Identifying growth stages (GS) in crops is crucial in order to apply fertiliser, herbicides, growth regulators and fungicides at the correct timings.

Deciphering between GS30, GS31 and GS32 can be tricky. To help, AgriLand has put together a guide to identify these growth stages. You will need a sharp knife and a ruler or measuring tape.


GS30 signals the end of the vegetative stage of the plant and the beginning of the reproductive stage. In other words, the plant is focusing on grain production from this point on.

Image source: Teagasc

At GS30, the plant will look like the picture above. The tillers are formed and the plant is moving into stem elongation. To be sure that the plant is at GS30, it must be dissected. Pull a plant and take the main tiller. Using a sharp knife, cut the stem down the middle.

At GS30, there will be 1cm between the bottom of the plant (bottom of the leaves) and the shoot apex (the top of the ear). There may be more than 1cm between the bottom of the plant and the shoot apex; but the first internode will be less than 1cm. This is shown in the picture below.

Image source: Teagasc


GS31 (first node detectable) occurs when the shoot apex is 2-3cm above ground level. An internode may be 1cm or more. However, the internode above it will be less than 2cm.

Image source: Teagasc


GS32 (second node detectable) occurs when the node below the second node (and subsequent nodes) is 2cm or more.

Image source: Teagasc