | Annualized Gross $/sq ft |
|---|---|---|---|---|---|---|---|
| Radish | 30 | 0.75 | $2.00 | $2.49 | $1.50 | 4 | $6.00 |
| Turnip | 55 | 2.0 | $1.50 | $2.49 | $3.00 | 2 | $6.00 |
| Beet | 60 | 2.0 | $2.00 | $2.99 | $4.00 | 2 | $8.00 |
| Carrot | 75 | 1.5 | $2.00 | $2.99 | $3.00 | 1-2 | $3.00-6.00 |
| Parsnip | 110 | 1.25 | $3.00 | $2.99 | $3.75 | 1 | $3.75 |
Notes: Beet annualized gross does not include greens value; with greens, add $1.50 to $3.00 per planting. Carrot range reflects soil quality variance - the lower end assumes in-ground clay soil, the upper end assumes raised bed with amended growing mix. Radish seed cost assumes one packet covers all four successions.
Parsnip’s $3.75 annualized gross doesn’t look bad in isolation, but against a beet at $8 or a radish at $6, the opportunity cost of that bed space through the entire season is clear. Parsnip earns its place if the retail option isn’t there. If you have access to parsnips at a grocery store, the ROI math doesn’t make a strong case for growing them over higher-turnover crops.
Succession Math: The Radish Case
A 4x4 bed - 16 square feet - planted to radishes with four successive sowings spaced 3 weeks apart:
- First sowing: planted 4 weeks before last frost, harvested 30 days later (before the frost date)
- Second sowing: 3 weeks after first, harvested 30 days later
- Third sowing: mid-August as temperatures drop from summer peak
- Fourth sowing: 3 weeks after third, harvested in October
Each sowing: 16 sq ft × 0.75 lb/sq ft = 12 lb of radishes.
Four sowings: 48 lb total. At $2/lb retail, that’s $96 gross value from a 16-square-foot bed in one season.
Seed cost for all four sowings: $3 to $4. One packet covers the entire season with seed left over. Net: approximately $92 to $93 from 16 square feet.
For comparison, a 16-square-foot bed planted to parsnips produces: 16 sq ft × 1.25 lb/sq ft = 20 lb at $3/lb = $60 gross. Higher per-pound price, much lower annualized return because the bed sat with one crop for seven months.
The radish wins on annualized per-square-foot value despite being the lowest-priced crop in this comparison. Speed is the variable that does it. You are not comparing 0.75 lb at $2/lb to 1.25 lb at $3/lb. You are comparing 3 lb at $2/lb to 1.25 lb at $3/lb.
Soil Preparation
All five root crops prefer deep, loose, rock-free soil. The consequences of bad soil vary by crop.
Radish and turnip are the most forgiving - their roots are short enough that moderately compacted soil produces acceptable results, though you won’t hit yield ceilings. Beet is intermediate. Carrot and parsnip need deep loose soil to produce full-length, straight roots. Rocky soil or clay subsoil without amendment produces forked, stunted carrots and parsnips regardless of seed quality, fertilization, or watering.
A raised bed with 12 inches of amended growing mix is the practical solution for carrot and parsnip yield reliability (see raised bed break-even analysis for the cost math on building versus buying growing mix). In heavy clay soil without a raised bed, treat carrot yield as 0.5 to 0.75 lb/sq ft in your planning rather than the 1.5 to 2 lb/sq ft that good soil delivers. The difference in those numbers changes whether carrots make financial sense for your specific site.
What to Grow
If your goal is maximum annualized value per square foot and you have a full season to plan: beet outperforms the other four on annualized ROI when you count both products, and it does so without the soil dependency that limits carrot performance or the timing constraint that parsnip requires.
If your goal is fastest return on seed investment - useful for new gardeners trying to see results quickly, or for testing a new bed - radish. Nothing else in the vegetable garden pays back in under 30 days.
If you have deep, loose, well-amended soil and want to maximize that asset: carrots. The yield ceiling only becomes accessible in good soil conditions, but 2 lb/sq ft at $2/lb beats most annuals when you achieve it.
If you’re working with a gap in the season after spring crops come out: turnip. Forty-five to sixty days means it fits in windows that most crops can’t use. Plant it after garlic comes out in July and it’s ready in September.
Parsnip: grow it if you can’t buy it locally, or if you want to serve something in December that has no grocery store equivalent at your location. The flavor after frost is genuinely distinct. The ROI math supports it when retail access is the alternative.
Sources: USDA AMS Specialty Crop Market News (retail price data); Purdue Extension Vegetable Production Guides (yield per square foot, spacing requirements); University of Minnesota Extension Root Vegetable Guides (days to maturity, storage, frost tolerance).
Beyond the five crops compared here, several specialty root vegetables command higher retail prices and can outperform conventional roots on ROI math. Celeriac (celery root) retails for $3-5/lb and is rarely well-represented in grocery stores outside urban specialty markets. Salsify and scorzonera - oyster-flavored roots popular in European cooking - are nearly impossible to buy at retail and command $4-8/lb where they’re offered at farmers markets. Horseradish is a perennial root that sells for $4-8/lb fresh and once established requires almost no annual maintenance. Kohlrabi and rutabaga are faster-maturing brassica roots that fill the same seasonal slot as turnip with different flavor profiles worth exploring if you have bed space. Mashua and oca are Andean tubers gaining interest among specialty growers - they’re rarely available at retail and offer good opportunity for farmers market and community supported agriculture (CSA) sales.
Related crop pages: Carrot - Beet - Radish - Turnip - Parsnip
Related articles: Vegetable Value Per Square Foot - Raised Bed Break-Even