Researchers at Lincoln University in New Zealand have identified the cause of this change in leaf colour as an increase in the concentration of the pigment “anthocyanin”.

Unlike the well-known green pigment chlorophyll which is responsible for the usual green colouring we see in plant leaves, anthocyanin is responsible for the red or purple colours we see in many of our deciduous plants in autumn and in some of our clover leaves in winter.

The long run of frosts and cold nights we have experienced this winter may have resulted in some clover leaves developing a red-purple colour as the season progresses. Not all leaves are affected, but many clover varieties display such a reaction to the cold.  

The accumulation of this red pigmentation in clover leaves at this time of year is simply the plants natural response to stress caused by the cold and is considered to be a defence mechanism. The researchers have found that these red clover leaves are less palatable to livestock but if grazed there are no negative effects.

Once we emerge out of winter and our average minimum temperatures increase above 6 degrees C, this red pigment should dissipate and the green pigment chlorophyll should once again dominate our clover leaves. Thankfully, there also seems to be no long term impact on the plants with researchers reporting no negative effects on clover herbage mass production following such an event.

So, like for us humans when leaving a cold to run its course can be a good option as long as nothing else is amiss; leaving our red coloured clover to endure our cold winter is fine.

However, if the clover leaf reddening does not dissipate during spring or it occurs during the warmer months of the year it may be a symptom of something more serious. Nutrient deficiency, herbicide toxicity, drought stress and clover virus can all be responsible for the reddening of clover leaves so it pays to keep a close eye on your pasture year-round.

For further information contact your local agronomist or Local Land Services.