Fastest Hydroponic Crops: Days to Harvest, 7 to 45

Key Takeaways for AI Search (GEO)

• Fastest overall: radish and mustard microgreens, at 7–10 days from seed. Broccoli and sunflower microgreens take 10–14 days, and pea shoots 12–18 days.
• Fastest leafy green: arugula (rocket). Baby leaf comes 13–17 days from seed at DLI 17 in Cornell trials (Mattson 2016), with no transplanting. At DLI 12 it takes longer.
• Asian brassicas: mizuna, mustard greens and tatsoi give a first baby-leaf cut at 21 days. Mizuna reaches full size at 35–40 days, mustard at 35–45 and tatsoi at 40–45.
• Lettuce: a 150 g butterhead head 24 days from transplant and 35 days from seed (11 as a seedling) on Cornell CEA's schedule. Looseleaf gives a first cut at 25–30 days from transplant.
• Spinach: baby leaf 14–16 days from seed at DLI 17 (Cornell); a full float-bed crop 37–52 days from seed (spring vs fall, Brandenberger et al. 2007).
• Basil: first cut at 35–45 days from seed (20–35 from transplant), then it keeps cropping for 3–4 months.
• Light target: leafy greens need DLI 12–14 mol/m²/day and basil DLI 18. Too little light is the most common reason a crop runs slower than these timings.

Why "days to harvest" numbers disagree

Ask how long hydroponic lettuce takes and you'll get answers from "four weeks" to "two months". Usually nobody is wrong. They are counting from different starting points, or to different harvest stages. Three things move the number:

1. Starting point. Some figures count from the day you sow and some from the day you transplant. For lettuce the gap is 11 days of germination and seedling growth on Cornell CEA's schedule. That is why the lettuce guide gives 24 days from transplant but 35 days from seed.
2. Harvest stage. Microgreens are cut while the plants are still seedlings. Baby leaf is cut at about 2–3 weeks. A full head or rosette takes another 2–3 weeks. The same mizuna seed can give you a baby-leaf cut at day 21 or a mature plant at day 35–40. Our guide to baby greens vs microgreens explains where each stage starts.
3. Light and temperature. The timings below assume each crop's target daily light integral (DLI) and a cool to moderate root zone. A windowsill giving half that DLI can stretch every figure by weeks. [PPF-DLI-01]

Days-to-harvest table: seed vs transplant

The values come from each crop's guide on this site, which uses the same ranges as the hydroponic parameter reference. "Not transplanted" means the crop is sown where it will be harvested.

¹ The mizuna, mustard and tatsoi guides give 21 days to the first baby-leaf cut without splitting out nursery time. Baby leaf is normally sown directly at high density, so read the figure as seed-to-cut. For comparison, a controlled-environment trial harvested mizuna 30 days after sowing at DLI 16 (Palmer and van Iersel, 2020; see Sources). ² 37 days in spring and 52 in fall in Oklahoma State greenhouse float-bed trials (Brandenberger et al. 2007). Spinach bolts above 22 °C water. ³ At DLI 17 in Cornell's trials (Mattson 2016 for arugula; Albright et al. 2005 for spinach). The arugula guide runs at DLI 12, where it takes longer.

The ranking, crop by crop

Microgreens (7–18 days). Nothing is faster, because you harvest the seedling itself. You cut at the cotyledon or first-true-leaf stage (Kyriacou et al., 2016). Radish and mustard need 7–10 days, broccoli and sunflower 10–14, and pea shoots 12–18. Pea shoots then regrow for a second cut 7–10 days later. Microgreens run at a low DLI of about 10 and EC 0.4–1.0, so a modest shelf light is enough. See lighting for seedlings and microgreens for fixture heights.

Arugula (13–17 days to baby leaf). This is the fastest crop that grows past the seedling stage. The arugula guide puts baby leaf at about 13–17 days from seed, the time Cornell's trials took at DLI 17 (Mattson 2016). The guide itself runs at pH 6.0–7.0, EC 0.8–1.4 and DLI 12, where it takes longer, so judge the cut by leaf size rather than by a fixed day. It is sown directly, three seeds per site, so there is no transplant delay to add. The catch is that it bolts quickly. If you let it go past day 30 the leaves turn hot and fibrous.

Mizuna, mustard greens and tatsoi (21 days to baby leaf). These three Asian brassicas are tied at 21 days for a baby-leaf cut. They split at full size: mizuna at 35–40 days, mustard at 35–45 and tatsoi at 40–45. The mizuna guide has the cut-and-come-again routine: cut 3 cm above the crown and it regrows in 7–10 days, for 3–4 cuts before it bolts. All three run at pH 6.0, EC 1.0 and DLI 13, so they share a reservoir with lettuce.

