Why Is My Grass Turning Blue?

Often, when we think of the picturesque lawn, we see thick, lush, green turf. With the exception of a few grass types like blue fescue grass, turf is either green or yellow if it goes dormant in winter and summer. Cool and warm-season grass types have some variation in their colors and may change during stressful conditions, but the colors of ornamental grasses are usually predictable.

Key Points:

  • Warm and cool season grasses may turn blue as a natural defense as they adjust to climate changes.
  • Unnatural blue turf could be an indicator of serious lawn issues, such as lack of water, excess water, nutrient blockage, or weeds.
  • Purple grass is usually seen in specific ornamental grass varieties, while other non-blue grasses may turn purple due to a lack of nutrients or a low pH balance in the soil.

What happens then when the brown grass of dormancy is out of season or when the grass turns blue? Grass blades that are not from naturally blue-hued ornamental grass can become this shade, but if that occurs, it could be an indicator of serious lawn issues. Read on below to find out why your non-blue grass varieties are all of a sudden a different color and what you can do about it. 

Why Do I Have Blue Turf?

The obvious reason that turf is blue is that some common grasses, like cool-season grasses and prairie turf, have a blue tint to help with heat control and photosynthesis during climate variations. If you didn’t plant a type of grass with these attributes, then another likely scenario is that you have blue grass weeds.

While they might not be immediately identifiable, the general shade of the lawn could change as weeds lower than the lawn grass change colors and darken. 

If there are no weeds poking up through the established grass, then lack of water could be a culprit. Cultural practices like deep infrequent watering during hot summer droughts can keep grass alive during stressful seasons.

But if irrigation practices aren’t followed and the soil drys out too much, you may begin to see blue discoloration. Low-mowed grass is maybe even more susceptible to change to a blue color before turning brown, as scalping the turf crowns can lead to pre-mature grass death as well. 

Excess water can also lead to plants turning blue before dying. Poorly draining soil that is watered too frequently may develop slime and encourage fungal diseases in turf. A buildup of organic materials can turn into thatch and prevent the soil and grass roots from drying out and or getting oxygen.

Decreasing the amount of water during irrigation and dethatching can prevent disease and help grass go from blue to green again. 

Why Is My Lawn a Purple Tint?

Common grasses may also have a purple hue as purple grass exhibits these traits to capture the maximum amount of blue and red light.  Purple fountain grass is a type of grass that really lets this color show through.

Since the blue and purple spectrums bleed into each other, it can be difficult to determine if the colored grass is blue or purple, so make sure to check for the previous issues if you did not plant a purple-shaded cool-season grass. 

Purple and blue colors can also indicate serious soil problems if nutrients cannot be absorbed. A very low pH can cause a nutrient lockout, but this should be noticeable, affecting flowers and trees as well. If you suspect an issue with nutrients and no other issues like watering problems or slime are apparent, you will want to do a soil test.

You can use a probe, purchase a soil test kit, or send your soil in for testing, but regardless if you suspect that you have a nutrient or pH issue, you will want to correct it before you lose everything and waste time trying to replant on unsuitable soil. 

Is Grass Supposed to Change Colors?

Within reason, grass will change colors throughout the year. Unless you sow a mixture of warm and cool-season grasses and live in an accommodating transition zone, the possibility of grass staying green all year is slim.

Green will often turn to a common color of yellow and, in extreme dormancy, turn a brown hay-looking color.

Before going dormant, grass may turn a blue-green color and then go yellow. Mature plants that have similar weather conditions should change colors throughout the year with few deviations; if your lawn is an unexpected color, you should look into the cause immediately.  

Dyes the Turn Turf Blue

When adding liquid applications of solutions to lawns, it can be hard to know where you have sprayed when the products used do not leave a visible trace. Overspraying is dangerous for lawns and, depending on the product being laid down, also potentially harmful for humans and pets.

Lawn turf can be temporarily dyed by solutions added to herbicides, insecticides, and fertilizers to help users evenly apply liquids. Once an area of a lawn has been hit by a liquid, the blades of grass will usually take on a blue color for 24 to 48 hrs depending on water and sun exposure.

Below are 3 common lawn dye products that can be added to solutions to help with even and consistent application. 

Turf Mark Blue Spray Indicator DyeBASFLays down a blue tint and is often added to insecticide at a rate of 1/2 to 1oz of die to 1 to 3 gallons of pesticide
Liquid Harvest Lazer Blue Concentrated Spray Pattern IndicatorSancoIt can be mixed with leading brands of herbicides, pesticides, and fertilizers to prevent over spraying or missing areas of the lawn
PetraTools Blue Lawn DyePetraTools3x concentrated formula that uses less dye in solutions and fades in 24 to 48hrs via exposure to sunlight or rainfall and irrigation