Does Grass Grow at Night?

In the summer, when the grass needs to be mowed most frequently, it can seem like every morning when you step out the door your lawn has grown an inch- even if you just mowed it yesterday. Does that mean that the grass grows faster at night? Does grass even grow at night? These are both common questions and the good thing is there are simple answers and explanations for both of these.

Does Grass Grow at Night?

Yes, grass grows at night. During the day, the grass absorbs plenty of sunlight and converts it into energy that it can store to use overnight or during a very dark, cloudy day. However, though grass does grow at night, its growth rate will begin to slow and taper off to dormancy if the “night” or period of darkness continues for longer than about 6 hours.

Does Grass Grow More at Night?

No, grass does not grow more at night. Night or darkness itself does not cause grass to grow more than it would during the day. However, increased moisture and cooler temperatures can improve the growth rate of grass and many other plants in hot, dry climates or at the peak of summer.

For example, say it’s summer in northern Illinois and temperatures have hit 95F during the day and cool off to 75F at night. With increased humidity and lower temperatures, the growth rate of fescue or perennial ryegrass can as much as double for 4 to 6 hours as temperature cool off at night. There can also be a sudden growth spurt as the sun rises in the morning and the grass rushes to replenish its stored nutrients.

What Does Grass Need to Grow?

Several factors influence the growth rate of grass and decide whether it grows better at night, during the day, or has an even growth rate no matter what time it is.

• Heat – Temperatures have a strong correlation to how quickly grass will grow. Almost no grass will grow as temperatures dip close to or below freezing, for example. There is, however, a temperature sweet spot for all grass types and most grasses experience a much faster or even doubled growth rate within this range compared to +/- 20F around it.
• Light – All plants need some amount of light to survive. Grass can store up the nutrients and energy it gains from sunlight, but only for a short time.
• Nutrients – As with light, the nutrients grass requires are not all obtainable at night. As long as the nutrient stores within the plant are at acceptable levels, it will continue to grow.
• Water – Grass needs water to grow. It’s used to transport nutrients and facilitate the process of growth. At high temperatures, less water will be available for these processes. The lower temperatures at night can help free up more water for growth.

How Night Affects Grass Growth

Night affects the growth rate of grass by limiting the access grass has to sunlight and lowering the overall temperature. This can have a multitude of effects. For example, in the winter, this can keep the grass in a period of dormancy or cause damage if temperatures are suddenly or unusually low. In summer, however, lower temperatures at night and long periods of sunlight during the day can boost growth at night.

In any case, if the grass has had recent sunlight exposure and temperatures are within the growing range, grass should grow as night. Most often, this will be the same growth rate as during the day unless temperatures were unfavorable during the day.