Corn growth stages V1–R6 with a scouting checklist
Stage corn with the leaf-collar method, what to scout at each V and R stage, rough GDD timing, herbicide and fungicide label cut-offs, and black layer.
- Where:
- US Corn Belt, Ontario
- When:
- May–September
- Updated:
- October 19, 2026
- Reading time:
- 7 min
Short answer
Stage corn by counting leaves with a visible collar, the light band where the blade meets the sheath, starting with the short, round-tipped first leaf; a plant with six collars is V6, whatever is still rolled in the whorl. Vegetative stages run from VE through VT (last tassel branch visible), reproductive stages from R1 (silk) to R6 (black layer), and a field is at a stage once half the plants have reached it. From emergence, expect a new collar about every 82 growing degree days (GDD) to V10 and every 50 GDD after that, and 55 to 65 days from silking to black layer. Most postemergence herbicide labels cut off between V5 and V8 or 8 and 30 inches (20–76 cm), whichever comes first; the corn fungicide window is VT–R2.
How to stage a corn plant
Leaf-collar method. Count every leaf with a visible collar, beginning with the lowermost short, rounded-tip leaf; leaves still rolled in the whorl do not count. Vegetative staging ends at VT, when the lowest branch of the tassel is visible, and reproductive staging begins at R1 when any silk is visible outside the husk. Stage a field on the basis of at least 50 percent of plants.
When lower leaves are gone. Once corn is knee-high the lowest leaves tear off or rot away, and a plant at V12 may show only eight collared leaves. Dig a plant without breaking the stalk, split it lengthwise through the root ball, and find the lowest clearly elongated internode above the woody triangular base; it is only 1/2 to 3/4 inch (1.3–2 cm) long. The leaf at the node directly above it is usually leaf 5; count collared leaves upward from there, so seven above leaf 5 makes the plant V12.
The "droopy leaf" method. Hail adjusters count to the uppermost leaf that is at least 40 to 50 percent out of the whorl, which gives a number one higher than the collar method up to V5–V6 and two higher once corn is 18 to 24 inches (45–60 cm) tall. Older herbicide labels skipped the short first leaf and counted to the uppermost leaf half out of the whorl, which roughly matches the collar count; newer labels cite the collar method but are not always clear about the first leaf. If a cut-off is close, ask the registrant which count the label means.
Stage-by-stage table
GDD figures are cumulative from planting for a 105–110 day hybrid in the central Corn Belt (86/50 °F method); treat them as a rough calendar.
| Stage | How to recognise it | What to scout or do | Label cut-offs and timing notes |
|---|---|---|---|
| VE (≈100–120 GDD) | Coleoptile through the soil; 5 days in warm soil, 3 weeks or more in a cold spring | Stand counts, emergence uniformity, seedling pests, crusting | Pre-emergence residuals must be on before this |
| V1–V2 | First leaf short with a round tip; second and later leaves pointed | Cutworm, wireworm, seed-corn maggot; purple or yellow seedlings (usually cold) | — |
| V3–V5 (V3 ≈325 GDD) | About 8 inches (20 cm) tall at V3; growing point still below ground, so frost and hail rarely kill the plant, but flooding can | Nodal roots take over from seminal roots around V3; weed escapes; herbicide injury | Dicamba (higher rate) 8 in or V5; atrazine 12 in (30 cm); 2,4-D broadcast under 8 in (20 cm) |
| V6 (≈550 GDD) | Growing point and tassel initial move above the soil surface; nodal roots from the 3–4 lowest nodes | Sidedress N window V6–V8; first rootworm lodging and corn borer leaf feeding; ear shoot initiated V5–V6 and kernel row number set V5–V7 | Glufosinate V6 (drop nozzles to 36 in); nicosulfuron 20 in or V6 (drop nozzles to 36 in or V10) |
| V7–V9 (V9 ≈730 GDD) | Rapid height growth; a split stalk shows ear shoots at most above-ground nodes, of which only the top one or two will make a harvestable ear | Kernels per row being set; foliar nutrient symptoms; lower-canopy disease in corn-on-corn | Glyphosate, mesotrione, topramezone and tembotrione 30 in or V8 (glyphosate drop nozzles to 48 in); check each label |
| V10–V12 (V12 ≈910 GDD) | New leaf every 2–3 days; rapid nutrient and dry-matter uptake begins about V10 | Kernels per row set between V12 and V15, so water and N stress now costs ear size; start tar spot and gray leaf spot scouting in the lower canopy | Most broadcast herbicide labels have expired; dicamba (low rate) 36 in or 15 days before tassel |
| V13–V18 (V15 ≈1,045, V18 ≈1,180 GDD) | New leaf every 1–2 days; brace roots from above-ground nodes; silks growing inside husks | Drought-sensitive window opens two weeks before silking; ear size is final 10–14 days before silk; scout the ear-leaf zone weekly | Fungicide window has not opened yet |
