Overseeding Bermuda With Zoysia

If you have a bermuda grass lawn, you might be thinking about overseeding bermuda with zoysia for a lush, green lawn. This is a common strategy for homeowners who want a denser turf with better seasonal color. It can work, but it requires a clear understanding of both grass types and a very specific approach.

This guide will walk you through the entire process. We’ll cover the pros and cons, the best timing, and the exact steps to take. Our goal is to give you the knowledge to make an informed decision and, if you proceed, to do it correctly.

This heading might seem straightforward, but it describes a complex lawn renovation technique. It’s not like overseeding a cool-season lawn with ryegrass in the fall. Instead, it’s about introducing a different warm-season grass to permanently alter your lawn’s composition.

Zoysia grass is known for its thick, carpet-like growth and good shade tolerance compared to bermuda. Bermuda grass is aggressive, drought-tolerant, and recovers quickly from damage. The idea is to get zoysia to establish within the bermuda, creating a blended lawn that may stay greener longer in the fall and handle varying light conditions better.

Why Consider This Method?

There are a few reasons this idea appeals to lawn owners.

You want a thicker, more weed-resistant turf without starting from scratch.
Your lawn has areas of partial shade where bermuda struggles but zoysia might survive.
You prefer the finer texture and darker green color of certain zoysia varieties.
You hope for a lawn that goes dormant later in the fall or greens up earlier in the spring.

The Major Challenges and Realities

Before you buy a single seed or plug, you need to understand the significant hurdles.

Different Growth Habits: Bermuda spreads rapidly with above-ground stolons and below-ground rhizomes. Zoysia spreads slowly, primarily with stolons. The bermuda can easily outcompete the young zoysia if not managed aggressively.
Establishment Time: Zoysia is notoriously slow to establish, whether from seed, sod, or plugs. It can take two to three growing seasons to fully fill in.
Mowing Height Conflict: Bermuda thrives when mowed very low (1-2 inches). Most zoysia varieties prefer a higher cut (1.5-2.5 inches). You’ll have to compromise on a height, which may not be ideal for either grass.
Potential for a Patchy Look: During the long establishment phase, your lawn may look uneven as the two grasses grow at different rates and textures.

Choosing the Right Zoysia Variety

Not all zoysia grasses are created equal. For overseeding into an existing bermuda lawn, you need a variety that can hold its own.

Zenith or Compadre Zoysia: These are seeded varieties. This is the most common method for “overseeding.” They are more affordable but can be even slower to establish.
Zoysia Japonica Varieties (like El Toro or Empire): These are more aggressive spreaders among zoysias and may compete better with bermuda. They are typically installed as sod or plugs.
Zoysia Matrella Varieties (like Zeon or Geo): These have a very fine texture but are the slowest to spread. They are not recommended for this purpose due to high cost and slow growth.

Your local garden center or extension service can advise on the best variety for your specific climate zone. Its important to get this right from the start.

The Critical Step: Preparation is Everything

Success depends almost entirely on what you do before planting. You must weaken the existing bermuda grass to give the zoysia a fighting chance.

Step 1: Timing is Key

The best time to do this is in the late spring to early summer, when soil temperatures are consistently above 70°F. Both grasses need warm soil to grow. This gives the zoysia maximum time to establish before any fall dormancy.

Step 2: Scalp and Dethatch

Begin by mowing your bermuda lawn as low as your mower safely allows. This removes excess leaf material and exposes the soil. Follow this with a thorough dethatching to remove the layer of organic matter at the soil surface. This barrier prevents zoysia seeds or plugs from making good soil contact.

Step 3: Aerate the Lawn

Go over the entire lawn with a core aerator. This creates channels in the soil for water, nutrients, and the new zoysia roots. It also relieves compaction, which helps both grasses.

Step 4: The “Chemical” Option for Aggressive Control

This is a controversial but often necessary step. To seriously slow the bermuda down, some professionals apply a grass-specific herbicide like Fusilade II or Ornamec about 2 weeks before planting the zoysia. These products contain fluazifop, which suppresses bermuda growth without killing it outright.

Warning: This requires careful calibration and adherence to label instructions. Misapplication can damage or kill both grasses. Consider consulting a pro if your unsure about this step.

The Planting Process

Now, you’re ready to introduce the zoysia. The method you choose depends on your budget and patience.