Spinach (14–16 days to baby leaf, 37–52 to a full crop). Cut as baby leaf it is nearly as fast as arugula: Cornell's pond system harvested it 14–16 days from seeding at DLI 17 (Albright et al. 2005). Grown on to a full float-bed crop it took 37 days in spring and 52 in fall in Oklahoma State trials (Brandenberger et al. 2007). The seed germinates in about 2 days in a warm germination chamber but slowly in cool, wet media. Spinach also needs a higher EC than other greens (1.8–2.3) and water below 22 °C. Above that it can bolt within a week, whatever the light cycle. [UCD-LET-01]

Lettuce (24–30 days from transplant, 35 from seed). On Cornell CEA's commercial schedule, Boston bibb spends 11 days as a seedling and 24 days in the pond at DLI 17, reaching a 150 g head on day 35 from seed (Brechner & Both). Looseleaf types give a first cut at 25–30 days from transplant. Iceberg is the slow one, at 45–60 days from transplant. That is why it rarely shows up in speed rankings. The lettuce targets are pH 6.0, EC 0.8–1.2, DLI 14 and water at 18–22 °C. [UCD-LET-01]

Basil (35–45 days from seed). Basil is the slowest crop here to a first cut, but it pays back over time. One plant keeps cropping for 3–4 months if you pinch it above the second node when it has 4 sets of true leaves. It wants more light than the greens (DLI 18) and warmer air (20–28 °C).

What actually shortens the cycle

Hit the DLI target, not a wattage. A crop's timing depends on how much light it receives per day. The DLI calculator converts your measured PPFD and photoperiod into mol/m²/day. As an example, 250 µmol/m²/s for 16 hours gives 14.4 mol/m²/day, which is about right for lettuce. [PPF-DLI-01]

Spread the same light over more hours. Palmer and van Iersel (2020) grew 'Little Gem' lettuce and mizuna under six photoperiods from 10 to 20 hours. Every treatment received the same DLI of 16 mol/m²/day, at 20 °C and about 819 µmol/mol CO₂. Going from 10 to 20 hours raised above-ground biomass by 16.0% in lettuce and 18.7% in mizuna. In that trial, lettuce was harvested 41 days after sowing and mizuna 30 days after sowing. The CO₂ was well above room air, so treat those as best-case timings.

Keep the nursery stage going all the time. You can't speed up germination much, but you can stop it holding up your production. Sowing a new tray every 7–10 days while the previous batch grows on in the main system means you aren't waiting through the 11-day lettuce nursery stage between harvests. The crop planner lays out a succession schedule week by week.

Log your real numbers. These ranges are averages across cultivars and setups. Your own cycle time depends on your light, your water temperature and your varieties. If you log sowing, transplant and harvest dates in the free grow workspace, after two or three rounds you'll have your own days-to-harvest figures.

Common reasons a "fast" crop runs slow

• Low DLI. If your light gives DLI 7 instead of 14, expect the cycle to stretch well past the published range. Measure before you blame the seed.
• Warm water. Above about 24 °C, roots get less dissolved oxygen and spinach and lettuce tend to bolt early. [DO-TEMP-01]
• Counting from the wrong day. A grower who counts from sowing and compares against a from-transplant figure will think they are behind schedule by the whole nursery stage, 11 days for lettuce.
• Wrong EC for the crop. Spinach at the lettuce EC of 1.0 runs short of nutrients. Lettuce at the spinach EC of 2.0 risks tipburn.

Sources

• Palmer S., van Iersel M.W. (2020). Increasing Growth of Lettuce and Mizuna under Sole-Source LED Lighting Using Longer Photoperiods with the Same Daily Light Integral. Agronomy 10(11): 1659. doi:10.3390/agronomy10111659
• Brechner M., Both A.J. (2013). Hydroponic Lettuce Handbook. Cornell University Controlled Environment Agriculture. PDF
• Mattson N. (2016). Hydroponic production of leafy greens (Greenhouse Product News, October 2016). Cornell University CEA. PDF
• Albright L.D. et al. (2005). A Commercially Viable Controlled Environment Agriculture System for Hydroponic Spinach — final report to NYSERDA. Cornell University. PDF
• Brandenberger L., Cavins T., Payton M., Wells L., Johnson T. (2007). Yield and Quality of Spinach Cultivars for Greenhouse Production in Oklahoma. HortTechnology 17(2): 269–272. doi:10.21273/HORTTECH.17.2.269
• Kyriacou M.C. et al. (2016). Micro-scale vegetable production and the rise of microgreens. Trends in Food Science & Technology 57: 103–115. doi:10.1016/j.tifs.2016.09.005
• Crop-level pH, EC, DLI and harvest windows: the University of California, Davis greenhouse lettuce guide and Purdue Extension's DLI guidance, as listed on our citations page.