Anyone who has ever set foot into a garden center, or looked at seed catalogs online, has seen the words “annual” and “perennial.” These two terms are frequently used in plant descriptions and on signs to label different aisles. But do you understand the difference? Do you wonder which is best?
Plants classified as annuals complete their entire lifecycle in a single growing season and need to be replanted every year you want them. Perennial plants may go dormant when temperatures are too high or too low, but they repeatedly grow back when growing seasons conditions are appropriate.
Without a doubt, this is a very rudimentary explanation of the physiological difference between annual versus perennial plants. Annual and perennial plants—grass seeds included—are uniquely different, and these differences make each type better suited for particular scenarios. To better decide which is best for your lawn, let’s delve into the topic a little bit deeper. Hopefully, the added information makes deciding between the two types much more effortless.
What is annual grass seed?
Annual grass plants grow for a single season, and then they don’t come back the following year no matter how perfect the growing conditions are. These plants have evolved from unpredictable or unstable habitats. Their primary goal is to develop seeds and pass on genetic information to offspring as quickly as possible.
Types of annual grass plants
Annual grass plants are broadly grouped into two categories or classifications: winter annuals and summer annuals.
Winter annuals
This type of grass typically germinates during late summer through the fall season. Also known as cold-season plants, they live through the winter when other plants are dormant and then bloom and set seed in late winter or early spring. Once they go to seed, they die.
Summer annuals
This type of annual grass germinates in late winter or early spring and produces seeds in the late spring through the early summer. They are commonly known as warm-season species and perish once temperatures drop in the fall or it frosts.
Main characteristics of annual grass seed
Since annual grass seed has a single goal in mind (to produce seed) and often grows in less than ideal environments, it has particular characteristics.
- Plants germinate and grow very quickly, taking advantage of suitable conditions when they arise, in case they are short-lived.
- Plants bloom for a more extended period to produce as many seeds and offspring as possible.
When should annual seed be used?
Since annual grass plants have a condensed lifecycle, they are best used when your turf needs a quick repair. They are a short-term solution and, in some cases, only a temporary fix to a situation that requires a more complex resolution.
Annual grasses work well when you need:
- Short-term erosion control
- Bare patches in the turf filled
- Suppression of weed species
- Interim color enhancement
They are often used when warm-season perennial grasses are dormant in the winter, and while perennial grass seed is establishing itself.
Annual grass seed varieties
There is a minimal selection of annual grass seed varieties compared to perennial grasses. Annual ryegrass and annual bluegrass are the two most common.
Annual ryegrass (Lolium multiflorum) – Annual ryegrass is used throughout the United States as a winter annual in Southern lawns and a summer annual in Northern lawns. It is tolerant of foot traffic and resistant to diseases but struggles in extreme heat and cold. Seeds germinate exceptionally quickly, sometimes in as little as three days, so this grass works well for erosion control and temporary turf until perennial grass seed establishes. Annual ryegrass is also used for winter color when warm-season grasses are dormant.
Annual bluegrass (Poa annua) – Annual bluegrass is a common weedy grass found throughout the United States. This winter annual is problematic in residential turf. It has a much lighter green color than other grasses, so it stands out and it outcompetes desired grasses for nutrients. Most homeowners try to minimize it or eradicate it from their lawns.
What is perennial grass seed?
Perennial grass plants have a life cycle that spans more than a single growing season. Unlike annuals that want to reproduce quickly because of unstable environments, perennials have evolved from stable environments with limited resources due to plant competition. Because of this, the main goal of perennials is to live as long as possible, giving themselves plenty of time to produce seed.
Seeds germinate, grass blades grow, plants bloom and produce seed, and then the grass goes dormant when temperatures drop below a specific temp in the winter. The process is repeated the following growing season when temperatures begin to warm.
Dormancy is a natural way the plant protects itself from extreme conditions. Instead of dying off, metabolism and respiration slow—much like animals hibernate for the winter—to prevent permanent cellular and tissue damage. The plant resumes cellular processes and active growth when the environment improves again.
Types of perennial grasses
Perennial grass plants are classified as either warm-season or cool-season varieties.
Warm-season perennial grasses
- Warm-season grasses are grown in Southern areas, where summer temperatures are hot and winters are mild, often without snow.
