Cotton, Soybean and Oilseed Growing Guides

The growth stages of cotton

Cotton is a perennial shrub grown as an annual, and it keeps adding branches, squares and bolls for weeks at a time. Its stages overlap more than those of grain crops, so growers track it by both the calendar and the plant itself. The timings below are typical for a warm season and vary with temperature, variety and planting date.

Our article on the temperature and rainfall cotton needs covers the conditions at each stage, and cotton production challenges covers the common problems.

Sowing conditions for cotton and soybeans

Most stand problems start at planting. Cotton is a warm-season crop, and a common guideline is to plant once soil at seeding depth stays at or above about 65°F (18°C) for several days with a warm forecast ahead. Cold, wet soil slows emergence and invites seedling disease. Soybeans tolerate cooler soil and are often planted from about 50°F (10°C), and early planting usually helps yield where frost risk allows. Canola and peas are cool-season crops and go in early in spring, or in fall where winters are mild. For all of them, aim for even seeding depth and good seed-to-soil contact, because an uneven stand costs yield all season and makes later decisions harder.

Heat units and cutout

Because cotton development follows temperature more closely than the calendar, many growers track heat units, often called DD60s: degree-days above a base of 60°F (about 15.6°C). A cool spring stretches every stage, and a hot one compresses them.

The other number to know is nodes above white flower (NAWF). Count the main-stem nodes between the uppermost first-position white flower and the top of the plant. When that count falls to about five, the plant has reached “cutout”: it’s putting its energy into the bolls it already has rather than new fruit. Cutout timing guides the last irrigation and insect decisions and, later, defoliation. Insects matter all season. Our guide to cotton jassid control covers one of the main sucking pests.

Soybean growth stages

Soybeans use a simple two-part system. Vegetative stages run from VE (emergence) and VC (unrolled unifoliate leaves) through V1, V2 and so on, counted by fully developed trifoliate leaves. Reproductive stages run from R1 (beginning bloom) to R8 (full maturity), with R3 (beginning pod), R5 (beginning seed) and R6 (full seed) the ones that matter most for yield. Stress during pod and seed fill, from R3 to R6, costs the most yield. For yield figures by state, see our page on average soybean yield per acre.

Canola and other oilseeds

Canola is a type of rapeseed bred in Canada to be low in erucic acid and glucosinolates, which made its oil suitable for food and its meal suitable for animal feed. It grows through emergence, rosette, bolting, flowering and pod-filling stages, and flowering is the stage most sensitive to heat. Canola is one of Canada’s most valuable crops and exports, as our article on canola exports describes. Sunflower, peanut (groundnut) and sesame are the other major oilseeds, and each has its own stage system and pest problems. Peanuts, for example, set their pods underground after a stalk called a peg grows down into the soil, so crusting and calcium supply in the pod zone matter more than for most crops.

Pulses and nitrogen

Pulses (dry beans, peas, lentils, chickpeas) and soybeans are legumes. Rhizobium bacteria in nodules on their roots fix nitrogen from the air, so a well-nodulated crop needs little or no nitrogen fertilizer, and it often leaves some for the next crop. On fields where the crop hasn’t been grown recently, seed is treated with the right inoculant for that crop. Pink or red insides on nodules a few weeks after emergence show that fixation is working. Adding nitrogen fertilizer to a well-nodulated legume mostly replaces what the bacteria would have supplied, so it rarely pays. Our bean seed germination guide covers the first week.

Tracking oilseed and pulse crops from satellite

Satellite images follow these crops well, because their canopies change a lot through the season. Vegetation indices rise as the canopy closes, plateau through flowering and fall as leaves age or are defoliated, so an unusual dip mid-season is worth a field check. Cotton is among the top crops by area on our platform. Our satellite crop monitoring gives crop health, water need, pest and disease risk and a yield estimate for each field.