Using Zoysia Seed

Apply the seed at the rate recommended on the bag, usually 1-2 pounds per 1000 square feet.
Use a broadcast spreader for even coverage. Go over the lawn twice in perpendicular directions.
Lightly rake the area to help cover the seed with a thin layer of soil. Do not bury it deeply.
Apply a starter fertilizer high in phosphorus to promote root growth.

Using Zoysia Plugs

After prepping the lawn, mark a grid pattern, spacing plugs 6-12 inches apart. Closer spacing fills in faster but costs more.
Use a specialized plugging tool or a sturdy trowel to dig holes for each plug.
Place a plug in each hole and firm the soil around it to ensure good contact.
Water thoroughly immediately after planting.

Post-Planting Care: The Make-or-Break Phase

This is where most projects fail. Consistent care for the first year is non-negotiable.

Watering Schedule

For seed, you must keep the top inch of soil constantly moist (not soggy) for 14-21 days. This may require light watering 2-3 times a day initially. For plugs, water deeply daily for the first two weeks, then gradually reduce frequency to encourage deep rooting.

Mowing Strategy

Do not mow until the new zoysia is well-established. For seed, wait until it reaches about 3 inches tall. For plugs, wait until they begin to spread and send out runners. Then, set your mower to a compromise height of around 1.5-2 inches. This is low enough for bermuda but high enough for zoysia.

Fertilizing

Apply a balanced fertilizer (like a 16-4-8) 6 weeks after planting. Continue to fertilize every 6-8 weeks during the active growing season, following soil test recommendations. Avoid excessive nitrogen, which will primarily benefit the aggressive bermuda.

Weed Control

You must be extemely careful with herbicides during establishment. Most weed controls cannot be used on zoysia seed until after it has been mowed 2-3 times. For plugs, wait at least 30 days. Hand-pulling weeds is the safest method initially.

Long-Term Management of a Mixed Lawn

If successful, you’ll have a blended lawn. It will require ongoing management tailored to both grasses.

Continue mowing at the compromise height.
Water deeply but infrequently to encourage deep roots for both types.
Monitor for one grass overtaking the other. You may need to periodically overseed with zoysia in thin areas or use a growth regulator to slow the bermuda’s vertical growth.
Expect that the bermuda will likely still be the dominant grass in full sun areas, while zoysia may prevail in shadier spots.

Is There a Better Alternative?

Given the challenges, you should consider other options.

Complete Renovation: Killing the entire bermuda lawn with glyphosate and installing 100% zoysia sod. This is more expensive but gives a uniform result much faster.
Embrace Bermuda: Optimize your bermuda lawn with proper low mowing, fertilization, and watering. A healthy bermuda lawn is very beautiful and durable on its own.
Overseed with Ryegrass: For just winter color, the traditional method is overseeding bermuda with perennial ryegrass in the fall. This provides green color in the winter while the bermuda is dormant, then dies back as the bermuda greens up.

FAQ Section

Can you overseed bermuda grass with zoysia grass?

Yes, it is technically possible, but it is not a simple overseeding like with ryegrass. It’s a long-term lawn modification project with a high risk of the bermuda outcompeting the zoysia. Success requires intensive preparation and follow-up care.

Will zoysia take over bermuda grass?

In most cases, no. Bermuda grass is more aggressive and faster-spreading. In ideal conditions for zoysia (some shade, higher mow height), it may coexist or win in small areas. But in full sun, bermuda will usually remain dominant unless you actively and repeatedly suppress it.

What is the best zoysia to mix with bermuda?

More aggressive zoysia varieties like ‘El Toro’ or ‘Empire’ (japonica types) have a better chance of competing. Seeded varieties like ‘Zenith’ are cost-effective for broad coverage but are very slow. The “best” choice depends on your budget, installation method, and specific lawn conditions.

How long does it take for zoysia plugs to spread in bermuda?

It can take 2-3 full growing seasons for zoysia plugs to spread and form a solid stand within a bermuda lawn. Growth is slow in the first year as the plant focuses on root development. You must be patient and protect the young plugs from being overwhelmed.

Final Thoughts

Overseeding bermuda with zoysia for a lush, green lawn is a ambitious project for a dedicated lawn enthusiast. It is not a quick fix. It demands significant preparation, precise timing, and a commitment to careful management for seveal seasons.

You must weigh the desire for zoysia’s qualities against the effort required and the high chance of a mixed result. For many, improving their existing bermuda lawn or saving for a full zoysia sod renovation is a more practical and predictable path. However, if you enjoy a hands-on lawn care challenge and understand the realistic outcomes, this method provides a way to gradually change your turf’s character.