When Does Annual Ryegrass Die? (Answer + Advice)

Annual ryegrass dies, most often, when temperatures are too cold or too hot. However, there are 4 other major factors that can determine if your annual ryegrass will live or die and how long it could live. Sometimes, in certain circumstances, annual ryegrass doesn’t even have to be an “annual”.

When Does Annual Ryegrass Die? (The Short Answer)

Annual ryegrass dies when the plant is no longer capable of sustaining life due to changes in temperature, nutrition, light, or water availability. Most often the determining factor for when annual ryegrass will die is temperature. If temperatures are below freezing, annual ryegrass will start taking damage until it is too damaged to live.

Table of When Annual Ryegrass is Most Likely to Die in the USA

Keep in mind that keeping an eye on the temperature (details below) is the most accurate way to determine when annual ryegrass will die where you live. However, the following table can be used to get a general idea of the window or windows when annual ryegrass may die in a certain region of the US. N = Northern, S = Southern, W = Western.

Factors that Will Affect When Your Annual Ryegrass Dies

Annual ryegrass is not nearly as resilient against change as other types of ryegrass but it still does well if treated with care and as long as best practices for annual ryegrass care are followed as closely as possible. Below are the factors that will determine how long your annual ryegrass lasts and how good it will look while it’s alive.

Temperature

At what temperature does annual ryegrass die? Annual ryegrass begins to die when temperatures reach freezing. Even sustained temperatures that hover just above freezing can cause so much damage to your annual ryegrass that it may never grow back. Further, sustained temperatures above 90F can do the same thing if water is not frequently provided to the grass.

Does annual ryegrass die in the winter? At just 50F, annual ryegrass begins to enter a period of dormancy or stasis. It will stop growing but stay green. While dormant, ryegrass should not be mown. A less frequent question is: does annual ryegrass die in the summer? At temperatures of 90F or above, annual ryegrass can go dormant and, again, while dormant your annual ryegrass should not be mown. If adequate water is not provided under these conditions, the annual ryegrass can begin taking damage and will, eventually, die.

Nutrition

Annual ryegrass is a “light feeder”. This means that it needs less nitrogen to thrive than many other grass types. As far as pros of ryegrass go, this can be a big one. The problem here is that if you fertilize it just like your primary grass type, or you accidentally combine a slow-release fertilizer with a quick-absorption fertilizer, you will end up with “burnt grass”. The good news is that, if the nitrogen build-up isn’t too bad, the burnt ends will only affect the top few inches of your grass and can be mown off within a few weeks, resulting in the typical green and healthy appearance of annual ryegrass.

On the other end of the spectrum, under-feeding your ryegrass is difficult to do unless you bag your leaves and clippings completely and there is a long-standing drought in your area. If this is the case, make sure to allow your annual ryegrass to grow up to at least 4 inches and don’t allow it to get under 3 inches. This helps your ryegrass retain nutrients and moisture for as long as possible and prevents browning that could occur as your ryegrass dries out.

Light

Annual ryegrass likes the sun, especially in cooler regions. If you want your annual ryegrass to last for more than a season, it needs at least 5 hours a day of strong, full sun. In the “winter”, even if it’s not particularly cold, ryegrass still needs at least this much sun to survive. Annual ryegrass tolerates partial or dappled sun poorly and is not a good fit for a shaded yard unless you’re using it as a fast-growing cover grass as a slower variety establishes itself.

Water

Annual ryegrass needs at least an inch of water per week, even in the winter and while it is “dormant”. Annual ryegrass is one of the few grass species that does not conserve water well while it is dormant and, as such, should not be mown during this time. Further, care should be taken when mowing annual ryegrass no matter the water situation.

Competition

Annual ryegrass does not compete well with other grass types. This is why annual ryegrass is the first choice for a mix-in or cover grass while a perennial variety (even perennial ryegrass) establishes itself. Annual ryegrass is easily crowded out by other grasses and invasive weeds.

When Something Might Not Be Quite Right …

If your annual ryegrass is browning or yellowing and things seem to be alright for the other plant life in your yard or neighborhood, you may have an outlier type of situation. Below are a few other things that can cause your annual ryegrass to die but are uncommon.

Fungal Growth

Molds and mildew can affect annual ryegrass just like any other grass type. In most cases, over-watering or too much standing water from rain is the culprit. However, “crown rust” seems to target annual ryegrass specifically after periods of cool weather (temperatures of about 50F or less.)

Crown rust will first appear as small brown spots on the ends of your blades of grass but these spots will “bloom” or expand over just a handful of days. Once bloomed, these spots will cover the entire ends of your blades of grass, resulting in the grass dying back. The good news is that infections of crown rust rarely last, as long as the weather warms up. The dead ends of the grass can then be mown off. Further, several strains of annual ryegrass available are resistant to crown rust.

Overspray or Runoff of Herbicides and Chemicals

Though unusual, you can never be too careful when using spray- or drench-type herbicides during the spring. Sudden rain can cause these chemicals to wash toward wanted plants, including your lawn. Annual ryegrass is particularly susceptible to even heavily diluted concentrations of glyphosate.