Rye, Rye Grass- what’s the difference?

This is a question that many Extension Agents and commercial pasture managers get asked each fall.  When you get into a conversation with horse owners about this topic, you will always be able to group people into one of three categories. Those that fully understand the difference, those that have no clue there is a difference, and those that understand the difference but interchange the proper terms for the two forages without thinking about it. Regardless of which category you find yourself in, let’s discuss the two different grasses and their pros and cons.

Cereal Rye and ryegrass are two different species (though closely related) of grass . They do have much in common. They are both annuals, meaning that they have to be replanted every year (preferably in the fall)  and will germinate, grow and die in a few months. The plant does in fact completely die, not just goes dormant such as bermudagrass in the winter. This is what distinguishes an annual from a perennial.  They are both considered cool season annuals that ideally need to be planted in the early fall. They both will provide grazing in the spring (and possibly earlier in the year depending on how mild a winter we have).  The two types of grass are almost identical when they first emerge out of the ground, and will not really be distinguishable until they start to grow and get bigger. This is also why you have the confusion that sometimes arises when people use the two terms interchangeably.  For all their similarities however, they are some big differences that separates the two species.

Cereal Rye, which depending on where you reside in the world tends to be referred to as just rye,  is actually a plant that is grown for grain as much as it is a forage. It is planted in the fall and can grow in colder weather than rye grass. It is not uncommon for cereal rye to be growing at full speed by the first of February in a mild winter.  Rye will complete its growth cycle by forming a mature seed head by the end of April/first of May. This is when you can easily tell if you have cereal rye in your paddocks. If left to grow and mature, cereal rye will get very tall and “stemmy” and the palatability (as well as the nutrient content) of the forage will decrease to the point that grazing will stop completely.  Cereal Rye is best managed by grazing the forage heavily before it gets over 5-6 inches tall. If your horse are not able to keep up with the growth of the rye than mowing it is certainly an option. Mowing will almost be a necessity regardless of your management skill by the first of May to remove any Rye residue, which will rob your emerging bermudagrass of critical sunlight in the late spring. This is also a point that not everybody understands about Cereal Rye in bermuda. Regardless of how good a manager you are, rye will slow your bermuda growth in the spring and will cost you 2-4 weeks or growth out of your bermuda in the early growing season.  Given the additional grazing time you get off of the rye however, most people view this as the lesser of two evils.

Rye Grass is similar in a lot of aspects, but it does have some key differences. It too is planted in the fall, and is almost identical to cereal rye when very small. The differences between rye grass and cereal rye does not become apparent until the plant starts to get some size on it. Rye grass has a much thicker leaf and does not put its energy into forming a seedhead. It grows much lower to the ground and appears to be “bunchier”.  As the feed value (protein and energy) of any plant is in the leaf, it is for this reason that ryegrass is generally considered a much better forage for animals.  The plant will keep good palatability much longer into its growth cycle than cereal rye will.  If Rye grass is such a better forage than why would people ever put cereal rye into their bermuda paddocks over rye grass? The reason is that ryegrass grows much later into the spring (and even into the early summer). The problems associated with the spring competition that was discussed in the cereal rye section above are multiplied by a factor of 5 with ryegrass. Ryegrass grows the greatest in April and May, which is at the exact time bermuda is struggling to break dormancy.  With Cereal Rye being at the end of its natural life cycle, you can mow it or graze it heavily and reduce this competition to a manageable level during this critical time of the year. With Ryegrass, this competition reduction is not possible. The rapidly growing ryegrass will cause severe damage to your bermuda stand  during this time.  This is why for all of its short comings, cereal rye is vastly preferred by agronomist over ryegrass if used in an existing stand of bermudagrass.

There are also blends of rye and ryegrass available on the market. The ratio of cereal rye to rye grass seeds will vary depending on the brand name.

Written by Randy Wood