- They green up at the end of spring and go dormant in late September to October.
- They produce most of their biomass when it’s hot from July to September when temperatures average 85°F to 95°F.
Cool-season perennial grasses
- Cool-season grasses are grown in the North, where summers are milder, but winters can be harsh with a decent amount of snow.
- These types are greener for a longer time than warm-season varieties. They green up early to mid-spring and keep their color until October or November.
- Most biomass is produced early or late in the year when temperatures are between 65 and 75°F.
Main characteristics of perennial grass seed
Intending to live as long as possible in areas with limited resources, perennial grass seeds have different characteristics than annual seeds.
- Plants germinate and grow slowly and steadily, carefully utilizing their resources for long-term sustainability.
- Plants develop deeper, more extensive root systems because they have a longer time to grow and are trying to access more nutrients and water in the soil.
- Plants have a shorter bloom time each year as they need to reserve energy for preparing for winter dormancy.
When should perennial seed be used?
With a much longer lifecycle than annual grass seed, perennial seed should be used when you’re looking for long-term, permanent solutions. They are the standard for seeding and establishing new lawns or reseeding lawns that are beginning to decline due to age or disease.
Perennial Grass Seed Varieties
When it comes to choosing a perennial grass seed for your lawn needs, there are many options. Most turfgrass varieties are classified as perennial plants and are readily available for purchase.
- Perennial ryegrass (Lolium perenne)
- Tall fescue (Festuca arundinacea)
- Bermudagrass (Cynodon dactylon)
- Bahiagrass (Paspalum notatum)
- Kentucky bluegrass (Poa pratensis)
- St. Augustine grass* (Stenotaphrum secundatum)
- Creeping bentgrass (Agrostis palustris)
- Buffalo grass (Buchloe dactyloides)
- Zoysiagrass (Zoysia japonica)
*Note: St. Augustine grass is not available to plant by seed. It can only be established in a lawn by sod plug, or sprig.
Difference between annual and perennial grass seed
The contrast between single-season annuals and multi-season perennials also results in significant secondary differences.
- Annuals grow quickly; perennials grow slower.
- Annuals have short, compact roots systems; perennials have deeper, more extensive roots.
Sometimes, these characteristics work in the plant’s favor, and other times, they disadvantage the plant.
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Related FAQ’s
Q. When should I plant new grass seed in spring?
Warm-season grasses should be planted in early spring when the air and soil temperatures begin to warm. Depending on the climate, this can be from February to April.
Q. Can you store grass seed over the winter?
Yes, you can store grass seed over the winter. Keep seed somewhere it is cool, dark, and dry. The best spot has a temperature above 40°F but no higher than 60-70°F with relative humidity below 60%.
Q. Can you use year-old grass seed?
Yes, you can use year-old grass seed if it was properly stored. When kept in a dark, dry, cool location, grass seed stays viable for 18 months from the testing date listed on the bag.
Q. How long will grass seed last in the ground?
If it is cool and dry, grass seed stays dormant and can last in the ground for a few months. Too much moisture encourages rot, and once temperatures reach a certain point, germination begins.
Q. Will grass seed grow if I just throw it down?
Grass seed will grow if you don’t do any prep work and just throw it down, but the germination rate will be lower. You’ll see the most success if the soil bed is prepared correctly and the grass seed is well cared for after sowing.
Q. Can you just sprinkle grass seed on the lawn?
You can just sprinkle grass seed on the lawn, but germination will be much lower than if the area is correctly prepared before overseeding.
Q. Can I overseed in February?
In February, you can overseed warm-season grasses if you live in a warm climate. The soil temperatures need to be above 50-60°F for germination.
Conclusion – Should I use Annual or Perennial Grass Seeds?
Truthfully, the answer to this question greatly depends on you and the lawn situation you are addressing. If you want a quick fix or short-term solution, then annual grass seeds are the better answer of the two. However, if you need steady growth and a long-term solution, perennial grass seeds should be considered.
The bottom line is annual grass seeds are important in certain situations, but they hold much less value than their perennial counterparts since they flourish and fade quickly in a single growing season. Perennial grass seeds provide more intrinsic value to your lawn, from season to season for many years.