University of Arizona a dot Cooperative Extension

Plant Population Evaluation/Management for Cotton
(Publication az1203)
(PDF file version, 28KB)

by Jeffrey C. Silvertooth,
Extension Agronomist - Cotton

One of the most critical, and often most difficult, steps for the production of any crop is that of stand establishment. When considering a given stand and its condition, directly evaluating plant populations in the field can be very helpful. Cotton fortunately, has a strong capacity to adjust to a broad range in plant populations, with general ranges of 20,000 to 70,000 plants per acre (ppa), and optimal ranges described as about 25,000 to 50,000 ppa. These ranges in final plant population apply to both Upland and Pima in Arizona, and for row spacings of 30 to 40 inches. Unique field conditions or specific varieties may require higher or lower plant populations, which are often best determined by grower experience.

A person can shoot for a target population by calibrating the planter and knowing the number of seeds in a pound for a given variety, which can vary tremendously among varieties. Commonly for example, there are about 4,000 to 5,000 seeds per pound. If 14 lb. of seed/acre were planted with 4,000 seeds/lb., and if 70% of these seeds successfully emerged, a stand of about 39,200 ppa might be expected. Actual seeding rates will need to vary depending upon conditions such as soil salinity or temperatures.

The best way to check populations in the field is to actually count the plants in a given area. Row lengths equal to 1/1000 of an acre can be used for the row spacings in the following table:

Table giving the row lengths to equal 1/1000 of an acre at different row spacings

Plant populations for several row widths based upon numbers of plants per foot or meter of row and spacings between plants within a given row

Full Disclaimers

Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director Cooperative Extension, College of Agriculture and Life Sciences, The University of Arizona.

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Information provided by Jeffrey C. Silvertooth,
Extension Agronomist - Cotton, College of Agriculture, The University of Arizona.
Material written February 2001.

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