| VT (≈1,260 GDD) | Last tassel branch visible; plant at full height; pollen shed 1 week per plant, 1–2 weeks per field | Peak hail and leaf-loss sensitivity VT–R1; rootworm beetle silk clipping; fungicide decision from disease in the lower canopy | Corn fungicide window opens (VT–R2) |
| R1 silk | Silks outside the husk; pollen captured and ovules fertilised | Silk clipping, pollination check (shake test), drought and heat stress | Fungicide window still open; see the VT–R2 timing guide |
| R2 blister (10–12 days after silk) | Kernels white blisters with clear fluid, about 85 percent moisture | Kernel abortion under severe stress; disease moving above the ear leaf | Fungicide window closing; check the grain, forage and silage PHI |
| R3 milk (18–20 days) | Kernels yellow outside, milky inside, about 80 percent moisture | Stalk health, early ear rots; late tar spot or southern rust | Late fungicide rarely pays; see the timing guide |
| R4 dough (24–26 days) | Doughy kernel, about 70 percent moisture, kernels at about one third of final dry weight; cob turning pink or red | Ear rots, stalk rots, lodging risk; push test | — |
| R5 dent (31–33 days) | Dent at crown, milk line moving down, about 60 percent moisture at onset; about 30 days to maturity | A killing frost at full dent costs about 40 percent of yield, at half milk line about 12 percent | Schedule harvest order by stalk strength |
| R6 black layer (55–65 days after silk) | Milk line gone; black abscission layer at kernel tip 2–3 days after maximum dry weight; kernel moisture averages 30 percent (25–40) | Stalk integrity, ear drop, dry-down; stress after R6 affects yield only through lodging and ear loss | Preharvest intervals count back from harvest, not from R6 |
Herbicide cut-offs above are examples from US labels compiled by the University of Minnesota in June 2025, listed as "whichever comes first"; the same active ingredient can carry a different cut-off in a different product, and in a tank mix the most restrictive label governs. Canadian labels can differ, so Ontario growers should read the PMRA-registered label and the provincial guide rather than a US table.
Rough GDD timing
Emergence needs about 100–120 GDD from planting. From emergence, each new collar takes about 82 GDD through V10, then about 50 GDD per leaf to the final leaf. Severe stress slows stem and sheath elongation and delays collars beyond what the model predicts, so use GDD to plan scouting trips and spray windows, not to settle a label question; for that, count collars in the field.
Black layer
Physiological maturity (R6) arrives 55 to 65 days after silking, when the milk line disappears and kernel dry weight is at its maximum. The black layer forms at the kernel tip two to three days later and confirms that nothing more is moving into the grain. Kernel moisture at black layer averages about 30 percent but ranges from 25 to 40 percent, so black layer means the yield is made, not that the crop is ready to combine. From R6 the only yield left to lose is through lodging, ear drop and ear rots, which is where the push test and harvest order come in.
Why staging matters for labels and timing
Herbicide labels state a maximum stage or height because a spray past that point risks crop injury and residue violations, and sidedress timing, insect thresholds and the fungicide window all reference V and R stages. Potential ear size is set between about V5 and V15, so stress in that window shows up as short ears, while stress around silking shows up as missing kernels. Count collars at every scouting stop and record the stage with the date.
Sources
- Corn growth stages — Iowa State University Extension encyclopedia
- Determining corn leaf stages — Purdue Agronomy (Nielsen)
- Predict leaf stage development in corn using thermal time — Purdue Agronomy (Nielsen)
- Ear size determination in corn — Purdue Pest & Crop, June 2023
- Grain fill stages in corn — Purdue Agronomy (Nielsen)
- Vegetative corn growth stages and scouting tips — Pioneer agronomy
- Updated corn growth stage cutoffs for postemergence herbicide application — University of Minnesota Crop News, June 2025
Label first. Always read and follow label directions before buying or using a pesticide, and follow all federal, state or provincial and local regulations — the label is the law. In the US, use products registered by EPA and approved in your state; in Canada, use only products registered by Health Canada's PMRA (PCP number) and check the current label in the PMRA label search. Products, rates and restrictions differ between countries and between states and provinces.
This guide is educational and does not replace a site-specific recommendation from your agronomist or Certified Crop Adviser. Reference to a product is not an endorsement over similar products; users assume responsibility for use in accordance with current label directions. Last updated October 19, 2026.